Term
| bottom of cloud is this humidity |
|
Definition
|
|
Term
| air does this as it rises |
|
Definition
|
|
Term
| evaporation is a ______ process and condensation is a ______ process |
|
Definition
|
|
Term
| air holds (more or less) water as it cools down |
|
Definition
|
|
Term
| how to calculate relative humidity |
|
Definition
| (actual humidity)/(total possible humidity) |
|
|
Term
| master index of how much water vapor atmosphere can hold |
|
Definition
|
|
Term
| warm and cold air masses interact this way to cause storms |
|
Definition
| warm air mass settles above the cold air mass and causes storms |
|
|
Term
| frontal storms occur this time of year |
|
Definition
|
|
Term
| convective storms occur this time of year |
|
Definition
|
|
Term
| mesoscale connective complexes (MCC's) |
|
Definition
|
|
Term
|
Definition
| storm that would occur once every 10 year |
|
|
Term
| the best indicator of weather patterns over the years |
|
Definition
|
|
Term
| mulching ______ evapotranspiration |
|
Definition
|
|
Term
| pan evaporation is a function of... |
|
Definition
|
|
Term
| Do fish like hot water near shore? |
|
Definition
|
|
Term
| trees on the shoreline reduce ______ and cool down the shoreline |
|
Definition
|
|
Term
|
Definition
|
|
Term
| These plants tend to have a low leaf area index. |
|
Definition
|
|
Term
| stem flow down a tree can help do this |
|
Definition
|
|
Term
| drought triggers this in plants |
|
Definition
| survival mode; going into fruit |
|
|
Term
| The relationship between precipitation and evapotranspiration control... |
|
Definition
-what types of plants can grow
-how soils form and behave
-the structure and variability of fish habitat
-how many people can live there |
|
|
Term
| why Seattle seems wetter on less rainfall than north Georgia |
|
Definition
| warmer, sunnier climate in Georgia drives more evapotranspiration |
|
|
Term
| If rainfall is constant, increasing ______ means decreasing ______. |
|
Definition
evapotranspiration
streamflow |
|
|
Term
| the person who proved the law of conservation of mass |
|
Definition
|
|
Term
| the accounting principle behind most water resource questions |
|
Definition
| what goes in must equal what comes out |
|
|
Term
|
Definition
| the input in the hydrologic cycle |
|
|
Term
| factors of precipitation that can have effect |
|
Definition
| annual amount, seasonal distribution, and intensity |
|
|
Term
| precipitation occurs when... |
|
Definition
| a mass of air is cooled to the dewpoint |
|
|
Term
|
Definition
| the temp at which the relative humidity is 100% |
|
|
Term
| Why is the temp at higher elevations colder than at lower elevations? |
|
Definition
because the air pressure at higher elevations is lower
pertains to ideal gas law (PV=nRT) |
|
|
Term
| The atmosphere keeps moving primarily because of these reasons: |
|
Definition
1: hot air rises
2: cold air falls
3: our sun does not heat our planet evenly |
|
|
Term
|
Definition
| zones where air moves in circles in the atmosphere |
|
|
Term
| What sets up circulation cells? |
|
Definition
| the rising and falling of air at the extremes of the Earth |
|
|
Term
| This partly explains why most places have a prevailing wind direction. |
|
Definition
|
|
Term
| most of northeast Georgia's weather comes from... |
|
Definition
|
|
Term
| Do global circulation belts expand and contract? |
|
Definition
|
|
Term
| regional winds are affected by... |
|
Definition
land masses, ocean circulation, vegetative conditions, etc.
this is why atmospheric circulation is more complicated than circulation cells |
|
|
Term
| most atmospheric circulation is driven by... |
|
Definition
| differential solar heating |
|
|
Term
|
Definition
| the rate of temp decline w/ altitude |
|
|
Term
| average lapse rate also called... |
|
Definition
|
|
Term
| dry air lapse rate holds for... |
|
Definition
|
|
Term
| wet air lapse rate holds for... |
|
Definition
|
|
Term
| the average lapse rate is more typically for... |
|
Definition
|
|
Term
| why wet air does not cool as quickly as dry air |
|
Definition
| because water vapor gives off heat as it condenses and cools off as it evaporates |
|
|
Term
| saturation vapor pressure (es) |
|
Definition
| the maximum amount of water that the air can hold |
|
|
Term
|
Definition
|
|
Term
| actual vapor pressure (ea) |
|
Definition
| the actual amount of water in the air in millibars |
|
|
Term
| Why is the wet lapse rate less than the dry lapse rate? |
|
Definition
| As wet air rises, the atmosphere becomes saturated and the relative humidity reaches 100%. To cool further requires that the atmosphere releases some of its moisture as precipitation (rain if the air is above freezing, snow or ice if it is below freezing). The condensation of water releases heat (just as the evaporation of heat cools). This release of heat warms the air slightly, so the air does not cool as fast as the dry air would. |
|
|
Term
| Fronts form here and generate this. |
|
Definition
at the boundaries of air masses with contrasting temperatures
most of the precipitation in the mid latitudes from 30° to 60° North and South |
|
|
Term
| In the northern hemisphere, fronts typically occur when... |
|
Definition
| a polar air mass meets a tropical air mass. |
|
|
Term
|
Definition
| storms that happen as a result of a polar air mass and a tropical air mass colliding |
|
|
Term
| For a frontal storm to produce rain, one of the air masses must have this. |
|
Definition
|
|
Term
|
Definition
-maretime tropical
-maretime polar
-continental tropical
-continental polar |
|
|
Term
| maretime tropical air mass |
|
Definition
|
|
Term
|
Definition
|
|
Term
| continental tropical air mass |
|
Definition
|
|
Term
| continental polar air mass |
|
Definition
|
|
Term
|
Definition
| changes in temp with distance |
|
|
Term
|
Definition
| 100-200km band between air masses |
|
|
Term
| As the air masses slide along one another, the ______ often creates ______. |
|
Definition
|
|
Term
|
Definition
| a quick change in wind direction |
|
|
Term
|
Definition
| swirling air that rotates counterclockwise in the northern hemisphere |
|
|
Term
| What happens to the colliding air along the front? |
|
Definition
| warm air settles on top of cold air and then the warm air cools below the dewpoint and causes precipitation |
|
|
Term
| Warm fronts generally cause these type of storms. |
|
Definition
|
|
Term
| Cold fronts generally cause these types of storms. |
|
Definition
|
|
Term
|
Definition
also called thunderstorms
short lived (1-2 hour) storms that typically produce high intensity rainfall |
|
|
Term
| Convection storms occur as the result of... |
|
Definition
either...
1: rising cells of excessively heated moist air
2: mountain uplift causing air mass instability
3: air mass discontinuity along a squall line |
|
|
Term
| Thunderstorms in Georgia typically occur during... |
|
Definition
| periods of high humidity during the summer when the state is covered by maretime tropical air mass |
|
|
Term
| Convection storms are triggered by... |
|
Definition
| unequal heating of air near the ground surface |
|
|
Term
| What causes a convection storm to rise more? |
|
Definition
| As the heated air rises, water vapor condenses releasing the latent heat of vaporization, which further heats the air mass and causes it to rise more. Continues as long as the air mass is warmer than the surrounding air. |
|
|
Term
| mesoscale convective complexes (MCC's) |
|
Definition
circular or semi-circular groups w/ a strong squall line along a clear front of thunderstorms
Thunderstorms in Georgia are often associated with mesoscale convection complexes.
The formation and structure of these is still poorly understood. |
|
|
Term
|
Definition
| These storms are caused when wind moves moist air over a mountainous region, thereby increasing the altitude and reducing the temp of the air mass. |
|
|
Term
| What part of Georgia gets the most rain? |
|
Definition
|
|
Term
|
Definition
| area with little precipitation on the downwind side of a mountain range |
|
|
Term
| tropical cyclones aka hurricanes aka typhoons |
|
Definition
| storms formed over oceans with warm surfaces temperatures (large areas in excess of 27°C) |
|
|
Term
|
Definition
| low pressure cell that can sometimes create a cyclonic vortex |
|
|
Term
| Cyclonic vortex does this. |
|
Definition
| creates convective cells near the middle, causing a self-reinforcing cycle of heat and mass transfer |
|
|
Term
| lake effect precipitation |
|
Definition
| precipitation that happens as a result of a lake in the local area |
|
|
Term
|
Definition
|
|
Term
| In summer, cooler lake water does this. (regarding precipitation) |
|
Definition
| stabilizes air masses, thus reducing leeward precipitation |
|
|
Term
|
Definition
time related variability in precipitation
causes droughts and floods
occurs at many temporal scales, such as year to year and month to month |
|
|
Term
|
Definition
| plot of the depth of rainfall vs. a specified duration |
|
|
Term
|
Definition
| the instantaneous rate of rainfall expressed in depth/time (mm/hour, inches/hour, etc.) |
|
|
Term
| low intensity of rainfall |
|
Definition
|
|
Term
| medium intensity of rainfall |
|
Definition
|
|
Term
|
Definition
|
|
Term
| extreme intensity rainfall |
|
Definition
|
|
Term
| intensity of rainfall vs. length of rainfall |
|
Definition
| most likely to be inverse |
|
|
Term
| One can't determine the probability of a precipitation volume or an intensity without... |
|
Definition
| specifying a time interval for the storm |
|
|
Term
| storm and flood probabilities are often described by... |
|
Definition
|
|
Term
|
Definition
| the average amount of time between occurrences of a particular storm |
|
|
Term
| an x year storm has a return interval of... |
|
Definition
|
|
Term
| Tr regarding return period |
|
Definition
| average return interval in years |
|
|
Term
| P regarding return period |
|
Definition
| annual exceedence probability |
|
|
Term
| annual exceedence probability |
|
Definition
| the probability of a particular storm happening in any given year |
|
|
Term
|
Definition
| the frequency of the storm |
|
|
Term
|
Definition
used to determine the duration of the storm
you use a small time of concentration for small watersheds and a large time of concentration for large watersheds |
|
|
Term
| geographic variability (aka spatial variability) |
|
Definition
|
|
Term
| Climate varies accross the Earth because of... |
|
Definition
| differences in the factors that cause precipitation, such as proximity to oceans, distribution of mountains, location with respect to atmospheric circulation cells, and latitude |
|
|
Term
| major categories of climate by rainfall per year |
|
Definition
arid, desert: <10"
semi-arid, mediterranean: 10-20
humid: 20-60
rainforest: >60 |
|
|
Term
| rain pattern in the eastern US |
|
Definition
| relatively uniform throughout the year |
|
|
Term
|
Definition
summer rainy period
parts of the desert southwest have this |
|
|
Term
| Precipitation and climate determine these things regarding plants. |
|
Definition
| plant growth potential, plant water demand, and seasonality of evapotranspitation |
|
|
Term
| Georgia's tearly rainfall average |
|
Definition
| 50"/year on average, but can vary + or - 20% |
|
|
Term
| Winter rains are usually this type of storm |
|
Definition
frontal
long w/ low to moderate intensities |
|
|
Term
| summer rains are usually this type of storm |
|
Definition
convective
short w/ high intensity and large aerial variation |
|
|
Term
| Why might it rain in Watkinsville and not in Athens? |
|
Definition
| large aerial variation during summer cunvective storms |
|
|
Term
|
Definition
seasonal variation
pretty low here in Georgia |
|
|
Term
|
Definition
-evaporation and transpiration
-returns water from ground, water, rivers, lakes, oceans, and plants back to the atmosphere
-expresses as a rate (depth of water over time) that is either evaporated from surface waters and soils or transpired from plants |
|
|
Term
| Evaporation occurs when... |
|
Definition
| molecules of liquid water attain enough kinetic energy to overcome surface tension and escape from the water surface |
|
|
Term
| Most of the energy that drives evapotranspiration comes from... |
|
Definition
| solar radiation and sensible heat transfer from the atmosphere |
|
|
Term
|
Definition
|
|
Term
| latent heat of vaporization |
|
Definition
| the energy it takes to evaporate 1 gram of something |
|
|
Term
| latent heat of vaporization for water |
|
Definition
|
|
Term
| evaporation rate depends on... |
|
Definition
|
|
Term
| Why does water evaporate slower at higher humidity? |
|
Definition
| As the humidity of the air increases, so does the partial pressure of water vapor in the air, and it becomes more difficult for water to evaporate. |
|
|
Term
| evapotranspiration vs. vapor pressure |
|
Definition
| evapotranspiration increases with increasing vapor pressure deficit |
|
|
Term
|
Definition
|
|
Term
| Why is the wet lapse rate less than the dry lapse rate? |
|
Definition
| As wet air rises, the atmosphere becomes saturated and the relative humidity reaches 100%. To cool further requires that the atmosphere releases some of its moisture as precipitation (rain if the air is above freezing, snow or ice if it is below freezing). The condensation of water releases heat (just as the evaporation of heat cools). This release of heat warms the air slightly, so the air does not cool as fast as the dry air would. |
|
|
Term
| Fronts form here and generate this. |
|
Definition
at the boundaries of air masses with contrasting temperatures
most of the precipitation in the mid latitudes from 30° to 60° North and South |
|
|
Term
| In the northern hemisphere, fronts typically occur when... |
|
Definition
| a polar air mass meets a tropical air mass. |
|
|
Term
|
Definition
| storms that happen as a result of a polar air mass and a tropical air mass colliding |
|
|
Term
| For a frontal storm to produce rain, one of the air masses must have this. |
|
Definition
|
|
Term
|
Definition
-maretime tropical
-maretime polar
-continental tropical
-continental polar |
|
|
Term
| maretime tropical air mass |
|
Definition
|
|
Term
|
Definition
|
|
Term
| continental tropical air mass |
|
Definition
|
|
Term
| continental polar air mass |
|
Definition
|
|
Term
|
Definition
| changes in temp with distance |
|
|
Term
|
Definition
| 100-200km band between air masses |
|
|
Term
| As the air masses slide along one another, the ______ often creates ______. |
|
Definition
|
|
Term
|
Definition
| a quick change in wind direction |
|
|
Term
|
Definition
| swirling air that rotates counterclockwise in the northern hemisphere |
|
|
Term
| What happens to the colliding air along the front? |
|
Definition
| warm air settles on top of cold air and then the warm air cools below the dewpoint and causes precipitation |
|
|
Term
| Warm fronts generally cause these type of storms. |
|
Definition
|
|
Term
| Cold fronts generally cause these types of storms. |
|
Definition
|
|
Term
|
Definition
also called thunderstorms
short lived (1-2 hour) storms that typically produce high intensity rainfall |
|
|
Term
| Convection storms occur as the result of... |
|
Definition
either...
