Laserfiche WebLink
<br />, . <br /> <br />DENVER BASIN GROUND WATER MODEL REPORT <br /> <br />Subsequent to the passage of Senate Bill 5 the State Engineer's Office <br />undertook the task of defining, within each of the Denver Basin aquifers, <br />areas of nontributary ground water. Senate Bill 5 provides that a <br />determin~tion be made by the State Engineer if the ratio of rate of stream <br />depletion (q) to the pumping rate (Q) of a proposed well is less than 0.1%. <br />A determination of q/Q less than 0.1%, when the q used is that after 100 <br />years of pumping, defines a nontributary well. <br /> <br />USGS 3-DIMENSIONAL.GROUND WATER MODEL <br /> <br />The State Engineer's Office chose the "Modular Three-Dimensional <br />Finite-Difference Ground Water Flow Model" (1) to compute the stream <br />depletion (q) for various well locations to determine areas of nontributary <br />ground water. <br /> <br />General Equation <br /> <br />Assuming constant temperature, viscosity and density the' general <br />equation for 2-dimensiona1 ground water flow is: <br /> <br />, ~) <br />. . > <br />I.._~ .~. . <br /> <br />a [ ah] <br />ax T(x,y,~) ax <br /> <br />il r: ( Clh] Clh <br />+ ily L"T x,y, t) ily = S(x,y)-at + W(x,y, t), <br /> <br />where <br /> <br />Eq (1) <br /> <br />x, yare space coordinates <br />T (x,y,t) is the transmissivity (L2r-1) <br />h is the hydraulic head (L) ~~ <br />W (x,y,t) is the volumetric flux per unit ~ (LT-1) and can <br />be used to represent pumping, flows to or from streams and <br />vertical leakage between aquifers . <br />S (x,y) is the specific yield of the porous material (dimensionless) <br />t is time <br /> <br />Equation (1) is the general ground water flow equation, which constitutes a <br />mathematical model of ground water flow when boundary conditions and initial <br />hydraulic heads are specified. <br /> <br />Equation Solution' <br /> <br />An analytic solution to equation (1) is unobtainable in all but the <br /> <br />r....),:. ,\ <br />""'-'.j <br />