Groundwater Flow Field Evolutoin Characteristic And Size Effect Of Shijiazhuang Plain

Shijiazhuang plain is the wheat major and high production region in china,the most serious groundwater over-exploit area of North China Plain,and the most intense regions for the impact of climate change and human activities.Since encountered extraordinary drought in1972,groundwater exploit increase continuously,and the over-exploit amount has got to18billion cubic metre. the groundwater level has declined from10～15m in1960s to25～50m in present day. groundwater flow field has changed from natural state to two element circulation mode. longitudinal flow movement slowing down, vertical water flux exchange unceasing enhancement. the flow direction of groundwater has been by the natural state of moving from west to east, into the status from surrounding to depression cone,has grave affected water security and economic,social sustainable development.So launch the study of groundwater flow field evolution charateristic and size effcet of Shijiazhuang plain"has important significance for groundwater rational utilization and conservation of Shijiazhuang plain.Using the data of meteorological,groundwater exploition,ground water level,output data of the GCM(2011-2060),further study the groundwater flow field evolution characteristic and size effcet of Shijiazhuang plain,the relationship and machanism between groundwater flow field evolution and climate change,human activities.construct climate scenairos of Shijiazhuang plain,and predict the tendency of groundwater level variation in2011-2060, with the methods of wavelet transform,and water resouce balance.The main advance and innovation results as follows:(1) As human activities influence strength increasing,the groundwater flow field evolution of Shijiazhuang plain can divide into four stage.In the period of groundwater beginning over-exploit,groundwater level decline rates is0.38m/a.In the period of groundwater depression cone development, groundwater level decline rates is0.69m/a.During the serious over-exploit stage, groundwater level decline rates is1.03m/a.During the period of exploitation control, groundwater level decline rates is0.74m/a.(2) The evolution of groundwater flow field in Shijiazhuang plain exist size effect.In one year size, the stage of groundwater flow field evolution is not obviously.In four,five,and more year size, the stage of groundwater flow field evolution is generalized.In two or three year size, the stage of groundwater flow field evolution can be clearly displayed.(3) Through the methods of driving factors discrimination of Shijiazhuang groundwater flow field evloution.We can get the exploitation influnce strength on groundwater flow field is43.45%,before1980.In the stage of grave over-exploitation,the influnce strength of exploitation is55.1%.In the stage of control exploitation, the influnce strength of exploitation is53.47%.Precipitation variation has obvious effect on groundwater flow field. Since1972, low precipitation frequently happened in Shijiangzhuang plain, and the influence strength of precipitation in initial over-exploitation stage is19.19%.In the stage of groundwater depression cone developed, precipitation influence strength is20.62%. In the stage of gravely over-exploitation, precipitation influence strength is21.19%. In the stage of control exploitation, influence strength of precipitation is24.30%.(4)Through the methods of SDSM and water balance principle, predicting groundwater flow field development tendency of Shijiazhuang plain in the current climate conditions and RCP4.5climate scenarios.The results as follws:In current climate conditions, groundwater level in the next50years will decline1.74m,0.79m and0.41m respectively in300mm,240mm and210mm three kinds of irrigation quota.In RCP4.5climate scenarios, groundwater levev in the next50years will decline1.48m,0.67m and0.33m respectively in300mm,240mm and210mm three kinds of irrigation quota.