1: rising cells of excessively heated moist air
2: mountain uplift causing air mass instability
3: air mass discontinuity along a squall line |
|
|
Term
| Thunderstorms in Georgia typically occur during... |
|
Definition
| periods of high humidity during the summer when the state is covered by maretime tropical air mass |
|
|
Term
| Convection storms are triggered by... |
|
Definition
| unequal heating of air near the ground surface |
|
|
Term
| What causes a convection storm to rise more? |
|
Definition
| As the heated air rises, water vapor condenses releasing the latent heat of vaporization, which further heats the air mass and causes it to rise more. Continues as long as the air mass is warmer than the surrounding air. |
|
|
Term
| mesoscale convective complexes (MCC's) |
|
Definition
circular or semi-circular groups w/ a strong squall line along a clear front of thunderstorms
Thunderstorms in Georgia are often associated with mesoscale convection complexes.
The formation and structure of these is still poorly understood. |
|
|
Term
|
Definition
| These storms are caused when wind moves moist air over a mountainous region, thereby increasing the altitude and reducing the temp of the air mass. |
|
|
Term
| What part of Georgia gets the most rain? |
|
Definition
|
|
Term
|
Definition
| area with little precipitation on the downwind side of a mountain range |
|
|
Term
| tropical cyclones aka hurricanes aka typhoons |
|
Definition
| storms formed over oceans with warm surfaces temperatures (large areas in excess of 27°C) |
|
|
Term
|
Definition
| low pressure cell that can sometimes create a cyclonic vortex |
|
|
Term
| Cyclonic vortex does this. |
|
Definition
| creates convective cells near the middle, causing a self-reinforcing cycle of heat and mass transfer |
|
|
Term
| lake effect precipitation |
|
Definition
| precipitation that happens as a result of a lake in the local area |
|
|
Term
|
Definition
|
|
Term
| In summer, cooler lake water does this. (regarding precipitation) |
|
Definition
| stabilizes air masses, thus reducing leeward precipitation |
|
|
Term
|
Definition
time related variability in precipitation
causes droughts and floods
occurs at many temporal scales, such as year to year and month to month |
|
|
Term
|
Definition
| plot of the depth of rainfall vs. a specified duration |
|
|
Term
| what k, es, and E do in the function of vapor pressure deficit (VPD) |
|
Definition
| -k increases as wind speed increases
-es increases with increasing temperature
-E increases with increasing vapor pressure deficit |
|
|
Term
|
Definition
| used to measure evaporation from open water in which the water levels are monitored |
|
|
Term
| why direct evaporation from soil is not important in forests |
|
Definition
| because the vegetative canopy and the organic debris on the forest floor shield the soil from direct solar radiation |
|
|
Term
| how mulching reduces evaporation from soil |
|
Definition
-keeping the soil temp lower
-slowing diffusion of water to atmosphere
-keeping relative humidity high at soil surface |
|
|
Term
| Plants use this as the source of carbon for building plant tissue. |
|
Definition
|
|
Term
|
Definition
| openings on leaves that open to exchange gas and close to protect the plant from dessication |
|
|
Term
| When a stomate is closed, the air in there becomes... |
|
Definition
| nearly saturated with water vapor |
|
|
Term
| The stomate closes when... |
|
Definition
| turgor pressure (the cell water pressure) drops |
|
|
Term
|
Definition
| transfer of water from plants to atmosphere |
|
|
Term
| Plants need to transpire to prevent... |
|
Definition
|
|
Term
| how wilt helps reduce overheating |
|
Definition
| causes the leaf to droop and avoid the sun's rays |
|
|
Term
| some mechanisms plants use to avoid overheating |
|
Definition
-transpiration
-wilt
-leaf petiole twisting
-fluttering in the wind |
|
|
Term
| how leaf petiole twisting helps a plant avoid overheating |
|
Definition
| causes leaf to turn sideways to the sun |
|
|
Term
|
Definition
-time varying measure of the plant's demand for water
-it increases with air temp, solar radiation, and relative leaf area |
|
|
Term
| Evaporate demand increases with... |
|
Definition
-air temperature
-solar radiation
-relative leaf area |
|
|
Term
|
Definition
| the ratio of the area of all the combined leaves to the area of ground over which those leaves grow |
|
|
Term
| potential evapotranspiration (PET) |
|
Definition
| the rate of combined evaporation and transpiration that occurs when soil water is unlimited |
|
|
Term
| actual evapotranspiration (AET) |
|
Definition
| actual amount of evapotranspiration loss per time for given area |
|
|
Term
|
Definition
| the rainfall that is caught by plant surfaces and evaporated directly back to atmosphere before it reaches the Earth's surface |
|
|
Term
| factors that can affect the amount of canopy interception |
|
Definition
-leaf area
-annual duration of cover |
|
|
Term
| potential evapotranspiration is determined only by... |
|
Definition
climactic variables, such as
-temperature
-solar radiation
-humidity
-wind |
|
|
Term
| why actual evapotranspiration is almost always less than potential evapotranspiration |
|
Definition
| because soil moisture is often limiting |
|
|
Term
| This is considered to be the simplest method to estimate potential evapotranspiration. |
|
Definition
|
|
Term
| how pan evaporation works |
|
Definition
-noting the changes in water level in a pan filled with water
-measures water loss in depth of water per day
-approximates evaporation for lakes |
|
|
Term
| actual evapotranspiration depends on... |
|
Definition
-crop (or vegetation)
-stage of growth
-soil moisture
-climactic variables |
|
|
Term
| some ways to estimate water use by plants |
|
Definition
-evaporation pans
-weighing lysimeters
-gas flux estimates
-watershed studies |
|
|
Term
|
Definition
| a soil microcosm used to monitor soil water content |
|
|
Term
| Using evaporation pans to measure evapotranspiration is simple, but it does not account for... |
|
Definition
| soil moisture or crop conditions |
|
|
Term
| P regarding calculating actual evapotranspiration using weighing lysometers |
|
Definition
|
|
Term
| R regarding calculating actual evapotranspiration using weighing lysometers |
|
Definition
|
|
Term
| how the gas flux method of measuring actual evapotranspiration works |
|
Definition
-plastic tent constructed over vegetation
-air blown thru tent
-evapotranspiration estimated by measuring the humidity and flow rate of the incoming and outgoing air |
|
|
Term
| what removal of forests does to base flows |
|
Definition
increases it
also slightly increases storm flows in the fall and spring |
|
|
Term
| how removing forests can benefit aquatic organisms |
|
Definition
|
|
Term
| Why did harvesting of forests in the very foggy foothills of the Cascade Mountains near Portland, Oregon reduced base flows? |
|
Definition
| because the trees caused water to condense out of the clouds and fog |
|
|
Term
|
Definition
| varies over the growing season as canopy develops and rooting depth increases |
|
|
Term
| how crop factor varies for annual plants |
|
Definition
-starts at about 0.1 before the seeds germinate
-increases to about 1.1 when the crops near their maximum size
-decreases again as the plants approach senescence |
|
|
Term
|
Definition
|
|
Term
| soil factor is estimated based on... |
|
Definition
| total available water in root zone (by horizon) |
|
|
Term
| amount of soil in water vs. evapotranspiration rate |
|
Definition
| as the amount of water in the soil becomes less, the evapotranspiration rate becomes less |
|
|
Term
| The soil factor (Ks) is calculated every day based on... |
|
Definition
|
|
Term
| It is usually best to irrigate when this amount of the maximum available water has vanished. |
|
Definition
| when 75% of the maximum available water has been removed from the soil (tensions reach about 1 bar, from moisture curve) |
|
|
Term
| The point at which you choose to irrigate depends on... |
|
Definition
| the type of plant and how mature the plant is |
|
|
Term
| how to calculate R (regarding water budget) |
|
Definition
|
|
Term
| Humans can do this regarding water budget. |
|
Definition
| change how water is partitioned between streamflow and evapotranspiration |
|
|
Term
|
Definition
| any water use that sends water to the atmosphere |
|
|
Term
| typical residential water usage in America |
|
Definition
| 75 gallons per person per day, mostly non-consumptive |
|
|
Term
| the question at the heart of the legal battles in the tri-state water wars between GA, AL, and FL |
|
Definition
| figuring out how much water is consumptively used by the upstream users |
|
|
Term
| one question that has vexed negotiators among GA, AL, and FL in the tri-state water wars |
|
Definition
| how much water put into septic systems returns to rivers and how much goes to the atmosphere |
|
|
Term
| Why is there more rainfall in mountains? |
|
Definition
|
|
Term
| apparent wetness ofa place is a matter of... |
|
Definition
|
|
Term
| metric uses this instead of acres |
|
Definition
|
|
Term
| infiltration vs. exfiltration |
|
Definition
| infiltration goes into soil; exfiltration goes out of soil |
|
|
Term
| what vegetation does for ground during rain |
|
Definition
| cushions ground against rain |
|
|
Term
| something bad fire does to soil (pertaining to infiltration) |
|
Definition
|
|
Term
| When a soil is frozen, it may do this to infiltration. |
|
Definition
|
|
Term
|
Definition
|
|
Term
| animals in desert burrow to this place |
|
Definition
|
|
Term
|
Definition
| regions near stream that are saturated and conduct water to stream |
|
|
Term
| pressure above water table |
|
Definition
|
|
Term
|
Definition
|
|
Term
| pressure below water table |
|
Definition
|
|
Term
|
Definition
| water moving down thru unsat layer |
|
|
Term
| When do water tables rise? |
|
Definition
|
|
Term
| Bt clay horizon can help create this |
|
Definition
|
|
Term
| This can happen if you irrigate too much. |
|
Definition
|
|
Term
|
Definition
| the area of land that contributes flow to a stream, lake, or river |
|
|
Term
| the largest watershed in Georgia |
|
Definition
|
|
Term
|
Definition
| the boundary line that separates 2 watersheds |
|
|
Term
| 2 subwatersheds within the Altamaha watershed |
|
Definition
|
|
Term
| A water budget defines... |
|
Definition
-how much rainfall evapotranspirates
-how much becomes streamflow
-how much leaves the basin as groundwater flow
-etc. |
|
|
Term
| usually, it is desirable to express the mean runoff as a flow with units of... |
|
Definition
|
|
Term
| mean annual flow vs. basin area |
|
Definition
| they increase linearly with each other |
|
|
Term
| why people build reservoirs |
|
Definition
| so water can be stored during high flow periods for use during low flow periods |
|
|
Term
|
Definition
| movement of water into the soil surface when water is applied or ponded on the soil surface, and it usually occurs during rainfall |
|
|
Term
| why infiltration is important |
|
Definition
| it determines whether surface runoff and erosion occur |
|
|
Term
|
Definition
aka vadose zone
the soil zone between the soil surface and the water table |
|
|
Term
|
Definition
aka unsaturated zone
the soil surface between the soil surface ad the water table |
|
|
Term
|
Definition
| the downward vertical movement of water thru the vadose (unsat) zone |
|
|
Term
|
Definition
| the rate at which water enters the soil surface |
|
|
Term
| maximum infiltration rate is greatest for... |
|
Definition
|
|
Term
| This happens when the rainfall rate exceeds the maximum infiltration rate. |
|
Definition
|
|
Term
| Water that doesn't infiltrate becomes... |
|
Definition
| overland flow aka direct runoff aka surface runoff |
|
|
Term
| saturated hydraulic conductivity vs. permeability |
