In contrast, the 1990's investigations had found that the Red river bed resistance to the Pleistocene aquifer to be about 130 days (Tran Minh, 1984), which is corresponding to the increase of the distance from the river bank further from the well in a thousand of meters to have the river as a specified water level boundary for the aquifer. | Vietnam Journal of Earth Sciences, 40(1), 26-38, Doi: Vietnam Academy of Science and Technology Vietnam Journal of Earth Sciences (VAST) Inverse analysis for transmissivity and the Red river bed's leakage factor for Pleistocene aquifer in Sen Chieu, Hanoi by pumping test under the river water level fluctuation Trieu Duc Huy1, Tong Ngoc Thanh1, Nguyen Van Lam2, Nguyen Van Hoang*3 1 Vietnam National Center for Water Resources Planning and Investigation Hanoi University of Geology and Mining 3 Institute of Geological Sciences, Vietnam Academy of Science and Technology 2 Received 20 April 2017; Received in revised form 26 October 2017; Accepted 15 November 2017 ABSTRACT Aquifer parameters and riverbed hydraulic resistance to an aquifer have an important role in the quantitative assessment of groundwater sources, especially the aquifer recharge from river. The analytical determination of aquifer parameters and riverbed hydraulic resistance to the aquifer is rather complicated in case if the water level in the river fluctuates before and during the pumping test time. This is especially true for Pleistocene aquifer along the Red River in Hanoi city, where the riverbed has been changed very much during the recent decades. A trial-error inverse analysis in the parameters' determination by a group pumping test data obtained with a test located close to the Red river bank in Sen Chieu area, Phuc Tho district, Hanoi city was carried out. Before and during the pumping test time the water level in the river changed five times. The results have shown that the Pleistocene aquifer has a relatively high hydraulic conductivity of m/day, which provides a good role in the transport of a large volume of water recharged by the river to the abstraction wells located near the river. The aquifer storage coefficient had lightly decreased with the pumping time, which is corresponding to the physical nature of that the
