Infiltration Soil Water

Question 1

Terrasphere

Answer 1

water moves through the soil in response to both gravity and tension

Question 2

Gravity

Answer 2

water flows to center of earth, downward

Question 3

Tension

Answer 3

water is adhesive and holds onto soil; under stress; pulled in opposite directions

Question 4

Soil Formation

Answer 4

takes hundreds of years to make 1 inch

Question 5

Soil Formation Factors

Answer 5

parent material, time, climate, geology, biological agents

Question 6

Parent Material

Answer 6

igneous, sedimentary, metamorphic

Question 7

Climate

Answer 7

black, red, rocky, solid

Question 8

“Black” Horizon

Answer 8

leaching zone organics here, most roots, susceptible to erosion

Question 9

“Red” Horizon

Answer 9

accumulation zone, nutrients collect here

Question 10

“Rocky” Horizon

Answer 10

weathered bedrock here

Question 11

“Solid” Horizon

Answer 11

bedrock here

Question 12

Moves Soil

Answer 12

water, wind, glaciers, finger lakes region

Question 13

Residual Soil

Answer 13

soil material which is the result of weathering and decomposition of rocks that has not been transported from its original place

Question 14

Colluvial Soil

Answer 14

loose, unconsolidated sediments that have been deposited at the base of hillslopes by either rainwash, sheetwash, slow continuous downslope creep, or a variable combination of these processes

Question 15

Marine

Answer 15

of, found in, or produced by the sea

Question 16

Lacustrine

Answer 16

relating to or associated with lakes

Question 17

Alluvial

Answer 17

moving water

Question 18

Fluvioglacial

Answer 18

water from ice

Question 19

Glacial

Answer 19

ice

Question 20

Aeolian

Answer 20

wind

Question 21

Soil Texture Classes

Answer 21

silt, clay, sand, loam

Question 22

Characterizing Soil

Answer 22

texture class, particle size, porosity, hydrologic soil group

Question 23

Particle Size Example

Answer 23

fine gravel > coarse sand > medium sand > fine sand > silt and clay

Question 24

Why do we need particle size standards?

Answer 24

The amount of open space between the particles influences how easily water moves through a soil and how much water the soil will hold

Question 25

Soils are Non-homogeneous

Answer 25

usually a mix of sands, silts, clays (texture classes)

Question 26

Soil Texture Triangle Example

Answer 26

30% Clay, 10% Silt, 60% Sand

Question 27

Bucket of Soil

Answer 27

dirt (solid), water (liquid), air (gas)

Question 28

Total Volume

Answer 28

Volume Water + Volume Air + Volume Solids

Question 29

Soil Water

Answer 29

water in soil; fills the voids and pushes out the gases

Question 30

Hydroscopic Water

Answer 30

typically not removed

Question 31

Depth

Answer 31

how we talk about volume of water

Question 32

Porosity

Answer 32

volume of voids / total = n ; quality or degree of having minute spaces or holes through which liquid or air may pass

Question 33

Density of most Soil Particles

Answer 33

160-170 lbs./ft^3 or 2.6-2.75 g/cm^3

Question 34

Typical Porosity

Answer 34

30-60%

Question 35

Infiltration

Answer 35

precipitation seeping into the ground; from atmosphere to the soil

Question 36

Infiltration Units

Answer 36

length or length/time; total or rate

Question 37

Measuring Infiltration

Answer 37

nearly impossible, would disturb the sample; can be inferred

Question 38

What we want to know about infiltration

Answer 38

how much enters the soil

Question 39

Percolation

Answer 39

downward movement of water through the soil profile

Question 40

Percolating Water

Answer 40

can move as a saturated front under the influence of gravity OR can move as an unsaturated front due to capillary forces

Question 41

Smaller Pores

Answer 41

fill first and empty last

Question 42

Bigger Pores

Answer 42

fill last and empty first

Question 43

Why Big Pores Empty First

Answer 43

water is too heavy to hold onto soil/rock/gravel

Question 44

Engineering

Answer 44

interested in strenth of soil and amount of runoff (and timing of it)

Question 45

Field Capacity

Answer 45

difference between saturation and wilting point; how much can soil hold before it runs (%)

Question 46

Wilting Point

Answer 46

most water has left/is gone; plant can no longer suck more water up, and droop; farmers starting irrigation process (expensive)

Question 47

Clayey

Answer 47

low permeability and high runoff

Question 48

Loamy

Answer 48

moderate permeability

Question 49

Sandy

Answer 49

rapid permeability and low runoff

Question 50

What affects infiltration?

Answer 50

surface characteristics: vegetation, blacktop, forest, roofs

Question 51

Bare Ground vs Crops: Bare Ground

Answer 51

increases runoff and flood risk; decreases infiltration

Question 52

Bare Ground vs Crops: Crops

Answer 52

increases infiltration; decrease runoff and flood risk

Question 53

Water Table

Answer 53

as it rains, it rises/increases; where water is at underground; wells drill to this and past it

Question 54

Average per Capita

Answer 54

80 gal/person/day

Question 55

How does the infiltration rate change during a storm?

Answer 55

decreases over time; depends on type of soil and surface

Question 56

Measure infiltration rate of soil

Answer 56

worry more about the runoff

Question 57

Infiltration Rate Methods

Answer 57

Horton, Green-Ampt, SCS Curve Number

Question 58

Constant Percentage Method

Answer 58

doesn't change over time, not truly realistic; assumes watershed is capable of infiltrating value proportional to rainfall intensity; 25% infiltration and 75% runoff

Question 59

Constant Percentage Method Equation

Answer 59

1 - (direct runoff / total precip) * 100 = %

Question 60

Exponential Decay - Horton

Answer 60

purely mathematical, will reach equilibrium; below arch is infiltration and above is runoff

Question 61

Watershed Recovery

Answer 61

hard to predict

Question 62

SCS Meaning

Answer 62

Soil Conservation Service

Question 63

SCS Curve Number

Answer 63

empirical method of estimating excess precipitation; (F/S)=(Q/P)

Question 64

SCS Curve Number Equation

Answer 64

Q = (P - 0.2S)^2 / (P + 0.8S) calculates runoff

Question 65

Q

Answer 65

amount of runoff leaving watershed; units: inches

Question 66

P

Answer 66

precipitation; needs to be greater than Ia to start generating runoff; units: inches

Question 67

S

Answer 67

max amount of water being held; units: inches

Question 68

Ia (Initial abstraction)

Answer 68

accounts for all losses prior to runoff; 0.2S; units: inches

Question 69

precipitation has to exceed this ____ of max storage before generating runoff

Answer 69

20%

Question 70

Estimating S

Answer 70

(1,000 / CN) - 10

Question 71

CN Meaning

Answer 71

curve number

Question 72

CN

Answer 72

runoff for specific land uses; ranges from 1 to 100 (not really); grouped A to D

Question 73

Solar Panels

Answer 73

no equation for figuring out infiltration and runoff for them

Question 74

Saturation

Answer 74

porosity has been reached, max amount of water is being held

Question 75

Water Year Starting Date

Answer 75

October 1st