groundwater

Question 1

Hydrologic horizons in order

Answer 1

root zone
intermediate zone
capillary fringe
water table
groundwater zone
impermeable layer

Question 2

2 main zone of hydrologic soil horizons

Answer 2

Vadose (unsaturated) = water fills some pores
Phreatic (saturated) = water fills all pores

Question 3

Capillary fringe

Answer 3

Belt of variable thickness presenting wet envr in saturated zone due to capillary rise

Question 4

Process affecting water in subsurface

Answer 4

Infilitration
percolation
recharge
capillary rise
interflow/ subsurface flow
GW flow

Question 5

Infiltration

Answer 5

movement of water from soil surface downwards

Question 6

Percolation

Answer 6

downward movement of water in unsaturated zone

Question 7

recharge

Answer 7

addition of water to saturated zone

Question 8

capillary rise

Answer 8

movement of water from saturated zone upwards into unsaturated zone

Question 9

Interflow/ subsurface flow

Answer 9

flow occuring in unsaturated zone in lateral direction

Question 10

GW flow

Answer 10

flow in saturated zone

Question 11

Soil texture

Answer 11

describes grain size distribution for particles below 2mm -> influence infilitration, runoff, etc.

Question 12

total porosity (n) equation

Answer 12

n = V voids/ V total

Question 13

Void ratio (e)

Answer 13

V voids/ V solids

Question 14

soil water content volumetric

Answer 14

V water / V total

Question 15

soil water content gravimetric

Answer 15

(Mass wet - mass dry )/ mass dry

Question 16

Relating gravimetric to volumetric

Answer 16

(Bulk density soil/ bulk density water) x mass

Question 17

Degree of Saturation (S)

Answer 17

S = V water / (V water + V gas)

Question 18

soil water storage type

Answer 18

Gravitational: excess drained under gravity at saturation
Capillary: held in soil pore in intermediate/wet conditions
Hygroscopic: thin films holding onto soil grains in dry conditions

Question 19

Soil moisture critical values

Answer 19

Field capacity
permanent wilting point
plant available water

Question 20

Field capacity

Answer 20

max amount of water soil holds after gravitation drainage

Question 21

PWP

Answer 21

Minimum soil moisture content after gravity drainage AND plant evapotranspi

Question 22

Plant available water

Answer 22

difference between FC and PWP

Question 23

hydro horizon and critical moisture value:

Answer 23

root: PWP < moisture < n
intermediate: FC < moisture < n
capillary : moisture = n
saturated: moisture = n

Question 24

Water migration caused by

Answer 24

water pressure difference:
-from higher to lower pressure

Question 25

hydro horizon and water pressure

Answer 25

unsaturated soil: negative P saturated : positive P water table: P = 0

Question 26

water table

Answer 26

fluctuates up and down with precipi usually parallel to soil surface

Question 27

measuring soil water tension

Answer 27

Tensiometer -> tube partially filled with water with low-permeability porous cup at bottom that balance with soil pressure

Question 28

Hydraulic conductivity (K)

Answer 28

ease at which water can move through pore spaces/ soil fractures -larger for sand VS smaller for clay

Question 29

Rainfall rate (i)

Answer 29

rainfall intensity = amount per time

Question 30

infiltration capacity (fc)

Answer 30

max rate soil can absorb water through surface

Question 31

infiltration fate f(t)

Answer 31

time-variable rate of water entering soil via surface

Question 32

how does f(t) vary throughout rainfall event

Answer 32

at first, decrease rapidly then plateau near fc

Question 33

Wetting front

Answer 33

sharp discontinuity in soil profile with dry below and wet above -> created by change of soil moisture with depth due to top-down infiltration BUT not always at constant depth -> preferential flow

Question 34

Cumulative infiltration F(t)

Answer 34

accumulated depth of infiltration from beginning of rainfall to given time -> area under curve of f(t)

Question 35

Time of ponding H(t)

Answer 35

time a which surface layer is saturated with rainfall rate exceeding hydraulic conductivity 2 conditions: fully saturated soil OR higher rainfall rate than infiltration rate

Question 36

Horton & Philip models

Answer 36

Both measure f(t) , F(t) and H(t) Horton -> include f0 and fc Philip -> use suction and K

Question 37

what controls infiltration

Answer 37

soil surface condition subsurface conditions influencing factors flow influence hydrophobicity

Question 38

Subsurface conditiond

Answer 38

soil characteristics (porosity, depth, etc.) root system water table depth subsurface drainage hydraulic conductivity

Question 39

soil surface conditions

Answer 39

land use vegetation cover roughness and slope cracking/ crusting surface sealing

Question 40

factor influencing surface/ subsurface conditions

Answer 40

mechanical process freeze-thaw cycle litter layer compaction antecedent soil water conditions chem activity bio activtiy microbial activity

Question 41

hydrophobicity

Answer 41

dryness heat plant chem aromatic oils fire other chem

Question 42

Flow influence

Answer 42

ponding soil and water temperature

Question 43

Saturated flow

Answer 43

movement of water via saturated pores & fractures -relatively slow BUT higher in limestone

Question 44

Flow velocity depends on:

Answer 44

slope of water table permeability of rock/ sediment of aquifer

Question 45

aquifer

Answer 45

saturated, permeable, geologic unit transmitting significant amount of GW under ordinary gradient

Question 46

aquiclude

Answer 46

saturated, geologic unit doesnt transmit significant amount of GW under ordinary gradient

Question 47

Aquifer types

Answer 47

unconfined confined perched

Question 48

unconfined aquifer

Answer 48

aquifer with lower barrier bc of aquiclude below BUT not upper barrier -> water fluctuates upwards -partially filled and rapidly recharged

Question 49

confined aquifer

Answer 49

aquifer with lower and higher barrier bc aquiclude above and below -completely filled and slow to recharge

Question 50

perched aquifer

Answer 50

unconfined water zone sitting on top of clay and separated from main aquifer below