Responses of the sustainable yield of groundwater to annual rainfall and pumping patterns in the Baotou Plain

摘要

Serious water deficits are threatening the sustainable socio-economic development and the protection of the ecology and the environment in North China, especially in Baotou City. There is a common misconception that groundwater extraction can be sustainable if the pumping rate does not exceed the total natural recharge in a groundwater basin. The truth is that the natural recharge is mainly affected by the rainfall and that groundwater withdrawal determines the sustainable yield of the aquifer flow system. A new sustainable yield method introduced in this paper is a useful baseline for groundwater management under all rainfall conditions and given pumping scenarios. The dynamic alternative to the groundwater sustainable yield for a given pumping pattern and rate would consider the responses of the recharge and discharge to the groundwater level fluctuation, then predict the groundwater head at the end of this period to determine the control storage, and then determine the sustainable yield for the shallow and deep aquifer. The simulation results show that the dynamic sustainable yield for a shallow aquifer ranges from 70 to 143 million m(3), and the yield for a deep aquifer varies from 54 to 77 million m3; the average yield is 95.61 million m(3) for the shallow aquifer and 38.03 million cubic meter for the deep aquifer. The results of this study indicate that the multi-year sustainable yield only accounts for about one-half of the average annual recharge. These actions show that sufficient rainfall supports excessive pumping patterns, causing a slow and disproportionate groundwater storage recovery and water level rise. In addition, the decrease in the recharge and the increase in the discharge were found to have a notable effect on the dynamic annual sustainable yield, especially in a drought year.