1. Stream Depletion Rate with Horizontal or Slanted wells in Confined Aquifers near a Stream 授課老師 : 陳文福 指導老師 : 馮正一 報告人 : 鄒佩蓉 1 探討水平井或傾斜井於河邊受壓含水層抽水之河川損耗率 (SDR) 國立中興大學水土保持學系碩士班 專題討論 ( 二 ) 99.06.04

2. 2 IntroductionMethod Results and Discussion Conclusion -Outline-

3. 3IntroductionMethod Results and Discussion Conclusion 1.Typhoon, Matsa( 馬莎颱風 ) (2005/08/05) Water deficient problem 2.The water company solved the water deficient problem by pumping groundwater near the Taoyuan canal. 3. Linsley and Franzini(1979), the groundwater is usually cleared of sediments if flowing through fine-grained materials within a distance of 30 m.

4. 4 1.Vertical well (e.g., Hunt, 1999; Zlotnik and Huang, 1999; Bulter et al., 2001; Fox et al., 2002; Chen and Yin, 2004; Sun and Zhan, 2007; Bulter et al., 2007; Yeh et al., 2008; Zlotnik and Tartakovsky, 2008) Stream Depletion Rate (SDR) Stream Depletion Rate (SDR) Water deficient problem IntroductionMethod Results and Discussion Conclusion Large drawdown 2. Streambed Pumping groundwater near a stream

5. 5 Water deficient problem Pumping groundwater near a stream Stream Depletion Rate (SDR) Stream Depletion Rate (SDR) Large drawdown Horizontal well 1. Some locations such as buildings, roads, etc. 2. Thin aquifer 4. Operating costs reduction (Joshi, 2003)IntroductionMethod Results and Discussion Conclusion 3. Better contact within the stratum

6. 6 Water deficient problem Pumping groundwater near a stream Stream Depletion Rate (SDR) Stream Depletion Rate (SDR)IntroductionMethod Results and Discussion Conclusion 1. Zhan et al. (2001) provided an analytical solution to describe flow toward a horizontal well in an anisotropic confined aquifer. 2. Zhan and Zlotnik (2002) extended point source solution to the cases of slanted wells based on the principle of superposition. 3. Sun and Zhan (2006) mentioned the use of a horizontal well in an aquitard-aquifer system beneath a water reservoir for water supply. Large drawdown Horizontal well

7. 7 Conceptual Model IntroductionMethod Results and Discussion Conclusion

8. 8 Boundary & Initial Conditions datumIntroductionMethod Results and Discussion Conclusion

9. 9 B.C.B.C. I.C.I.C. Fourier sine transform Fourier transform Finite Fourier cosine transform First-order ordinary differential equation Mathematic IntroductionMethod Results and Discussion Conclusion

10. 10 Applying inverse Fourier transforms and the principle of superposition The head solution IntroductionMethod Results and Discussion Conclusion point source solution

11. 11 Applying Darcy’s Law SDR IntroductionMethod Results and Discussion Conclusion

12. 12 Effects of well distance on SDR IntroductionMethod Results and Discussion Conclusion

13. 13IntroductionMethod Results and Discussion Conclusion Effects of well direction and length on SDR

14. 14 β = 90°, vertical well α = 90°, well parallel to the streamIntroductionMethod Results and Discussion Conclusion Best α and β for less time for reaching quasi-steady state

15. 15 Effect of anisotropic aquifer IntroductionMethod Results and Discussion Conclusion

16. 16 1. various depth of the horizontal well 2. various length of the horizontal wellIntroductionMethod Results and Discussion Conclusion Drawdown of horizontal and vertical wells

17. 17IntroductionMethod Results and Discussion Conclusion 1. The SDR is almost independent of the length of the horizontal well. The SDR reaches quasi-steady state more quickly if the well is closer to the stream. 2. To avoid producing large drawdown and have less time for reaching quasi-steady SDR, the horizontal well would be better to install parallel to the stream. 3. The K x plays the key role in effecting the time for reaching quasi-steady SDR while K y has no influence on the time for reaching quasi-steady SDR. 4. The use of a long horizontal well in producing small drawdown is better than that of a deep one under a constant pumping rate.

18. 18 END Thanks for your attention!