SIMULATING GROUNDWATER DYNAMICS IN AN IRRIGATION-DOMINATED REGION OF NORTH CHINA PLAIN FOR SUSTAINABLE GROUNDWATER MANAGEMENT

North China Plain (NCP) is the most important center of agricultural production and home for more than 200 million people in China. It has been experiencing a rapid depletion of its groundwater resources during last 30 years. Groundwater levels in many places of NCP are currently declining at annual rate of 1 m or even more due to excessive pumping and persistently dry weather. In this study, we developed a numerical model using MODFLOW to simulate the groundwater dynamics in the Shijiazhuang region, a typical area of NCP, where groundwater is the main water supply source for local agriculture irrigation and municipal/industrial water needs. In this model, we divided the Quaternary aquifer in the piedmont plain of Taihang Mountain into two well-connected, shallow and deep aquifer systems. After formulating a set of appropriate boundary conditions, we constructed a steady state model to describe the pre-developed groundwater condition in the 60s. We then simulated the decline of groundwater levels and the development of cones of depression in this region since the 60s to present days. We used 1-D infiltration study results in the deep vadose zone and remote sensing data to improve the accuracy of recharge and ET inputs. The poorly measured irrigation groundwater usage was estimated from the annual grain outputs. Detailed water level measurements and historical water level maps were used to calibrate this model. We then used the calibrated groundwater model to predict the future evolution of groundwater resources in this region under various water usage scenarios. We showed that our model can be a valuable tool for sustainable groundwater management in this region.