|
Definition
| sat hydraulic conductivity=permeability |
|
|
Term
| the 2 main drivers of water flow in soil |
|
Definition
| gravity and soil capillary forces |
|
|
Term
|
Definition
| suck or wick water into the ground |
|
|
Term
| When the soil is completely saturated, the only driver of infiltration is... |
|
Definition
|
|
Term
| The soil's maximum infiltration rate is determined by... |
|
Definition
| the soil's permeability and the pressure driving infiltration |
|
|
Term
| why infiltration rates decrease quicker on bare soils |
|
Definition
| raindrop impact breaks up soil aggregates, creating finer particles that clog macropores at the soil surface, thus forming a crust |
|
|
Term
| the key to aggregate stability and why |
|
Definition
| humus because it stabilizes aggregates to a large degree |
|
|
Term
| 2 factors that affect aggregate stability |
|
Definition
|
|
Term
| soil textures that tend to suffer from low aggregate stability |
|
Definition
|
|
Term
| soil textures that don't crust |
|
Definition
|
|
Term
| sodium increases crusting due to... |
|
Definition
|
|
Term
|
Definition
| repulsion of clays on the microscale |
|
|
Term
| how mulch helps to prevent crusting |
|
Definition
| absorbing raindrop impact and letting the rain drip into the soil from the mulch |
|
|
Term
| practices that can reduce erosion in crop land |
|
Definition
| no till planting and leaving crop residues |
|
|
Term
| why sat hydraulic conductivities and infiltration rates in forest soils tend to be high |
|
Definition
-soil organisms creating macropores
-organic litter layers |
|
|
Term
|
Definition
| sat zone overlying a low permeability layer with an unsat zone below |
|
|
Term
| when infiltration rate at surface is determined by the infiltration rate at the Bt horizon |
|
Definition
| when there's a perched water table |
|
|
Term
| how temp affects infiltration |
|
Definition
-the colder, the more viscous the water
-the warmer, the less viscous the water |
|
|
Term
| Hydrologists divide streamflow into these 2 types of flow. |
|
Definition
|
|
Term
|
Definition
| that component that provides streamflow during low flow periods |
|
|
Term
|
Definition
| streamflow that occurs quickly in response to precipitation |
|
|
Term
|
Definition
-overland flow aka sheet flow aka surface runoff
-named after R.E. Horton |
|
|
Term
| the most obvious example of Hortonian/overland flow in Georgia |
|
Definition
| on streets and parking lots |
|
|
Term
| the difference between the rainfall rate and the infiltration rate |
|
Definition
| the amount of rain that runs off the landscape |
|
|
Term
|
Definition
-uptake of water by soil
-the result of capillary forces |
|
|
Term
|
Definition
sharp moisture difference between the newly wetted soils and the drier soils below them
moves downward during a storm |
|
|
Term
|
Definition
| lateral, shallow, subsurface flow that occurs on hillslopes w/ shallow permeable soil layers overlying low permeability layers |
|
|
Term
| interflow can occur as... |
|
Definition
|
|
Term
| When does interflow begin? |
|
Definition
| when the wetting fron crosses a soil layer and reaches the surface of the layer below |
|
|
Term
| Interflow is more important when... |
|
Definition
-soil layers are thin
-slopes are relatively large |
|
|
Term
| The Bt horizon can cause interflow because of... |
|
Definition
|
|
Term
| variable source area concept |
|
Definition
| sat areas that contribute to stormflow get bigger during rainstorms and smaller during drought |
|
|
Term
| Streamflow between storms comes from... |
|
Definition
-groundwater discharge
-interflow
-draining of water stored in lakes and wetlands |
|
|
Term
|
Definition
no
decreases between rainfall events |
|
|
Term
| effects of lower baseflow |
|
Definition
-less dilution of pollutant inputs resulting in higher contaminant concentrations
-less buffering- attenuation- for solar and atmospheric heating of the water |
|
|
Term
|
Definition
| this usually refers to water in sat soil layers |
|
|
Term
| Why might heavy use of ground water in a location detrimentally affect surface water resources? |
|
Definition
| because ground water is connected to surface water |
|
|
Term
|
Definition
-the elevation at which water stands in a dug hole
-the surface at which the water pressure is 0 |
|
|
Term
|
Definition
| small diameter well that is used only to observe the water table, not to extract usable water from the ground |
|
|
Term
| purity of water leaving the hillslope vs. how long it spends in the soil surface zone |
|
Definition
| the more time it spends there, the purer it becomes |
|
|
Term
| how soil and vegetative conditions dictate baseflows and flood peaks and volumes |
|
Definition
| determining how rainfall moves to streams |
|
|
Term
| why land managers want to maximize infiltration and minimize overland flow |
|
Definition
| to minimize flooding and maximize baseflows |
|
|
Term
| why some parts of the landscape grow trees or crop better |
|
Definition
| because topographic and geologic conditions cause water to accumulate in those areas |
|
|
Term
| Are landscapes ever in equilibrium? |
|
Definition
|
|
Term
| these 2 factors determine the number and distribution of streams and wetlands as well as other landscape features. |
|
Definition
| runoff patterns and groundwater flow |
|
|
Term
| The location and timing of landslides is largely driven by... |
|
Definition
| subsurface flow conditions, such as seepage areas on steep slopes |
|
|
Term
| The total hydraulic head of a water table is equal to... |
|
Definition
| the elevation of the water table |
|
|
Term
| the typical way to map a water table |
|
Definition
| to drill wells or piezometers throughout an area and interpolate between water elevations determined from the wells and from surface water elevations |
|
|
Term
| groundwater is replenished by the process of... |
|
Definition
| percolation, by which water moves downward by gravity towards the water table |
|
|
Term
|
Definition
| the water that successfully moves past the root zone and reaches the water table |
|
|
Term
| what stream outflows and ground water storage do during dry periods |
|
Definition
| stream outflows exceed rainfall inputs, and ground water storage is reduced to make up the difference |
|
|
Term
| what stream outflows and water tables do during wet periods |
|
Definition
| recharge to ground water exceeds discharge to streams, and water table rises |
|
|
Term
|
Definition
| thin band of soil in the vadose zone just above the water table that is fully saturated although the soil is held under negative pressure |
|
|
Term
| height of capillary rise vs. size of the intertestial pore space |
|
Definition
|
|
Term
| vadose zone (more correct definition) |
|
Definition
| area were the soil water is usually held under tension |
|
|
Term
| saturated zone aka phreatic zone |
|
Definition
| the zone beneath the water table where the pores are completely filled with water |
|
|
Term
|
Definition
-geologic media that is capable of transmitting significant quantities of water to a well or system of wells
-tends to have relatively large porosity, hydraulic conductivity, and volume (either depth, areal extent, or both) |
|
|
Term
| typical aquifer materials |
|
Definition
-gravel
-sand
-limestone
-highly fractured rock |
|
|
Term
|
Definition
| geologic media that entirely prevents fluid flow, meaning the hydraulic conductivity and porosity are zero |
|
|
Term
| true aquicludes are rare, but one example is... |
|
Definition
| an unfractured crystalline rock |
|
|
Term
|
Definition
-geologic medium with limited ability to transmit water
-has low hydraulic conductivity and/or porosity |
|
|
Term
|
Definition
|
|
Term
|
Definition
-aka water table aquifer aka surficial aquifer
-aquifer whose water table is connected to to the atmosphere thru the pores in the overlying vadose zone and which is not overlain by an aquitard or an aquiclude
-typically connected directly to surface water |
|
|
Term
| Does water in an unconfined aquifer fully saturate the aquifer media? What does this mean for the water in the unconfined aquifer? |
|
Definition
| no, meaning that the zone of saturation is free to move up or down |
|
|
Term
|
Definition
-saturated zone above the regional water table
-usually on top of an aquitard, such as a clay layer
-usually a temporary feature that forms during high recharge periods |
|
|
Term
|
Definition
-aquifer confined between overlying and underlying aquitards or aquicludes
-typically outcrops somewhere in the landscape, serving as recharge areas for confined aquifers |
|
|
Term
| Does water in a confined aquifer fully saturate the aquifer media? |
|
Definition
|
|
Term
| example of a confined aquifer |
|
Definition
| the Floridan aquifer, located below the coastal plain of Georgia |
|
|
Term
| Why are most confined aquifers, including the Floridan, not completely confined? |
|
Definition
| because there is some leakage thru the confining layers |
|
|
Term
|
Definition
| three dimensional surface defined by how high water rises in the wells or piezometers |
|
|
Term
| Are all water tables potentiometric surfaces? |
|
Definition
|
|
Term
| are all potentiometric surfaces water tables? |
|
Definition
|
|
Term
| the potentiometric surface of an unconfined aquifer |
|
Definition
|
|
Term
| the potentiometric surface of a confined aquifer |
|
Definition
| well above the top confining layer |
|
|
Term
|
Definition
| aquifer where the potentiometric surface is higher than the ground surface |
|
|
Term
| What sustains rivers during a drought? |
|
Definition
|
|
Term
|
Definition
plot of discharge (flow, streamflow) vs. time
-this is basically time vs. flow |
|
|
Term
|
Definition
| plot of flow just before, during, and after a storm |
|
|
Term
|
Definition
| maximum flow during the storm |
|
|
Term
|
Definition
| the time it takes to reach peak flow; flash flood has short time to peak |
|
|
Term
| peak flow pertaining to forests |
|
Definition
| forests tend to have smaller peaks and takes longer for peak to hit |
|
|
Term
|
Definition
| flows per unit area, usually a smaller peak and delayed for larger areas |
|
|
Term
|
Definition
| part of storm hydrograph before the peak |
|
|
Term
| Falling limb, or recession limb |
|
Definition
| part of hydrograph after peak |
|
|
Term
|
Definition
total amount of flow, the sum of all stormflow
-the volume is the area under the curve |
|
|
Term
|
Definition
part of hydrograph not associated with a storm, usually from lakes or
groundwater |
|
|
Term
| Why does the groundwater around Dalton tend to be carbonic? |
|
Definition
| because of the limestone there |
|
|
Term
| Are hydrographs seasonal? |
|
Definition
|
|
Term
| seasonal pattern of baseflow |
|
Definition
| more baseflow in winter and spring |
|
|
Term
| Gulf of Mexico tends to have a high isotopic signature due to |
|
Definition
|
|
Term
|
Definition
| o Cubic feet per second, cfs
o Gallons per minute, gpm
o Million gallons per day, mgd
-Athens uses about 15-20 mgd
o Acre-feet per day, AF/day
-1 acre2by 1 foot
o Cubic meters per second, cumec
o Liters per minute, Lpm |
|
|
Term
|
Definition
| another word for flow is discharge |
|
|
Term
|
Definition
|
|
Term
| Find v at multiple points across the stream using... |
|
Definition
|
|
Term
| flow in streams vs. levels |
|
Definition
| flow lower at lower levels and higher at higher levels |
|
|
Term
| productivity of storm drains in dry weather |
|
Definition
|
|
Term
|
Definition
-a measure of flood frequency
-Probability of an event, Tr = 1 / p |
|
|
Term
| Building a dam can do this regarding floods. |
|
Definition
| lower the flood probability (for small storms anyway) |
|
|
Term
| how hydrologists make a chart of the flood frequency |
|
Definition
by sorting observed floods (largest
to smallest), and then plotting their magnitude against a plotting statistic (e.g.,
