Question

Problem 24 A well is screened in a completely confined aquifer is to be pumped at a rate of 165,000 ft/d for 30 days. If the aquifer transmissivity is 5320 ft/d and the storativity is 0.0007, what is the drawdown at 50, 150, 250, 500, 1000, 3000, 5000, and 10,000 ft Problem 25 If the aquifer in problem 24 is not completely confined, but overlain by a 8.0 ft leaky confining layer with a vertical hydraulic conductivity of 0.024 ft/d and no storativity, what would be the drawdown at the given distances and with the given pumping rate? Problem 26 Graph the change in head for the wells in problem 24 and 25 Problem 27-28 With reference to the well and aquifer system described in problem 25, compute the drawdown at a distance of 100 ft from the well at the following times: 1, 2, 5, 10, 15, 30, and 60 minutes; 2, 5, and 12 hours, and 1, 5, 10, 20 and 30 days. Use Microsoft Excel. Submit your excel files with work and the answers CLEARLY labeled. Well Function equations For the W(u), use the following equation to determine the W(u) value. Wu)- -0.975Infu)+0.9111 R2 0.9988 For the leaky well function (W(u, r/B) use: W(u, r/8) -3.5091e 167 if r/B 0.09 For the Besel function (K0): The Bessel function can be found in excel like this"- BESSELK(NUM, O) Where the NUM r/B

Answer 1

Convert Q trom gal/min to ft'/day h-29.34ft r 26ft 1ft1440 min 0-1 220 h,-32.56 ft -17.48 galt 1day r-73 ft 42,400 73 42400よ. 2x(32.56 ft-29.34 ft) 126 2164 tt/day T-Kb-2164K[78 ft]->K-27.7 f/day Steadystate (equiibrium) pumping in an unconfined oquifer (Example of model simulation) No Pumping Condition Cross-section

With pumping at the center of the aqulfer Il Cross-section Non-equilibrium pumping (or transient) Drawdown (s) is o function af time ond distance Canfined oqulfer Use Theis solution . .Aquifer is homogeneous isotropic, and is of infinite extent we" completely penetrates (and get water from) the entire aquifer Transmissivity is constant Water is removed from storage and discharge instantaneously. ·

Theis Solution 4AT r's wu)-l-dr»-0.5772-Inu + u--+--… where and u=-, 2.21 3 3 s drawdown ] nitial head in a well at distance h head at distance r at time t[ tme since pumping begins IT] r distance from pumping well L a pumping rate L'm transmissivity [' storativity b aquifer's saturated thickness [LI Mu) well function -1 u auxillary parameter -
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