Transient solution for constant-head pumping at an extended fully penetrating well in confined aquifers

• Main Authors: WEI-HAO JHUANG, 莊惟皓
• Other Authors: Chiu-shia Fen
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/9y4a84

碩士 === 逢甲大學 === 環境工程與科學學系 === 105 === As climate change becomes more and more intensive, dry season is getting drier than before and heavy rainstorms are more often in Taiwan. In the case that surface water is disappeared in dry season and muddy after a rainstorm in wet season, the sublayer of a riverbed may still keep and store water. Water existing and flowing in the layer is called underground stream and is a kind of groundwater. In the past, a lot of different types of pumping well had been developed in order to increase water supply from aquifers. In this study, a new solution of constant-head pumping at an extended fully penetrating well in confined aquifers was developed. This kind of well has a greater radius at the bottom for collecting more water laterally. Separation of variables, Laplace transform and Fourier series were used to solve transient drawdown equations. Darcy's law was then applied to compute wellbore flow rate. Results show that steady state water head distribution and wellbore flow rate obtained with the new solution are consistent with the results from a existing steady state solution. The study further discussed the extending length at the well bottom and soil heterogeneity on affecting the wellbore flow rate. Results show that the radially extending length affects the pumping rate more significantly than the height of the extending. As the ratio of the vertical and horizontal hydraulic conductivity decreases, the time for the wellbore flow rate to reach steady state increases and the differences between the wellbore flow rates derived from a homogeneous and a heterogeneous aquifer increase. Besides, aquifers pumping with this type of well may reach steady state in a day.