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intro to hydro
midterm
36
Geology
Undergraduate 4
10/21/2013

Additional Geology Flashcards


 

 


 

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Term
Groundwater
Definition
water found in the pores of soil, sediment, and rocks, plus narrow fractures in bedrock
Term
Hyrdogeology
Definition
the occurence, distriubtion, movement, quality, quantity, and interaction of water in earth's crust.
Term
belt of soil moisture
Definition
water held by molecular attraction on soil particles in the near surface zone
Term
zone of saturation (vadose zone)
Definition
formation- water not held as soil moisture percolates downwawrd.

water reaches a zone where all the open spaceds in sediment are completely filled with water
Term
Phreatic zone
Definition
Totally saturated with water, water moves
Term
low pressure water table rises
Definition
high pressure water table falls
Term
unsaturated zone
Definition
area above water table
include capillary fringe belt (saturated but doesnt flow bc GW is held by surface tension in tiny passages btwn grains
Term
Effluent/ Gaining streams
Definition
gain water from inflow of GW through the streambed
Term
Influent/ Losing stream
Definition
lose water to GW system bc of outflow through streambed (recharge spot)
Term
connected & disconnected/ Combo
Definition
stream gains in some sections and loses in others
Term
porosity
Definition
the percent of total volume of rock or sediment that consists of open pore spaces

determines how much GW can be stored
Term
permeability
Definition
ability of a material to transmit fluid
Term
aquitard
Definition
an impermeable layer that hinders or prevents water movement (clay)
Term
aquifer
Definition
permeable rock strata or sediment that transmits GW freely (sand and gravels)
Term
movement of groundwater
Definition
super slow, typically few cm a day
energy for movement is provided by gravity
Term
DARCY'S LAW
Definition
if permeability remains uniform, the velocity of GW will increase as the slope of the water table increases

^ slope then ^ velocity
Term
HYDRAULIC GRADIENT
Definition
the water table slope, determined by dividing the vertical distance between recharge and discharge (change in heads) by the length of flow between them
Term
HYRDAULIC HEAD
Definition
the vertical difference between the recharge and discharge points
Term
recharge
Definition
infiltration- rain/snow
losing streams
irrigation (manmade)
septic systems (manmade)
lake
wetlands (swamps)
Term
discharge
Definition
streams
springs (w/perched aquifers)
lakes
wetlands/ swamps
wells (manmade)
Term
potentiometric surface
Definition
pressure, level water wants to rise to in a well
Term
springs
Definition
natural outflow of GW
occur where WT meets earth's surface
can be cause by an aquitard creating a localized zone of saturation (perched water table)
Term
hotsprings
Definition
water is warmer than mean annual air temp
the water is heated by the cooling of igneous rock (no pressure involved)
Term
geyser
Definition
water erupts w/great force

occurs where extensive underground chambers exist within hot igneous rock

GW heats, expands, changes to steam, erupts
Term
pumping of wells
Definition
drawdown-lowering of WT
cone of depression in WT
Term
artesian well
Definition
situation in which gw under pressure rises above the level of an confined aquifer
Term
subsidence
Definition
the ground sinks when water is pumped from wells faster than natural recharge replaces it
Term
cave features
Definition
dripstone (travertines)
calcite deposites (evaporites)
collectively called spelothems (includes stalactites-from ceiling and stalagmites-from floor)
Term
karst topography
Definition
landscapes that have been shaped mainly by the dissolving power of GW

sinkholes-formed by GW slowly dissolving the bedrock forming a collapse
Term
importante of GW
Definition
as an erosional agent, dissolving GW produces sinkholes, caverns

GW serves as an eqalizer of streamflow
Term
CONCEPT OF DARCY'S LAW
hyrdaulic properties
Definition
Aquifer functions
conduit function-flow through it
storage function- store water

Flow properties (conduit function)
Hydraulic conductivity (K)- basically permeability, has to be able to flow through earth materials
Transmitivity

Storage characterisitcs (storage func)
porosity
specific yield (how much is it going to give up)
specific storage
storativity (storage coeff.)
Term
hydraulic conductivity is a function of
Definition
PHYSICAL PROP. OF POROUS MATERIALS
grain size
shape of grains
arrangement/sorting
PROP OF THE MIGRATING FLUID
viscosity
density
specific weight all controlled by temp.
Term
Transmitivity (T)
Definition
amount of water that can be transmitted thru a unit width by the full saturated thickness of the aquifer
T=bk
Term
Storativity of storage coeff. (S)
Definition
dimensionless # that represents the water that a formation releases or absorbs from storage per unit surface area per unit change in head (=Sy w/unconfined aquifer)
S=V of water/AH
Term
Specific Storage
Definition
the amount of water that a portion of an aquifer releases from storage, per unit mass or volume of aquifer, per unit change in hydraulic head, while remaining fully saturated.

When you release pressure mineral grains expand and water volume expands and moves out b/c less pore space
Term
Homogeneity + Isotropy Looking @ K values
Definition
Homogenous- K indep. of location
Heterogenou- K dep. on location
Isotropic- K indep. on direction (round grains)
Anisotropic- K varies w/direction (flat grains)
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