Weibull, Gringarten) |
|
|
Term
| In the Curve Number Method, the variables are... |
|
Definition
| x variable is rainfall and y variable is runoff |
|
|
Term
| in the Curve Number Method, the different curve numbers are basically... |
|
Definition
|
|
Term
| curve number for parking lots |
|
Definition
|
|
Term
| curve number for ag areas |
|
Definition
|
|
Term
| what harvesting does regarding the hydrologic cycle |
|
Definition
| Harvesting reduces leaf area, decreasing ET, increasing water yield |
|
|
Term
|
Definition
-forest management
-ag land management
-urban land use management
-riparian buffers |
|
|
Term
| effects of forest management |
|
Definition
o Harvesting reduces leaf area, decreasing ET, increasing water yield
o Can increase runoff due to soil compaction (roads, yarding areas), reduction of
infiltration (burning)
o High lead or helicopter logging in steep areas to mitigate erosion
o Increases NPS (non-point source) pollution (water temperature, sediment, etc)
o BMPs (best management practices) to reduce NPS pollution
o SMZs (streamside management zones) are a BMP |
|
|
Term
| effects of ag land management |
|
Definition
o Plowing increases soil loss, no-till helps reduce this
-disturbs the soil more than forestry does
o Contour plowing, filter strips slow runoff
o Rotation of grazing, away from streams during winter, helps
-keep the grazing animals moving
o NMPs (nutrient management plans) are used to minimize fertilizer runoff
-done by not putting more fertilizer on the field than you need to |
|
|
Term
| effects of urban land use management |
|
Definition
o Stormwater management is key
-Increase detention and retention
-Detention basins, pervious surfaces (such as concrete water can go thru), rain gardens, green roofs, dry wells
o Channel structure is compromised
-Concrete & stone channels (straight) replace natural (winding) channels
LWD (large woody debris) and other organic debris recruitment (inputs)
and budgets change
+counterproductive to remove this |
|
|
Term
| effects of riparian buffers |
|
Definition
o Bank stability
o Pollutant filtration
o Denitrification
-too much nitrogen causes toxic algae
o Shade
-more habitat likes the shade
o Organic debris recruitment
-leaf-limb
o Large woody debris recruitment
o Wildlife habitat
-guild: community of specialists, such as grazers, shredders, colectors, predators
-99% of biological activity is in the riparian zone
o Aesthetic
o Social/Educational |
|
|
Term
|
Definition
usually slow (except glaciers, floods, fire)
-this is natural
-glaciers are basically giant bulldozers |
|
|
Term
| Fire does this to vegetation, which results in something pertaining to hydrology. |
|
Definition
| fire releases oil in vegetation; released oil puts varnish on soil, making water unable to infiltrate on soil |
|
|
Term
| how humans accelerate erosion |
|
Definition
o Humans accelerate erosion by land-disturbing activities such as overgrazing
o Compaction, reduced organic content, bare soil, fire |
|
|
Term
| how erosion can damage civilizations |
|
Definition
o Loss of soil productivity, collapse of empires
o Loss of harbors, navigation, trade |
|
|
Term
| navigation on Mississippi challenge because of... |
|
Definition
|
|
Term
| how SF Bay has been affected by erosion |
|
Definition
|
|
Term
| some examples of modern erosion |
|
Definition
o Soil loss reduces crop productivity (onsite problems)
o Siltation downstream (off-site problems) |
|
|
Term
|
Definition
from pipes
-example: industries |
|
|
Term
| nonpoint source discharges |
|
Definition
from landscape
-usually ag/urban |
|
|
Term
| an on site problem caused by erosion |
|
Definition
| Soil loss reduces crop productivity |
|
|
Term
| an off-site problem caused by erosion |
|
Definition
|
|
Term
|
Definition
o Suspension (moves in the air)
o Saltation (hops along the ground), “stinging sand”
o Creep (rolls along the ground)
-layers of particles moving across the surface |
|
|
Term
| how windbreaks can reduce wind erosion |
|
Definition
| by helping slow the air velocity near the ground |
|
|
Term
| examples of water erosion |
|
Definition
o Raindrop splash (impact energy, big drops are heavier, faster)
o Sheet erosion (overland flow, faster deeper water is worse)
-this where all the erosion gets started
o Rill erosion (concentrated flow in small rivulets)
-you can drive over a rill
-maybe 2-3 inches wide
o Gully erosion (concentrated flow in large, temporary channels)
-you can’t drive over a gully
o Channel erosion (concentrated flow in permanent channels)
-erosion settles into valleys as sediment |
|
|
Term
| details about raindrop splash erosion |
|
Definition
| Raindrop splash (impact energy, big drops are heavier, faster) |
|
|
Term
|
Definition
(overland flow, faster deeper water is worse)
-this where all the erosion gets started |
|
|
Term
|
Definition
(concentrated flow in small rivulets)
-you can drive over a rill
-maybe 2-3 inches wide |
|
|
Term
|
Definition
(concentrated flow in large, temporary channels)
-you can’t drive over a gully |
|
|
Term
|
Definition
(concentrated flow in permanent channels)
-erosion settles into valleys as sediment |
|
|
Term
| universal soil loss equation |
|
Definition
A = R x K x LS x C x P
o A: Annual Soil Loss factor (t/ac/yr)
-this is what we try to predict
o R: Rainfall factor
-Georgia has one of the biggest rainfall issues in the country
o K: Soil factor
-measure of how well the soil holds together when being rained on
o LS: Topographic factor
o C: Vegetation factor
-good vegetative cover is beneficial
o P: Conservation practices factor |
|
|
Term
| acceptable soil loss vs. total soil loss |
|
Definition
A < T?
o T (Acceptable Soil Loss) factor (t/ac)
-A=total soil loss |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| Turbidity does this to efforts to disinfect water. |
|
Definition
| turbidity hinders the effectiveness of chlorine and other disinfection |
|
|
Term
| the materials that make water turbid |
|
Definition
| mostly clay and the fine materials |
|
|
Term
| Does the state of Georgia distinguish between natural and artificial turbidity? |
|
Definition
|
|
Term
|
Definition
| JTUs, NTUs, FTUs, KTUs, Secchi |
|
|
Term
| the filterable solids in water |
|
Definition
|
|
Term
|
Definition
| load = concentration (mg/L) x flow (L/s) |
|
|
Term
| how to calculate total maximum daily yield |
|
Definition
| total maximum daily yield is load/area |
|
|
Term
|
Definition
| forestry is about the cleanest land use out there |
|
|
Term
|
Definition
the stuff flowing along the bottom of the stream
o Mass flux on & near bottom of stream |
|
|
Term
|
Definition
-lower bucket into stream and see how much sediment flows into there
Comparison of Measures |
|
|
Term
| some water sampling strategies |
|
Definition
-Location (depth, bank, distance)
-Stage (low, normal, high) |
|
|
Term
|
Definition
|
|
Term
|
Definition
|
|
Term
| strategies to prevent water erosion |
|
Definition
-Vegetative Cover
-Surface Stabilization
-Velocity Reduction
-Peak Flow Reduction
-Inspection and Maintenance |
|
|
Term
|
Definition
| help to settle solids out of water (opposite of dispersants) |
|
|
Term
| What can remove residual solids from water? |
|
Definition
|
|
Term
| This works to kill any residual pathogens. |
|
Definition
|
|
Term
| What sustains a river during a drought? |
|
Definition
| the slow release of ground water |
|
|
Term
| During wet periods, this happens regarding water levels in wells. |
|
Definition
| recharge to ground water raises the water levels in wells, and then moves towards streams |
|
|
Term
| the source, or contributing, area concept for streamflow generation |
|
Definition
| During wet periods, recharge to ground water raises the water levels in wells, and then moves towards streams. As the ground water levels rise, seepage areas next to streams begin to flow, because the water table is intersecting the ground surface at a higher elevation. The water flows out as seeps and springs along the bank of the river, as well as directly into the channel. |
|
|
Term
| ground water capture zone |
|
Definition
| the collection area for a well |
|
|
Term
|
Definition
| conservation area within the capture zone that protects the well from contamination |
|
|
Term
| the result of direct stormwater discharge |
|
Definition
| the reduction of infiltration and ground water recharge |
|
|
Term
| the result of groundwater recharge |
|
Definition
| reducing baseflow, thus switching water from baseflow to stormflow |
|
|
Term
| why direct stormwater disposal to streams is a big negative for stream health |
|
Definition
-stormflows have more power, thus causing more erosion
-shorter residence time, thus providing less opportunity for water quality improvement by decay and filtration of organic materials |
|
|
Term
| Where does the Floridan Aquifer outcrop and get recharge water? |
|
Definition
|
|
Term
| Why have there been cones of depression in the potentiometric surface around Savannah, Jesup, Brunswick, and Saint Mary's? |
|
Definition
| heavy pumping for industrial water supply |
|
|
Term
| What's causing salt water intrusion in the Floridan Aquifer? |
|
Definition
| cones of depression around the pulp mill wells drawing water from the ocean towards the coast |
|
|
Term
| These can be used to estimate the flow thru sections of the aquifer. |
|
Definition
| potentiometric map, along with Darcy's Law, an estimate of saturated hydraulic conductivity, K's, and an estimate of the aquifer depth |
|
|
Term
|
Definition
| the water that's essentially "borrowed" and returned to the river |
|
|
Term
|
Definition
| water that's used and doesn't return to the river |
|
|
Term
| consumptive water use vs. return flow among city dwellers |
|
Definition
| 20% consumptive and 80% return flow |
|
|
Term
| Why is water use in ag largely consumptive? |
|
Definition
| irrigation, since the whole point of irrigation is to supply transpiration demand |
|
|
Term
| the time of year we have the lowest streamflow |
|
Definition
| late summer and early fall |
|
|
Term
| What time of year do we have the highest water demand? |
|
Definition
| late summer and early fall (principally for lawn irrigation) |
|
|
Term
| Civilization has developed these 2 ways to solve the mismatch between water demand and streamflow behavior. |
|
Definition
| dams and groundwater pumping |
|
|
Term
| one of the reasons we build dams |
|
Definition
| to store high streamflows so that water can be saved and used when streamflows would otherwise be too low to meet demands |
|
|
Term
|
Definition
| because it is more convenient to rural landowners and also because groundwater can provide a consistent supply of water throughout most years as long as total groundwater use does not exceed percolation |
|
|
Term
| Total groundwater use must not exceed... |
|
Definition
|
|
Term
| Flows are dependent on these factors. |
|
Definition
-climate
-soils
-geology
-vegetation
-topography |
|
|
Term
| These things can affect channel structure, behavior, and habitat. |
|
Definition
-forestry
-ag
-landscaping
-urbanization
-other human activities |
|
|
Term
| How alterations to vegetation and soils can affect streams |
|
Definition
-affect streamflow generation processes
-streamflow behavior
-sediment loading
-woody debris loading
these can have significant effects on biota |
|
|
Term
| This affects the type of sediment found in a stream and the runoff characteristics. |
|
Definition
| the geology and soils of a river basin |
|
|
Term
| Why do Piedmont streams tend to have excessive sand? |
|
Definition
| because the saprolite in which they flow breaks down easily and Piedmont soils are highly erodible and contribute substantial amounts of surface soil to streams |
|
|
Term
| how humans can change the runoff characteristics and thus alter the form of rivers and streams |
|
Definition
