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Hydrogeology
N/A
29
Geology
Undergraduate 4
05/12/2014

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Term
Hydrostratigraphy
Definition
Structure of subsurface porous material in reference to the flow of groundwater
Term
Porosity (duel, triple)
Definition
Measure of the empty space in a material (n)
Primary: Matrix
Duel: Fissures
Triple: Conduits/channels
Term
Permeability (primary and secondary)
Definition
Ability of porous material to allow fluids to pass through (k)
Primary: Fluid moving through grains of material
Secondary: Gaps formed later (fissures or channels)
Term
Aquifer thickness (b)
Definition
How thick an aquifer is (b). Because we assume isotropic and homogenous, we try and pick a thickness with the same characteristics. Sometimes that means the thickness is only as thick as one fissure in the bedrock
Term
Hydraulic Conductivity
Definition
Describes how easily water can move through a material (K)
Term
Transmissivity
Definition
How much water can pass horizontally through an aquifer (T=K*b)
Term
Specific Storage
Definition
Amount of water unit volume that can be removed per unit drop in head (Ss)
Term
Storativity
Definition
Amount of water in the aquifer that can be removed per unit drop in head (S=Sds*b)
Term
Infiltration
Definition
Water that gets into the ground
Term
Recharge
Definition
Water that makes it to the water table
Term
Residence Time
Definition
The avg amount of time a substance (chemical) spends in a certain reservoir
Term
Silicate Water Chemistry
Definition
Ca, Mg, Na, SiO2
Less total dissolved solids, silicate minerals weather slowly
More variety of ions
Important buffering system
Term
Carbonate Water Chemistry
Definition
Ca, Mg, HCO3
High total dissolved solids
Carbonate weathers easily
Term
Stable Isotopes
Definition
H2 (deuterium)
O17 and 18
C13
N15
S33, 34, and 36
Term
Unstable Isotopes
Definition
H3
C14
Cl36
Term
Groundwater flow
Steady State Equation
Transient State Equation
Definition
Steady State: d^2h/dx^2+d^2h/dy^2+d^2h/dz^2=0

Transient State: d^2h/dx^2+d^2h/dy^2+d^2h/dz^2=Ss(dh/dt)/k
Term
Theim Equation
Definition
Single well, steady state, hydraulic head can be calculated for any distance from the well if boundary conditions, Q, K, and b are known
h=(Q/2(pi)Kb)ln(r/R)+h-naught

Q is pumping rate
r is radius from pumping well
h-naught is original water level
h is current water level
b is aquifer thickness
K is hydraulic conductivity
R is radius from well that is affected by pumping
Term
Theis Equation
Definition
Transient flow drawdown with multiple wells
s=(Q/4(pi)T)(-0.577-ln(u)+u-u^2/4+u^3/18.....

s is drawdown
Q is pumping rate
T is transmissivity

u=(r^2S)/(4Tt)
S is storativity
Term
Cooper Jacob approximation
Definition
s=(Q/4(pi)T)(-0.577-ln(u)

Simplified. If u is small enough the rest of equation doesn't matter. For u to be small, radius must be small and time must be large
Term
Point Source Pollutants
Definition
Factories, wastewater treatment plants, abandoned mines, landfills, Storage Tanks
Term
Non-point Source Pollutants
Definition
Agriculture, Lawns/Gardens, Street refuse, Construction
Term
Gamma Log
Definition
Shows what type of rock the aquifer is located in
Term
Caliper Log
Definition
Borehole diameter
Term
Fluid resistivity/conductivity and fluid temp log
Definition
Measures total dissolved solids (how conductive water is) and the temperature of the water
Term
Flowmeter Log
Definition
How the water is flowing in the well
Slight slope indicates some flow
Flat line indicates fissure of some sort with lots of flow
Term
No flow boundary
Definition
Constant rate of recharge straight down
Term
Constant head boundary
Definition
River
Term
Constant flux boundary
Definition
Well pumping at a steady rate
Steady state of recharge
Term
Finite difference approx for hydraulic head
Definition
Hydraulic head=Average of the four surrounding nodes (think excel for numeric modeling)
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