groundwater Flashcards
(50 cards)
Hydrologic horizons in order
root zone
intermediate zone
capillary fringe
water table
groundwater zone
impermeable layer
2 main zone of hydrologic soil horizons
Vadose (unsaturated) = water fills some pores
Phreatic (saturated) = water fills all pores
Capillary fringe
Belt of variable thickness presenting wet envr in saturated zone due to capillary rise
Process affecting water in subsurface
Infilitration
percolation
recharge
capillary rise
interflow/ subsurface flow
GW flow
Infiltration
movement of water from soil surface downwards
Percolation
downward movement of water in unsaturated zone
recharge
addition of water to saturated zone
capillary rise
movement of water from saturated zone upwards into unsaturated zone
Interflow/ subsurface flow
flow occuring in unsaturated zone in lateral direction
GW flow
flow in saturated zone
Soil texture
describes grain size distribution for particles below 2mm -> influence infilitration, runoff, etc.
total porosity (n) equation
n = V voids/ V total
Void ratio (e)
V voids/ V solids
soil water content volumetric
V water / V total
soil water content gravimetric
(Mass wet - mass dry )/ mass dry
Relating gravimetric to volumetric
(Bulk density soil/ bulk density water) x mass
Degree of Saturation (S)
S = V water / (V water + V gas)
soil water storage type
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
Soil moisture critical values
Field capacity
permanent wilting point
plant available water
Field capacity
max amount of water soil holds after gravitation drainage
PWP
Minimum soil moisture content after gravity drainage AND plant evapotranspi
Plant available water
difference between FC and PWP
hydro horizon and critical moisture value:
root: PWP < moisture < n
intermediate: FC < moisture < n
capillary : moisture = n
saturated: moisture = n
Water migration caused by
water pressure difference:
-from higher to lower pressure