| by changing the physical character of the soils by compaction and plowing |
|
|
Term
| These things can affect channel dynamics, substrate composition, and channel morphology (e.g. number, depth, and volume of pools) |
|
Definition
-type of sediment
-amount of sediment entering a stream
-capacity of a stream to transport sediment |
|
|
Term
| These things can greatly increase fine sediment loading to channels. |
|
Definition
-surface erosion from plowed fields
-logging roads
-new construction areas
-trampled fields
livestock trampling also destabilizes banks |
|
|
Term
| Sediment is transported as... |
|
Definition
-bedload
-suspended load
-dissolved load |
|
|
Term
|
Definition
water moving over the bed of a stream exerts this force on bottom sediments
increases with velocity and depth of water |
|
|
Term
|
Definition
| every particle has a critical shear stress at which it will begin to move |
|
|
Term
| particle size vs. critical shear stress |
|
Definition
| the bigger the particle, the greater the critical shear stress |
|
|
Term
| why mountain streams tend to have gravel or cobble bottoms |
|
Definition
| because all the sand and finer particles have been flushed out |
|
|
Term
|
Definition
| describes the relative sediment moving ability of a stream |
|
|
Term
| A channel is in equilibrium when... |
|
Definition
| sediment supply rate equals sediment transport capacity |
|
|
Term
| A channel is aggrading when... |
|
Definition
| channel and valley are rising because sediment supply exceeds transport |
|
|
Term
| A channel is degrading when... |
|
Definition
| channel and valley are eroding, or incising, because sediment transport exceeds sediment supply |
|
|
Term
|
Definition
|
|
Term
| Why are most Piedmont streams not in equilibrium? |
|
Definition
| because of past sediment inputs from erosion of poorly managed cotton fields |
|
|
Term
| These channels tend to be eroding. |
|
Definition
|
|
Term
| These channels tend to be aggrading. |
|
Definition
| larger order channels, that is, above 2nd order |
|
|
Term
| Why do Piedmont streams tend to have relatively flat channel bottoms? |
|
Definition
| because they are aggrading |
|
|
Term
| info about the typical sandy substrate in Piedmont stream beds |
|
Definition
-highly mobile
-poor habitat for benthic macroinvertibrates and for mussels |
|
|
Term
| This affects flood routing. |
|
Definition
| channel confinement or valley cross-sections |
|
|
Term
| how humane can alter valley shapes |
|
Definition
| building dikes and levees, which reduce flood storage, increase downstream flows, and eliminate alluvial floodplain deposition |
|
|
Term
| how riparian vegetation benefits streams |
|
Definition
| roots help hold streambanks in place |
|
|
Term
| Removal of streamside trees does this to streams. |
|
Definition
-destabilizes banks
-increases channel migration |
|
|
Term
| what forested riparian zones do for streams |
|
Definition
| create a moist, cool microclimate that holds down stream temperatures |
|
|
Term
| what overhanging vegetation does for channels |
|
Definition
| provides shade, cover, and organic debris to the channel |
|
|
Term
| Fallen trees may do this for a river. |
|
Definition
| create cover for fish and cause pools to scour in the channel bed |
|
|
Term
| Elimination of riparian forests reduces... |
|
Definition
|
|
Term
| how riparian vegetation can prevent eutrophication of streams and lakes |
|
Definition
| taking up nutrients in runoff from adjacent land uses |
|
|
Term
| landscape factors that govern channel morphology and behavior |
|
Definition
-topography/topology
-geology
-climate
-soil layering
-vegetation (riparian and upslope)
-flows
-sediment loading
-woody debris
-keystone species
-time since and type of previous disturbances
-biogeographic setting |
|
|
Term
| how topography/topology affects channel morphology and behavior |
|
Definition
| Channel slope (along with flow) drives the sediment transport capacity of a stream. Steep channels tend to have rocky and coarse substrate. Flat channels tend to have sand and fine sediment substrates. Valley side slopes affect sediment production from upslope activities and can also affect woody debris recruitment to the channel system. Valley confinement controls the amount of energy in the channel vs. energy expended on the floodplain during high flows. |
|
|
Term
| how geology affects channel morphology and behavior |
|
Definition
| The parent geology of a basin determines the type of sediment available to the channel system. Highly weathered granite produces poor gravel. Channels in weathered gravel tend to be sandy. Young basalt produces highly resistant, long-lasting gravel. The parent material is also a factor in soil conditions. Local discontinuities in rock type can directly affect channel structure. In the Piedmont of Georgia, outcrops of rock resistant to weathering produce shoal habitat in rivers where the water rushes over exposed hard rock. These shoals are home to a different biotic community than is present in the nearby channel reaches. |
|
|
Term
| how climate affects channel morphology and behavior |
|
Definition
| The characteristics and amount of rainfall in a basin, as well as the potential evapotranspiration in a basin, determine the amount of flow in a stream per unit area. They also affect the stream density in a basin. |
|
|
Term
| how soil layering affects channel morphology and behavior |
|
Definition
| Depths and hydrologic characteristics of soil horizons exert strong controls on the runoff generating processes in a basin. Organic content and aggregate stability affect the frequency and amount of soil erosion that may transport sediments to streams. Soil cohesion affects the stability of streambanks. |
|
|
Term
| how vegetation (riparian and upslope) affects channel morphology and behavior |
|
Definition
| The quantity and type of vegetation on the uplands determines the amount of surface runoff and erosion from the hillsides. It also affects the actual evapotranspiration with consequences for stream baseflows. Riparian vegetation provides bank stability, shade, and organic debris inputs to the channel. |
|
|
Term
| how flows affect channel morphology and behavior |
|
Definition
| The temporal characteristics of flows and the total volume of flow, along with channel slope, are the dominant drivers of sediment movement, channel scour, and woody debris transport. They also affect the survival of fish during the low flow period, the flushing of fish from the channel during high flows, and the scour and transport of fish eggs. The amount and velocity of flow affects DO concentrations and water temperatures during the summer. |
|
|
Term
| how sediment loading affects channel morphology and behavior |
|
Definition
| The amount of sediment introduced to the stream affects whether a channel is aggrading, incising, or maintaining a constant level. The amount and type of sediment affects the occurrence of pool habitat and the amount of interstitial habitat in the channel and bed material. High levels of sediment loading cause aggradation of the channel and floodplains as well as frequent scour and bed material. Reductions in sediment loading cause channel erosion through either incision or bank erosion. |
|
|
Term
| how woody debris affects channel morphology and behavior |
|
Definition
| Woody debris acts as scour elements in channels, meaning that pools tend to form around large woody debris during high flow events. During baseflows, these pools are important habitat features for fish. Woody debris also provides cover for fish, and provides substrate for the growth of macroinvertebrates (fish food). Art Benke, an aquatic entomologist, has determined that woody debris is responsible for over half the macroinvertebrate production in blackwater rivers. |
|
|
Term
| how keystone species affect channel morphology and behavior |
|
Definition
| Beaver dams introduce sediment traps throughout the channel system and break the channel gradient into steps. Beavers alter floodplain deposition processes, water chemistry, and flood routing. Similarly, humans modify sediment transport and flows using levees, dams, channel straightening, etc. |
|
|
Term
| some examples of keystone species |
|
Definition
-humans
-beavers
-nutria
-salmon |
|
|
Term
| how time since and type of previous disturbances affects channel morphology and behavior |
|
Definition
| There is a continuum of possible disturbances in channel systems. Large floods occur relatively frequently and reshape the channel system. Large wildfires introduce pulses of sediment. Direct glaciation alters soils, topography, and hydrology. Glacial episodes, even far from the areas of glaciation, affect climate and coastline locations (altering the base level of river outlets). Debris flows initiated during extreme storms reshape mountain channels. Disease outbreaks can result in accelerated woody debris inputs. All channels are subject to disturbance. |
|
|
Term
| how biogeographic setting affects channel morphology and behavior |
|
Definition
| If two unmodified streams in southern Chile and western Oregon featured very similar channel conditions in terms of bed sediments, woody debris frequency, pool and riffle distributions, flows, and water temperatures, they would still support very different biological communities because the pool of plants and animals available to colonize the habitat would be different. These animals would have different life history requirements and thus different sensitivities to physical inputs. In actuality, Europeans introduced Pacific Northwest trout and salmon to southern Chile a hundred years ago, and these fish maintain wild populations in Chile. This is an example of a keystone species modifying the biogeographic setting of a stream. |
|
|
Term
|
Definition
| a plot of discharge- flow rate- and stage- water level in the stream- versus time |
|
|
Term
|
Definition
|
|
Term
|
Definition
| water level in the stream |
|
|
Term
|
Definition
| graph of flow before, during, and after a specific storm |
|
|
Term
|
Definition
| the maximum flow during the storm |
|
|
Term
| Why does tyhe unit-area flow decrease as the basin gets bigger |
|
Definition
1: decreasing channel slope as the basin gets bigger
2: storage within the channel and the river
3: the basinwide rainfall rate generally decreases as it is averaged over a larger area |
|
|
Term
| The peak of the hydrograph is generally produced by... |
|
Definition
| surface runoff, either by partial area contribution or Hortonian overland flow as well as direct precipitation on the channels |
|
|
Term
| Why do stormflows typically rise quickly? |
|
Definition
| because most areas producing surface runoff are near the channels |
|
|
Term
|
Definition
| the steep advance portion of the hydrograph that reflects the onset of runoff |
|
|
Term
| falling limb or recession |
|
Definition
| the decreasing portion of the stormflow hydrograph |
|
|
Term
| This dominates the falling limb of the hydrograph. |
|
Definition
|
|
Term
|
Definition
the total volume of streamflow associated with that storm
can be determined from the area under the hydrograph when the hydrograph plots flow (not stage) vs. time |
|
|
Term
|
Definition
| the flow before and after the storm |
|
|
Term
| Baseflow is generated principally by... |
|
Definition
| ground water discharge and unsat interflow |
|
|
Term
| These months are when we typically have the lowest water supply and the highest water demand. |
|
Definition
|
|
Term
| why American Hydrologists typically measure streamflow in cubic feet per second (cfs) |
|
Definition
| because baseflow in small streams is usually only a few cfs and sometimes only a fraction of a cfs |
|
|
Term
| For small flows, we use this unit. |
|
Definition
|
|
Term
| Why is water flow at the bottom of the stream usually slower than water flow at the top of the stream? |
