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“del operator”. Gradient :. Divergence :. Laplacian :. Diffusion Equation :. “del operator”. Gradient :. Divergence :. Laplacian :. Diffusion Equation :. “Diffusion Equation”. Cartesian Coordinates. Cylindrical Coordinates. Cylindrical Coordinates, Radial Symmetry ∂h/∂ f = 0.
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“del operator” Gradient: Divergence: Laplacian: Diffusion Equation:
“del operator” Gradient: Divergence: Laplacian: Diffusion Equation:
“Diffusion Equation” Cartesian Coordinates Cylindrical Coordinates Cylindrical Coordinates, Radial Symmetry ∂h/∂f = 0 Cylindrical Coordinates, Purely Radial Flow ∂h/∂f = 0 ∂h/∂z = 0
Flow beneath Dam Vertical x-section Flow toward Pumping Well, next to river = line source = constant head boundary Plan view River Channel Domenico & Schwartz (1990)
Well Drawdown Case 1: Confined aquifier, Constant pumping rate Q, Steady radial flow where m=aquifer thickness “Equilibrium” eq., or “Theim” equation e.g., Fetter eq 7-38 D&S eq. 5.21 2x = Drawdown
m Potentiometric Surface Q Confined Aquifer
Well Drawdown Case 2: Unconfined aquifier, Constant pumping rate Q, Steady radial flow where m=aquifer thickness Unconfined “Theim” equation e.g., Fetter eq 7-39 D&S eq. 5.24 ≠ (Drawdown)2
Swindle: 1) Singulatity at r = 0 2) Steady state flux impossible without source - this problem requires annular source term 3) Purely radial flow impossible for unconfined case
Radial flow Transient flow, Confined Aquifer, No recharge Constant pumping rate Q Initial Condition & Boundary conditions:
Radial flow Initial Condition & Boundary conditions: Solution: “Theis equation” or “Non-equilibrium Eq.” where and where
Approximation for t >> 0 D&S p. 151
Pumping of Confined Aquifer Not GW “level” Potetiometric sfc! USGS Circ 1186
Pumping of Unconfined Aquifer USGS Circ 1186
FLOW NETS Impermeble Boundary Constant Head Boundary Water Table Boundary after Freeze & Cherry
Santa Cruz River near Tucson AZ 1942 USGS Circ 1186
Santa Cruz River near Tucson AZ 1989 >100’ GW drop USGS Circ 1186
Santa Cruz River Martinez Hill, South of Tucson AZ 1942 Cottonwoods, Mesquite 1989 >100’ GW drop USGS Circ 1186
Initial Condition Pumping @ rate Q1 (note divide) Pumping @ rate Q2 >Q1 USGS Circ 1186