Responses of groundwater levels to intermittent water transfer in the lower Tarim River

Tarim River is the longest in-land river in China,which controls most of the domain of Xinjiang province,along with the Taklimakan Desert.It has been about 30 years since the river depleted from Daxizi reservoir downstream,which results in lots of serious environmental problems.In the resent years,ecological water conveyances to the lower reaches were performed and tested its effects on solving these problems.Based on the characteristics of hydrogeology and the conditions of climate,a one-dimensional transient groundwater flow model without source and sink is established,and a new method,Fourier transformation,is introduced to solve the equation.In the process,the river table is simplified as steps and the boundary condition of the model is also rendered into a simple form.A section of high density resistivity is conducted to explore the condition of aquifer in the study area for its combining properties of resistivity sounding and electrical profiling.The result of geophysics unveils that the table water aquifer is horizontal and bedded with a thickness of about 35 m.Based on the result,a field data fitting from the simplified model shows that the calculated groundwater table has a very small mean absolute error with a maximum of 0.3 m which is far less than the fluctuation of observed groundwater table.And the correlation analysis unveils a significant correlation between computed and observed values.So the one-dimensional model is good to indicate the changes of groundwater levels in the vicinity of watercourse,and it can be used for evaluating the effects of ecological water conveyance in the lower reaches of the Tarim River.