# Shared Flashcard Set

## Details

Hydrology
Ground Water: infiltration, flow nets, Darcie law,stream response to water input events, zones
68
Geology
Undergraduate 2
11/20/2010

## Cards Return to Set Details

Term
 What is the infiltration capacity?
Definition
 It is the point at which the soil becomes saturated.
Term
 How does suction relate to the infiltration rate?
Definition
 As infiltration decreases, suction also decreases and vice versa.
Term
 What are the properties of soil that affect infiltration rates?
Definition
 porosity, water, minerals
Term
 What is the availably water capacity?
Definition
 It is the area on a graph between field capacity and the wilting point.
Term
 What type of soil can hold the most water, ie has the highest water capacity?
Definition
 Clay.
Term
 How do you calculate the available water capacity?
Definition
 (AWC) = (Water content - Wilting point) times rooting depth.
Term
 What is Darcy's Law for unsaturated flow?
Definition
 q = -K(dh/dl)
Term
 What are controls on (q) flow rate through medium?
Definition
 What content that changes as the hydrophilic conductivity changes and suction head changes. Soil type
Term
 What is hydrological conductivity?
Definition
 It is the ability of water to move through porous medium.
Term
 Why does hydrolic conductivity change with moister content?
Definition
 As water penetrates, it fills up pores first then infiltrates.
Term
 How does the tension head (suction) act in GW?
Definition
 When the water is saturated the tentino head is = 0. When the ground is less then saturated it is < 0. When the ground water is over saturated it is > 0.
Term
 What type of soil can suck up more water?
Definition
 Dry, pores soil.
Term
 How do you calculate the hydrolic head, what is it composed of?
Definition
 The tension + elevation head.
Term
 What is the difference between field capacity (fc) and wilting point (wp)?
Definition
 fc is controlled by gravity and porosity. The only way to go below fc is by the wilting point. The wiling point is controlled by plant suction.
Term
 What is hysteresis?
Definition
 It is a graph that shows the start and then the end of something. Like the wetting of soil and then the draining.
Term
 What would you expect to see on a hysteresis of infiltration?
Definition
 The suction would rapidly decrease by the amount of water would not change a lot because smaller pore spaces are filling up first. larger pore spaces start to fill so there would be an increase in water content and suction would not decrease as rapidly. As it returns to field capacity the little pores can block the big pores to cause the soil to drain at a liner rate.
Term
 What are characteristics of aquifers?
Definition
 Aquifer flow is heterogeneous (K is not constant), are anisotropee (K is different in different directions).
Term
 What is the assumption when making flow maps?
Definition
 The hydrolic head (k) is constant, the flow is constant and doesn't change directions.
Term
 What are flow lines?
Definition
 The lines in which the under water flows. Parallel to the water table.
Term
 What are equiproportional lines?
Definition
 Run perpendicular to the water table. Depicts hydrolic head (h)
Term
 What is hygroscopic water?
Definition
 The water the sticks to minerals, and can not be sucked up by plants.
Term
 What is capillary fringe? Why does it exist?
Definition
 The spot just about the water table. It occurs because the unsaturated soil on top of the water table acts like a sponge and sucks up some water.
Term
 What is the intermediate vadose zone?
Definition
 The intermediate vadose zone is between the capillary fringe and the root zone.
Term
 What is the root zone?
Definition
 Also known as the riparian zone, is the layer that has roots in it.
Term
 What is the ground what budget?
Definition
 input = recharge. output = pumping + run off + ET. Input - Output = change in storage.
Term
 What happens around a well?
Definition
 Cone of depression in the water table.
Term
 What happens to recharge/discharge/ and storage when you pump water out of a well?
Definition
 The recharge rate increases. The discharge and storage decrease because we are de-watering the aquifer.
Term
 How do you calculate the cone depression (CD)?
Definition
 CD = volume pumped / SY (significant yield)
Term
 What happens when we pump water out of a confined aquifer?
Definition
 The CD will be much larger, but it does not mean we are directly lowering the water table.
Term
 What is subsidence?
Definition
 It occurs when the land settles from the loss or water, it will not be able to fill back up with water.
Term
 What is the riparian zone?
Definition
 Transition between plant and aqua zone. There is greater biodiversity.
Term
 What are importants of the riparian zone?
Definition
 controls the chemicals that flow into the stream, stream bank stability, transitional ecosystem, buffer
Term
 What is the hyporheic zone?
Definition
 "mixing zone" 3 different ways to define it. Hydrology: Surface, temperatureChemistry: oxygen and conductivityBiology: greater biodiversity
