Groundwater discharge downstream of an arid inland river in Northwestern China

Nalenggele River is an inland river located in the arid, fragile ecological environment area in Northwestern China. Groundwater discharge to the river can significantly impact the ecologic environment in the Nalenggele River basin, but few hydrogeological studies have been conducted in the inland arid basin. In this paper, two sections were chosen to analyze the groundwater discharge in the downstream of Nalenggele River. Section I–I′ is located in the west of the downstream of this river, while section II–II′ is in the east. Two methods were used to calculate the discharge in section I–I′: Darcy's law and Modflow simulation. In these two methods, the vertical hydraulic conductivity of the stream sediment is a key parameter, which was determined by a falling-head permeameter test in the river. The results show that the groundwater discharges by the above two methods are very close to the results of a previous study by the ²²²Rn mass balance method. This is the first attempt to use a field test method to obtain the vertical hydraulic conductivity and the hydraulic gradient, and to illustrate the groundwater discharge in the downstream of Nalenggele River in Northwestern China by classic methods.