|
Definition
|
|
Term
| depth at which to measure velocity of flow for smaller streams, that is, streams less than 1 meter deep |
|
Definition
|
|
Term
| depths at which to measure velocity of flow for deeper streams |
|
Definition
|
|
Term
| Why are flow velocities lower along the edges than in the middle? |
|
Definition
|
|
Term
|
Definition
| an instrument that measures the water velocity |
|
|
Term
| how the USGS measures streamflow |
|
Definition
| Their gaes measurethe depth of flow, also called the stage, every hour, and they convert this depth into a discharge with a rating curve |
|
|
Term
|
Definition
| a graph of discharge versus stage developed by manually measuring flow at a variety of stages and then interpolating between the points (or extrapolating beyond the points). |
|
|
Term
| when a rating curve has to be re-developed |
|
Definition
| after any event that causes that channel cross-section to change, such as deposition or scour of sediment after a large flood |
|
|
Term
| Manning's equation allows hydrologists and hydraulic engineers to do this. |
|
Definition
| estimate flow in a channel without measuring it |
|
|
Term
|
Definition
| the length of the channel bottom in contact with water measured perpendicular to the channel |
|
|
Term
| Manning's equation predicts this in a channel. |
|
Definition
|
|
Term
|
Definition
| developed by ranking the peak annual flows from largest to smallest, assigning a plot position to each flow, and then plotting the flows in a semi-log plot |
|
|
Term
| In the Southeast, flow recurrence curves typically have this separating flows caused by hurricanes from those caused by other types of rainstorms. |
|
Definition
|
|
Term
| These are used to estimate flood flows for ungaged streams. |
|
Definition
| regional regression equations |
|
|
Term
| These equations can be used to estimate flood flows and design drainage structures when there is no gage data to analyze |
|
Definition
| regional regression equations |
|
|
Term
| Why does flood discharge increase more slowly than basin area? |
|
Definition
| because average storm precipitation is lower over large areas than over small areas |
|
|
Term
| Channels form in a way that... |
|
Definition
| a stable geometry results which is in equilibrium with relatively frequent sediment moving flows |
|
|
Term
| the most common method used in the U.S. for predicting stormflow peaks, volumes, and hydrographs for precipitation events |
|
Definition
| the Curve Number method (aka TR-55) |
|
|
Term
| The Curve Number method is useful for... |
|
Definition
| designing ditches, culverts, detention ponds, and water quality treatment facilities |
|
|
Term
| The graphical version of the Curve Number method relies on... |
|
Definition
|
|
Term
|
Definition
| representative storm hydrograph for 1 mm (or 1 cm or 1 inch) of runoff for a specific basin |
|
|
Term
| To calculate a peak flow rate for a storm, one simply... |
|
Definition
| scales the unit hydrograph peak by the true rainfall and the true basin area |
|
|
Term
| The Curve Number method allows direct estimation of... |
|
Definition
| Total Runoff Depth, Q, expressed as depth over the watershed area |
|
|
Term
| Total Runoff Depth, Q, is expressed as... |
|
Definition
| depth over the watershed area |
|
|
Term
| No runoff is produced until... |
|
Definition
| rainfall exceeds initial abstraction |
|
|
Term
| Why is the water storage for a paved surface not zero? |
|
Definition
| The roughness, cracks, and puddles on a paved surface allow for a small amount of storage. |
|
|
Term
| Curve numbers can be adjusted based on... |
|
Definition
-cover
-soil type
-hydrologic condition
-antecedent moisture conditions |
|
|
Term
| how forests promote infiltration |
|
Definition
-build organic layers at the soil surface
-create well-mixed and highly porous soils
-increase the hydraulic roughness
-develop extensive macropore networks within the root zone |
|
|
Term
| Forests intercept more rainfall because of... |
|
Definition
| their high leaf area indicies |
|
|
Term
| Forests soils tend to be drier than other soils at the onset of storms and their available soil storage is higher. Why? |
|
Definition
-high leaf area indicies
-high relative evapotranspiration |
|
|
Term
| Why do forests tend to have relatively low peak flows, storm flow volumes, and total annual flows? |
|
Definition
-infiltration
-high leaf area indicies
-high relative evapotranspiration rates |
|
|
Term
| how timber harvest increases mean annual flow and storm flow volumes |
|
Definition
| reducing interception and evapotranspiration |
|
|
Term
| The effects of forest harvesting on peak flows depends on... |
|
Definition
|
|
Term
| The effects of harvest itself depends on... |
|
Definition
| the degree of soil compaction |
|
|
Term
| Slash burning following forest clear cutting is likely to initiate... |
|
Definition
| surface runoff and erosion |
|
|
Term
| how slash fires may affect the landscape |
|
Definition
| If slash fires burn hot, they eliminate the mulch layer from the soil surface. During intense rainstorms, the soils will seal, overland flow will occur, and rills and gullies may form. If the fires burn very hot, they can actually create water repellent soils because the soil surface will be coated by a polymer residue from the fire. |
|
|
Term
| some ways the hydrologic and soil erosion effects of timber management can be mitigated |
|
Definition
-road runoff dispersed onto planar or convex slopes so that sediment can be filtered out and water can infiltrate into the soil
-high lead yarding can eliminate soil compaction
-felling/yarding equipment with large, soft tires can reduce soil compaction
-helicopter logging reduces road disturbances, but comes at a great expense |
|
|
Term
| how road runoff dispersed onto planar or convex slopes can mitigate the effects of timber management |
|
Definition
| sediment can be filtered out and water can infiltrate into the soil |
|
|
Term
| how high lead yarding can mitigate the effects of timber management |
|
Definition
| by eliminating soil compaction |
|
|
Term
| how felling/yarding equipment with large, soft tires can mitigate the effects of timber management |
|
Definition
| by reducing soil compaction |
|
|
Term
| how helicopter logging can mitigate the effects of timber management |
|
Definition
| by reducing road disturbances, but comes at a great expense |
|
|
Term
| benefits of vegetated buffers and variable source areas |
|
Definition
| can allow water to re-infiltrate or can filter water before it reaches the channel system |
|
|
Term
| benefits of not burning after harvest |
|
Definition
| leaving the mulch and small woody debris on the ground surface encourages infiltration and prevents surface erosion |
|
|
Term
| effect of forests on water temperatures |
|
Definition
| keeps the temperatures cooler by shading the stream |
|
|
Term
| effect of removing riparian forests |
|
Definition
| increases solar radiation on channel and increases air temp above channel, both of which increase water temp |
|
|
Term
| effect of forest clear-cutting |
|
Definition
-increases radiation to the soil floor
-net result: higher soil temp in summer, cooler in winter |
|
|
Term
| The direct effects of forests harvest on stream temp can be mitigated by... |
|
Definition
| leaving forested buffers on streams and wetlands to protect microclimate around channels |
|
|
Term
| The effect of ground water temps can be reduced by... |
|
Definition
|
|
Term
| Most non-point source pollution problems from silvicultural activities arise from... |
|
Definition
| the creation of overland flow from areas of bare or compacted soil |
|
|
Term
| the basic recommendations shared by all forestry best management practices (BMP's) |
|
Definition
-minimize bare ground coverage and soil compaction
-separate bare ground from surface waters
-separate fertilizer and pesticide application from surface waters
-inhibit hydraulic connections between bare ground and surface waters
-provide a forested buffer around streams
-engineer stable road surfaces and stream crossings
-avoid harvest on steep (>45%) and convergent slopes |
|
|
Term
| Specifics of BMP guidelines vary with respect to things like... |
|
Definition
-width recommendations for streamside management zones (SMZ's)
-allowance of thinning within SMZ's
-spacing recommendations for water diversions on logging roads
-road surfacing accommodations
-etc. |
|
|
Term
| why overland flow is common in plowed croplands |
|
Definition
| because the soil surface forms a crust that inhibits infiltration during rainfall |
|
|
Term
| Plowing under stubble does this to soil. |
|
Definition
| eliminates organic protection of soil surface |
|
|
Term
| Plowing soil does this to soil. |
|
Definition
-eliminates macropores
-homogenizes soil
-reduces infiltration |
|
|
Term
| Loss of organic layer does this to soil. |
|
Definition
-reduces soil storage
-reduces infiltration |
|
|
Term
| why soil storage and infiltration rates are lower in pastures than in forests, even if grass cover is maintained |
|
Definition
-livestock grazing compacts soil and reduces infiltration
-root system of pasture grasses not as deep as forests, thus reducing transpiration losses |
|
|
Term
| how grazing can cause direct channel effects |
|
Definition
| if livestock are not fenced away from streams and wetlands |
|
|
Term
| how loss of vegetation affects banks |
|
Definition
| makes them less stable and more likely to erode during high flows as well as reduce cover and shade for aquatic organisms |
|
|
Term
| how the hydrologic effect of pastures can be minimized |
|
Definition
| by rotating livestock between pastures to prevent denuding the soils and allow vegetation to re-establish itself |
|
|
Term
| why it's good to fence livestock away from streams |
|
Definition
| allows the creation of a forested riparian buffer which can filter runoff from the adjacent pasture and prevent direct channel effects |
|
|
Term
| how the hydrologic effects of row crops can be reduced |
|
Definition
-maintaining high organic contents in the soil
-leaving stubble on the ground
-good soil conservation practices
-for some crops, such as cotton, no till cultivation will nearly eliminate surface runoff while still providing good yields |
|
|
Term
| how urbanization affects streams and aquatic systems |
|
Definition
-increasing peak flow rates and durations
-introducing pollutants into surface waters
-eliminating forested riparian vegetation
-directly disturbing channel structure
-sometimes by reducing low flows in streams |
|
|
Term
| effect of higher flows on channels and banks |
|
Definition
| increases channel and bank erosion |
|
|
Term
| effect of riparian forest removal |
|
Definition
-reduces the resistance of banks to erosion
-reduces natural filtration of pollutants from adjoining land uses |
|
|
Term
| the net water quality result of residential and commercial development |
|
Definition
increasing the loading of:
-nutrients
-fine sediments
-oils and greases
-metals
-bacteria
-some toxic organics (including pesticides and herbicides)
to surface waters |
|
|
Term
| why modification of the land surface during urbanization changes the type and magnitude of surface runoff processes |
|
Definition
-vegetation clearing
-soil compaction
-ditching and draining
-covering the land with impervious roofs and roads |
|
|
Term
| one reason why it might be a bad idea to make a stream hydraulically smoother |
|
Definition
| because cleaning of woody debris and straightening or deepening of stream increases the efficiency of the channel, transmitting the floodwave downstream more quickly and with less retardation by the channel |
|
|
Term
| how urbanization can worsen the summer low flow situation |
|
Definition
-Impervious surfaces and lawns reduce summer low flows and recharge to ground water.