Term
 Where can upwelling zones occur?
Definition
 In the hyporheic zone
Term
 What are the mechanisms that generate run off?
Definition
 Channel PPT and GW flow
Term
 What are different techniques to calculate overland flow?
Definition
 Hortonian and Saturation Excess
Term
 What is Hortonian overflow and what conditions could you use it?
Definition
 It is the main way water gets into the stream in arrid or urban areas. It ocurres when the water can not infiltrate the soil, so the water just flows directly in the river.
Term
 What is subsurface land flow (sssf)and where does it occur?
Definition
 It occurs when there is ground water mounding (riparian zones), difference in permiability in the ground, or macropores.
Term
 What is saturation overland flow?
Definition
 It occurs when the water table comes higher then the river causing the water to first drain down the land.
Term
 What is the (VSA) or the variable source area concept?
Definition
 It is the porpotion that generates watershed overland flow. It changes with time. As the source are flow increases the stream response increases.
Term
 What run off generation mechanism would have the highest rate of run off?
Definition
 (HOF) Hortonian - then Sat over flow - then subsurface land flow.
Term
 What are the three factors that influence the velocity of a stream?
Definition
 slope, depth (hydrolic radios), and friction (texture).
Term
 What is transmissivity when thinking about water flowing in 3d?
Definition
 It is the depth times hydrolic conductivity.
Term
 What is the importance of ground water?
Definition
 -80 to 90 percent of fresh water-base flow supports river and lakes-stabilizes temperature.-water qaulity-riparian vegitation
Term
 What are the difference between ground water and stream water?
Definition
 Ground water has a greater residential time.
Term
 How is ground water and surface water related?
Definition
 There is a seasonal change in both. Water quality of the river is dirrectly influenced by the water quality of the GW.
Term
 What happens when the water table is lower than the stream?
Definition
 The stream well start to recharge the water table, causing the river to lower.
Term
 What is an aquifer?
Definition
 It contains soils or rocks, that contain GW that can supply wells.
Term
 What are the two types of Aquifers and how do they differ?
Definition
 Unconfined aquifer has direct contact with the atmosphere. Confined Aquifer is confined by an aquaclude and does not have direct contact with the atmosphere.
Term
 What is an aquaclude?
Definition
 It is an impermeable layer in the ground. It confines aquifers.
Term
 What are two types of wells used to measure GW and how do they differ?
Definition
 Piezometer and well. A Piezometer is pressurized so the water level is higher than the actual GW and a well is not, so the water level in the well is the same level as the water table
Term
 How do you calculate specific yield (SY) in an unconfined aquifer?
Definition
 SY = Volume water released / serface area * the change in hydrolic head.
Term
 What is specific yield?
Definition
 It is the percent of water obtained from the soil.
Term
 If a soil is more pores, does it have a higher specific yield (SY)?
Definition
 No!
Term
 What type of soil has the highest SY and what has the highest porosity?
Definition
 Sand has the highest SY and clay has the greatest porosity.
Term
 How do you calculate the SY in a confined aquifer?
Definition
 SY is equal to the change in pressure in the confined case.
Term
 What has more water per unit head, confined or unconfined aquifer and why?
Definition
 Unconfined aquifer has more because we are draining the water table directly.
Term
 What does (q) represent in Darcie's law?
Definition
 q = specific discharge
Term
 What does K represent in Darcie's law?
Definition
 Hydrolic Conductivity or saturated conductivity.
Term
 How do you calculate the total volume of discharge (Q)?
Definition
 Q = q * Area
Term
 What happens when you graph specific discharge (q) over the Hydraulic gradient (dh/dl)
Definition
 It should be a liner graph. The slope of the line is K (hydraulic conductivity.)
Term
 What re examples of aquiclude material?
Definition
 clays and shale
Term
 [image]
Definition
 This graph shows one way to calculate K hydraulic conductivity.
Term
 what is an aquifuge?
Definition
 Layer of soil that does not contain or transmit water
Term
 in water case (confined or unconfined) would you use a piezometer?
Definition
 confined!
Term
 What happens to the hydraulic conductivity (k) as the moister content increases?
Definition
 K increases as well.
Term
 How do you separate quick flow graphs from base flow graphs?
Definition
 You can do so by looking at the chemical composition of the water in the water table and the chemical composition of the rain fall.
Term
 When does overland flow occure?
Definition
 When the rate of rain fall exceeds the infiltration rate.
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