-can be exacerbated by elimination of natural storage features such as wetlands |
|
|
Term
| urbanization's largest effect on water quality |
|
Definition
| the fine sediments and nutrients released during land clearing and grading |
|
|
Term
| how the State of Georgia deals with the fine sediments and nutrients released during land clearing and grading |
|
Definition
| has a grading ordinance which requires temporary erosion and sediment control during construction |
|
|
Term
| Runoff from roads and parking lots often contains these pollutants. |
|
Definition
-fine sediments
-oils
-greases and fuels from vehicles
-metals
-sometimes solvents and organics (from improper disposal into the storm drain system) |
|
|
Term
| Runoff from landscaped areas commonly contains these pollutants. |
|
Definition
-nutrients from excessive fertilization
-pesticides
-herbicides |
|
|
Term
| Forested riparian areas provide these important functions for fish-bearing streams. |
|
Definition
1: stabilizing streambanks
2: filtering pollutants from adjacent lands
3: maintaining a cool microclimate that reduces water temp
4: providing woody debris which improves habitat |
|
|
Term
| how streams in urbanized areas can experience rapid and uncontrolled incision of the stream bed |
|
Definition
| usually in response to an increase in the flow rate combined with specific combinations of gradient, substrate, and reduced in-channel vegetation |
|
|
Term
| when the effects of urbanization on streams are reduced |
|
Definition
| -when effective construction sediment controls, stormwater detention, and water quality treatment are applied to developments
-natural storage features such as wetlands and floodplains are maintained
-adequate riparian buffers are left on streams and wetlands, impervious surfaces are limited in extent
-when citizens are educated about water quality protection thru such programs as stormdrain stenciling |
|
|
Term
|
Definition
| the channel adjacent terrestrial areas where the presence of the stream and high water tables are primary drivers of vegetation and soil characteristics |
|
|
Term
| how riparian vegetation affects channel conditions |
|
Definition
| altering microclimate and providing organic inputs to stream system |
|
|
Term
| some names for riparian protection areas |
|
Definition
-riparian zones
-riparian management zones
-buffers
-filter strips
-streamside management zones (SMZ's) |
|
|
Term
| benefits of riparian buffers |
|
Definition
-bank stability
-pollutant filtration
-denitrification
-shade
-organic debris recruitment
-large woody debris recruitment
-wildlife habitat
-aesthetic
-social/educational |
|
|
Term
| how riparian buffers improve bank stability |
|
Definition
-roots of streambank trees help hold banks together
+when these trees are removed, streambanks often collapse, initiating a cycle of sedimentation and erosion in the channel
-buffer needs to be 15+ feet wide to maintain bank stability |
|
|
Term
| How wide does a riparian buffer have to be to maintain bank stability? |
|
Definition
|
|
Term
| how riparian buffers improve pollutant filtration |
|
Definition
| As dispersed overland streamflow enters a forested streamside buffer, it encounters organic matter and hydraulic roughness, created by the leaf litter, twigs, sticks, and plant roots. The organic matter adsorbs some chemicals, and the hydraulic roughness slows down the flow. The drop in flow velocity allows clay and silt particles to settle out, along with other chemicals adsorbed to the particles. Depending on the gradient and length of adjacent slopes, a buffer needs to be 30-60 ft wide to provide adequate filtration. |
|
|
Term
| How wide does a riparian buffer have to be to provide adequate filtration? |
|
Definition
| Depending on the gradient and length of adjacent slopes, a buffer needs to be 30-60 ft wide to provide adequate filtration. |
|
|
Term
| how riparian buffers improve denitrification |
|
Definition
| Shallow groundwater moving thru the root zones of floodplains is subject to significant denitrification. Removal of floodplain vegetation reduces the denitrification function of a floodplain. |
|
|
Term
| what removal of floodplain vegetation does to the denitrification function of a floodplain |
|
Definition
|
|
Term
| how riparian buffers improve shade |
|
Definition
| Along small and mid-sized streams, riparian trees provide significant shade over the channel, thus reducing the amount of solar radiation reaching the channel so summer stream temps are lower and potential dissolved oxygen levels are higher. Buffers need to be 30+ wide to provide good shade and microclimate control, but benefits increase up to 100 ft. |
|
|
Term
| How wide does a riparian buffer have to be to provide good shade and microclimate control? |
|
Definition
|
|
Term
| how riparian buffers improve organic debris recruitment |
|
Definition
| River ecosystems are founded upon the leaves, conifer needles, and twigs that fall into the channel. An important function of riparian trees is providing coarse organic matter to the stream system. Buffers only need to encompass half the crown diameter of full-grown trees to provide this function. |
|
|
Term
| an important function of riparian trees |
|
Definition
| providing coarse organic matter to the stream system |
|
|
Term
| how riparian buffers improve large woody debris recruitment |
|
Definition
| Large woody debris plays many important ecological functions in stream channels. It helps scour pools, a favored habitat for many fish. It creates substrate for macroinvertebrate and algae growth, and it forms cover for fish. It also traps and sorts sediment, creating more habitat complexity. Woody debris comes from fallen limbs and fallen trees. The width of a riparian buffer should be equal to half a mature tree height to provide good woody debris recruitment. |
|
|
Term
| How wide does a riparian buffer have to be to provide good woody debris recruitment? |
|
Definition
| equal to half a mature tree height |
|
|
Term
| how riparian buffers improve wildlife habitat |
|
Definition
| Many organisms, most prominently certain species of amphibians and birds, use both aquatic and terrestrial habitat in close proximity. Maintaining a healthy forested riparian corridor creates important wildlife habitat. The habitat benefits of riparian buffers increase out to 300 ft. |
|
|
Term
| aesthetic benefits of riparian buffers |
|
Definition
-more attractive than streams w/o riparian buffers
-beautify ag, suburban, and urban landscapes |
|
|
Term
| social/educational benefits of riparian buffers |
|
Definition
-a favorite place for children to play
-provide Green Space for local residents to relax, walk, and learn |
|
|
Term
| some human activities that expose bare soil to the kinetic energy of rainfall and accelerate erosion |
|
Definition
-forest clearing
-grazing
-plowing
-grading soils |
|
|
Term
| Compaction reduces this in soil. |
|
Definition
|
|
Term
| Loss of soil organic content reduces this in soil. |
|
Definition
|
|
Term
| the biggest threat to ag and forestry production worldwide |
|
Definition
|
|
Term
| the basis for much of the wealth on this planet |
|
Definition
|
|
Term
| Early civilizations in Mesopotamia, Egypt, and China relied on this to bring water to their crops. |
|
Definition
|
|
Term
| What happened to canals that contributed to the eventual collapse of early civilizations? |
|
Definition
| Siltation from upstream deposited into these canals. |
|
|
Term
| why kudzu was brought to this country |
|
Definition
| to control soil erosion, which it does effectively |
|
|
Term
| Erosion rates are usually expressed as... |
|
Definition
| inches of topsoil per year or tons per acre per year |
|
|
Term
| tolerable rate of erosion according to NRCS |
|
Definition
|
|
Term
| how soil in the B horizon turns into A horizon |
|
Definition
|
|
Term
| How much topsoil was lost during the cotton era? |
|
Definition
| up to 12 inches, especially in the Piedmont |
|
|
Term
| What happened to the soil that was lost int eh Piedmont during the cotton era (1830-1930)? |
|
Definition
ended up in the streams, rivers, and valley bottoms of the Piedmont
Piedmont streams have not always run red and brown from clay |
|
|
Term
| conditions of streams prior to cotton farming |
|
Definition
clear streams founded on rock with patches of gravel and sand
freshwater mussels were common in these conditions |
|
|
Term
| The soils in Georgia could no longer sustain row crop agriculture, so Georgia converted to this. |
|
Definition
| forest production, since it could still support pine |
|
|
Term
| How the restoration of our soil's productivity is possible. |
|
Definition
| thru organic matter additions and no-till farming |
|
|
Term
| what suspended sediment does to streams |
|
Definition
-can foul fish gills
-increase stream temp
-reduce feeding efficiency |
|
|
Term
| how suspended sediments increase stream temps |
|
Definition
| by increasing the absorbance of solar radiation |
|
|
Term
| how suspended sediments reduce feeding efficiency |
|
Definition
| by making it harder for fish to see prey |
|
|
Term
| Georgia Soil and Water Conservation Commission |
|
Definition
-formed to protect, conserve, and improve the soil and water resources for the State of Georgia
-goal is to make Georgia a better place for its citizens thru the wise use and protection of basic soil and water resources and to achieve practical water quality goals |
|
|
Term
| Georgia Forestry Commission |
|
Definition
| provides leadership, service, and education in protection, management, and wise use of Georgia's forest resources |
|
|
Term
| U.S. Natural Resources Conservation Service |
|
Definition
| provides leadership in a partnership effort to help people conserve, maintain, and improve our natural resources and environment |
|
|
Term
| U.N. Food and Agriculture Organization |
|
Definition
| has a mandate to raise levels of nutrition and standards of living, to improve ag productivity, and to better the condition of rural populations |
|
|
Term
| how turbidity adversely affects aquatic ecosystems |
|
Definition
| by decreasing depth to the compensation point |
|
|
Term
|
Definition
| the depth within the water column where the use of oxygen exceeds oxygen production |
|
|
Term
| Sediments carry these things that reduce water quality. |
|
Definition
-pesticides
-nutrients (especially phosphorus)
-heavy metals that are adsorbed onto the sediment particles and ca desorb in the streams |
|
|
Term
|
Definition
| water discharged into a stream from a pipe or or structure, usually associated with a city or industry |
|
|
Term
| nonpoint-source discharge |
|
Definition
| water discharged over a wide area, not coming from a pipe, usually associated with farms, homes, forests, etc. |
|
|
Term
| The net sediment in storage is a function of... |
|
Definition
| the sediment that is slowly leaving, as well as the sediment that is being contributed by modern land uses |
|
|
Term
|
Definition
|
|
Term
| Erosion consists of these two processes. |
|
Definition
|
|
Term
| detachment (erosion process) |
|
Definition
| removal of fine particles from aggregates; necessary step in erosion because the aggregates are too big to move |
|
|
Term
| transport (erosion process) |
|
Definition
| After detachment has occurred, transport is the movement of detached particles off the source area (field, construction project, bare-soiled clear cut) and eventually to surface waters |
|
|
Term
| where wind erosion is a major problem |
|
Definition
| in arid/semi-arid climates, because only dry soil blows in the wind |
|
|
Term
| The Dust Bowl was precipitated by... |
|
Definition
| intensive farming of marginal lands which were then desiccated by an extended drought with high winds |
|
|
Term
| The Dust Bowl spawned this movement. |
|
Definition
| the soil conservation movement in the US |
|
|
Term
| 3 ways wind can move soils |
|
Definition
-suspension
-saltation
-creep |
|
|
Term
|
Definition
| When very fine particles, silt and clay, are picked up by the wind and carried in the atmosphere. These particles essentially float on the wind and are carried high in the atmosphere. They may be deposited hundreds and even thousands miles away from where they were picked up. Deposition areas of wind blown soils may eventually build up layers of loess soils. |
|
|
Term
|
Definition
| The bouncing of medium and fine sand over the ground surface, usually about 0.5 to 3 ft in the air. When the particles fall back to the ground, their impact begins to lift other particles which begin to saltate. Because of these chain reactions, saltation becomes more severe the longer the high winds blow. If you have ever been to the beach on a day with strong winds, you have probably experienced saltation of stinging sand |
|
|
Term
|
Definition
| The rolling of coarse sands along the ground surface. Creep is responsible for the formation and movement of sand dunes in bare deserts. Creeping soils can be trapped with soil fences, and the fences on the dunes at the beach are meant to hold sand on the dunes |
|
|
Term
| Creeping soils can be trapped with... |
|
Definition
| soil fences, and the fences on the dunes at the beach are meant to hold sand on the dunes. |
|
|
Term
| Conservation practices to control wind erosion are designed to... |
|
Definition
| keep soils covered or to reduce wind velocity at soil surface |
|
|
Term
| methods used by wheat farmers to protect the soil surface from wind erosion |
|
Definition
| -anchored crop residues, left by no-till or stubble cropping |
|
|
Term
| how contour tillage can be used to control wind erosion |
|
Definition
-planting rows perpendicular to prevailing wind direction
-also planting windbreaks of trees perpendicular to thew prevailing wind direction |
|
|
Term
|
Definition
|
|
Term
| Fluvial erosion is generated by these 2 mechanisms. |
|
Definition
-raindrop impact
-concentrated flow |
|
|
Term
|
Definition
| causes detachment of fine particles from soil aggregates, and it is also the initiator of transport |
|
|
Term
| the major detaching mechanism on bare soils |
|
Definition
|
|
Term
|
Definition
| small channels merge into larger channels leading to this, causing both detachment and transport of soil particles |
|
|
Term
| The soil transport capacity of channels is determined by... |
|
Definition
|
|
Term
|
Definition
| erosion caused by soil detachment caused by the energy from raindrop impacts |
|
|
Term
|
Definition
-movement of sediment across the soil surface that is not in a channel, rill, or gully
-doesn't involve channel flow
-picks up erosion caused by raindrop splash as well as loose sediments on the soil surface
-uniformly removes soil from a planar area
-causes relatively low rates of erosion on flat land with good mulch
-thin film of flow delivers sediment to rills |
|
|
Term
|
Definition
| When the contributing area becomes large enough, the thin layer of overland flow starts to cut small channels (1-6" deep) into soil surface. Rills are created by concentrated flow. Rills are formed when the velocity of the flow on the soil is large enough to create shear stresses sufficient to detach and entrain soil particles. Rills transport the sediment dislodged by sheet erosion and carry it off the eroding surface. Rills also pick up and transport additional sediment from the walls and bottoms of the rills themselves. Rill erosion is especially severe on slopes greater than 6%, and rill erosion causes high rates of erosion. |
|
|
Term
|
Definition
| Rill erosion on a larger scale. Gullies can become enormous, such as Providence Canyon in SW GA. The basic definition of a gully is a rill that is too deep to cross with farm machinery. Gullies form from 2 processes. One way they form is when rills come together and concentrate even more flow. Again, the gully forms and grows because of shear stresses exerted by fast moving water flowing in the channel. A second way that gullies can form is when ground water seeps out near a spring and washes out a channel below the spring. Stream banks and stream bottoms also erode during high flows due to the shear stress of fast moving water. Almost all streams become turbid (carry a large amount of suspended sediment) during high flows because of the detachment of sediment from the channel banks and bottom. |
|
|
Term
|
Definition
| Flow in channels can cause erosion on the bed of the river (called scour) as well as along the banks. Bank erosion is most severe on outside bends of the river, and less severe on the inside bends. Woody debris can slow channel erosion by forming small dams that decrease the water velocity. On the other hand, woody debris might increase channel erosion by concentrating water into areas where erosion might be accelerated. |
|
|
Term
|
Definition
| erosion on the bed of the river |
|
|
Term
| Bank erosion is most severe on ______ and least severe on ______. |
|
Definition
outside bends
inside bends |
|
|
Term
| how woody debris can slow channel erosion |
|
Definition
| by forming small dams that decrease the water velocity |
|
|
Term
| how woody debris can increase channel erosion |
|
Definition
| by concentrating water into areas where erosion might be accelerated |
|
|
Term
| why the universal soil loss equation (USLE) is useful |
|
Definition
| used to estimate soil losses and sediment production |
|
|
Term
|
Definition
| gives the value for a given location by interpolating between the isoerodent lines |
|
|
Term
|
Definition
| lines of equal rainfall erosivity |
|
|
Term
|
Definition
| estimated from the surface soil texture and organic matter content |
|
|
Term
|
Definition
based on the steepness and length of slope on a particular field
if terraced, L becomes the terrace length, but S stays the same |
|
|
Term
|
Definition
shallow channels cut into the soil along the contour at fixed intervals down a hill slope- often used to divert water horizontally off a field area to a ditch or waterway
can help reduce the rilling that occurs at the base of long slopes
In USLE, terracing reduces the L part of the LS factor |
|
|
Term
|
Definition
| reflects the influence of plant canopy and surface litter/mulch on the erosion process, and can be taken from a number of different tables, depending on the type of crop |
|
|
Term
| conventional tillage vs. no-till |
|
Definition
| Conventional tillage means plowing/disking to produce a smooth surface of exposed soil, while no-till results in planting directly in crop residues, leaving surface mulched. |
|
|
Term
| when to set the conservation practices factor, P, to P=1 |
|
Definition
| when planting is not done along the contour of a field |
|
|
Term
| the soil loss tolerance or T factor |
|
Definition
| the amount of soil loss that is considered to be excessive |
|
|
Term
| The T factor is reduced by 1 t/ac/yr if... |
|
Definition
| the texture is stony, gravely, or generally high in fragments |
|
|
Term
| the natural rate of soil erosion |
|
Definition
|
|
Term
| 3 types of sediment measurement in streams |
|
Definition
-turbidity
-total suspended solids
-bedload solids |
|
|
Term
|
Definition
| measure of the clarity of a water sample |
|
|
Term
| Before the advent of modern light scattering devices, this was used to measure turbidity. |
|
Definition
| the Jackson candle turbidimeter in Jackson Turbidity Units (JTU's) |
|
|
Term
| mephelometric turbidity unit (NTU) |
|
Definition
| measure of light scatter in a hydrazine sulfate and hexamethylenetetramine solution that forms a formazine suspension |
|
|
Term
|
Definition
| used to determine the optical clarity of deep water bodies |
|
|
Term
| how the mineral and organic fractions of suspended sediment can be determined |
|
Definition
| by filtering, and then combusting the sample st 550°C for 1 hour to remove the organic material |
|
|
Term
| another way to determine the suspended sediment load in a water sample |
|
Definition
| using a hydrometer to measure the density of the sediment solution |
|
|
Term
|
Definition
| sediments transported along or near the bed of a stream |
|
|
Term
| locations where erosion and sedimentation control strategies can focus on monitoring sediment |
|
Definition
-at eroding source, at the boundary of the disturbed site
-at some point downstream of the disturbed site |
|
|
Term
| On-site estimates of sediment production can be readily obtained by... |
|
Definition
| measurement of the volume of soil lost from the site |
|
|
Term
| Gully and rill volumes due to erosion are determined by... |
|
Definition
| making aerial cross-section and length measurements |
|
|
Term
| how surface erosion can be measured |
|
Definition
| using fixed pins or stakes and measuring elevation before and after an erosion event |
|
|
Term
| When were the greatest sediment discharges observed? |
|
Definition
| when large amounts of runoff occurred from lands with disturbed soils |
|
|
Term
| Models describing sediment transport and discharge also incorporate... |
|
Definition
| channel storages and in-channel sediment supplies |
|
|
Term
| sediment storage vs. observed sediment discharge |
|
Definition
| smaller sediment storages can result in lower observed sediment discharges |
|
|
Term
| types of on-site sediment control methods to prevent and control erosion and sedimentation |
|
Definition
-vegetative cover
-surface stabilization
-velocity reduction
-peak flow reduction
-inspection and maintenance |
|
|
Term
| types of vegetative cover that can reduce erosion |
|
Definition
| vegetation and plant residues, i.e. mulch |
|
|
Term
| how vegetative cover reduces erosion |
|
Definition
| protects soil from raindrop impact |
|
|
Term
| why no-tillage methods were developed |
|
Definition
| to investigate the costs and benefits of growing plants w/o plowing |
|
|
Term
|
Definition
-reduces runoff and erosion by up to 90%
-saves money on plowing |
|
|
Term
|
Definition
-requires special planters
-more herbicides and pesticides needed to reduce competition and maintain yields
-soil compaction sometimes a problem |
|
|
Term
| the major sediment issues in forestry |
|
Definition
-minimizing the risks of landslides in steep terrains
-controlling runoff and sediment from logging roads |
|
|
Term
| how loggers can reduce erosion |
|
Definition
| by chopping and spreading vegetative residues w/o burning, thus providing a mulch layer |
|
|
Term
| the goal of erosion control |
|
Definition
|
|
Term
| sediment concentrations in Georgia streams vs. discharge stage |
|
Definition
| strong correlation; suspended sediment concentrations increase with discharge rate |
|
|
Term
| When do overland flow and erosion occur in natural forest streams? |
|
Definition
| when the cover is removed and or in exceptional storm events |
|
|
Term
| This is usually the culprit in soil erosion. |
|
Definition
|
|
Term
| why exposed soil is usually the culprit in soil erosion |
|
Definition
| allows crusting that generates overland flow and leads to sheet, then rill, then gully erosion, in succession |
|
|
Term
| Do conservation practices such as contouring and terracing increase infiltration? |
|
Definition
|
|
Term
| Protecting this reduces overland flow. |
|
Definition
|
|
Term
|
Definition
-chopping and spreading slash
-using herbicides to control weeds
-In forestry, this is much better than bulldozing and burning after harvest. |
|
|
Term
| how urban construction managers can reduce erosion |
|
Definition
-minimize exposed soil
-use straw or mulch
-reduce flow lengths with hay bales and silt fences
-collect runoff in sediment basins to allow sediment to settle before discharge |
|
|
Term
| Much of the turbidity in Piedmont streams is from... |
|
Definition
|
|
Term
|
Definition
-zone of undisturbed vegetation that surrounds the disturbed site and any water courses that cross the site
-has been shown to be effective in reducing erosion
-the intent is to intercept and capture sediment in runoff on the site |
|
|
Term
| The effects of forest harvesting and other activities that utilize unsurfaced roads can be most significantly reduced by... |
|
Definition
-rehabilitating cut and fill slopes using seed without mulch
-seeding with mulch
-hydroseeding |
|
|
Term
| Vegetative buffers may be less effective if... |
|
Definition
| a significant channel has formed before it reaches the buffer strip |
|
|
Term
| how gypsum (CaSO4) can improve the hydrologic properties of soil |
|
Definition
| can be applied on the soil surface to prevent dispersion and to form a crust that promotes infiltration and resists impact erosion and overland flow erosion |
|
|
Term
|
Definition
|
|
Term
| some things that can be done to reduce stream sediment concentration |
|
Definition
-using a dosing system to inject a polyelectrolyte stream
-using geotextile sediment mats to trap and maintain sediments during ditch cleaning and construction |
|
|
Term
| After a geotextile mat is full of sediment, it can be... |
|
Definition
| moved, staked to the streambank, seeded, mulched, and left to provide streambank stabilization |
|
|
Term
| The sediment mat is made of... |
|
Definition
| burlap, excelsior, and and jute mesh |
|
|
Term
| effectiveness of the sediment map |
|
Definition
| traps 80% of the disturbed sediment |
|
|
Term
| how geotextile mats are good for plants |
|
Definition
| make good germination beds for grass seed |
|
|
Term
| the primary intent of velocity reduction devices |
|
Definition
| to reduce the erosive potential of overland flow |
|
|
Term
| some velocity reduction methods |
|
Definition
-silt fences
-strategic placement of large obstacles, such as hay or straw bales
-rip-rap (gravel and large stones
-contour furrowing and terraces |
|
|
Term
|
Definition
-have been used to collect sediment or to divert overland flow into buffer strips
-ineffective on steep slopes but can't contain channelized flows due to their inability to withstand significant water flow |
|
|
Term
| To be effective, silt fences must be... |
|
Definition
| run along the contour of the topography, never parallel to the slope |
|
|
Term
| when hay bales are most effective at reducing erosion |
|
Definition
| when used in conjunction w/ silt fences or other and positioned upstream of the silt fences so that they roperly divert water to a buffer strip or retaining basin |
|
|
Term
|
Definition
-the use of gravel and large stones to reduce erosion
-should be used where water is concentrated into channels and where the channel gradient is steep enough to cause soil erosion |
|
|
Term
| contour furrowing and terraces |
|
Definition
-used extensively by ag, reduces the flow slope by creating detention storage and by diverting flow that would normally occur downslope into channels that flow along the contour
-should have a minor slope that allows flow to be diverted across the diverted area at reduced velocities into a buffer strip or a retaining basin |
|
|
Term
| good effects of reducing peak flow |
|
Definition
| The subsequent augmentation of baseflow benefits aquatic ecosystems by increasing streamflow during droughts, improving water quality, reducing instream erosion, lowering stream temps, and increasing stream aesthetics. |
|
|
Term
|
Definition
| these are used to settle sediments eroded from upgradient surfaces, as well as to minimize the likelihood of erosion downstream |
|
|
Term
| the use of stage-dependent discharge structures |
|
Definition
| to maximize the efficiency of the basin |
|
|
Term
| use of coagulants in water treatment |
|
Definition
| to flocculate clays in detention basins prior to release |
|
|
Term
| some coagulants used in the water treatment industry |
|
Definition
| -lime
-alum (Al(OH)3)
-polyelectrolytes
-cationic polymers
-anionic polymers
-nonionic polymers
-ferric sulfate (FeSO4)
-ferric chloride (FeCl2)
the utility of each treatment varies depending upon the natural pH and sediment type |
|
|
Term
| how wetlands work to reduce peak flows and reduce sediment |
|
Definition
| naturally filter out sediments, but are vulnerable to destruction by excessive sedimentation |
|
|
Term
| how places downstream can be protected from sedimentation |
|
Definition
| if alternate sites upstream can be engineered to collect and trap sediments |
|
|
Term
| why water spreading should be an essential feature of all erosion control measures |
|
Definition
| Due to the erosive nature of concentrated water over channels, water should be encouraged to spread over the largest, flattest area possible to increase infiltration, reduce velocity, and the associated sediment transport |
|
|
Term
| Contouring and terracing are intended to... |
|
Definition
reduce the slope length and steepness of a field and thereby control the speed of runoff
This is basically done by controlling the direction of runoff so that it travels over either low gradient slopes or it travels in channels constructed to withstand the flow energy |
|
|
Term
|
Definition
-orients rows of crops perpendicular to the natural runoff flow path and forces water to flow off the field along the contour
-slows the velocity of the runoff and traps sediment within the microtopography |
|
|
Term
|
Definition
-uses alternate strips of crops on contour to trap sediments
-the idea is to have strips of crops that provide good cover in between strips of crops that do not provide good cover
-used on long even slopes |
|
|
Term
|
Definition
-extreme form of contouring
-involves creating channels along the contours to collect runoff and divert it off the field into an erosion-resistant waterway |
|
|
Term
| the basic goal of terracing |
|
Definition
| to reduce the effective slope length so that runoff is collected before rills form |
|
|
Term
| Most U.S. cities get their tap water from... |
|
Definition
|
|
Term
|
Definition
| chemicals added to water in water treatment plants to make the sediment particles stick together and settle to the bottom faster |
|
|
Term
| What happens to the sediments after they settle out of the water in a water treatment plant? |
|
Definition
-piped as a slurry to a settling basin where they are periodically dredged
-the dredge material is then applied to farm fields or forests |
|
|
Term
| How do water treatment plants remove organic material from water? |
|
Definition
-passing it thru a bed of sand and crushed anthracite coal
-organic materials get adsorbed onto the surface of the coal particles |
|
|
Term
| how bacteria and viruses are rendered harmless in the water treatment process |
|
Definition
-water passed thru a bank of high intensity UV light that shatters the RNA and DNA molecules within the pathogens, rendering them unable to replicate
-small amount of chlorine added to prevent pathogens from growing in the pipe system |
|
|
Term
| Why is phosphorus added to tap water? |
|
Definition
| to stabilize the mineral scale that forms on the inside of the pipes |
|
|
Term
| what reduced erosion means for water treatment |
|
Definition
| reduces the cost of water treatment |
|
|
