Impacts of land use changes on groundwater resources in the Heihe River Basin

Land use and land coverchangeshave a greatimpacton the regionalhydrologicalprocess. Based on three periods ofremote sensing data from the 1960s and the long-term observed data of groundwaterfrom the 1980s,theimpactsofland use changeson the groundwatersystem in the middle reach ofHeihe RiverBasin in recentthree decades are analyzed by the perspective ofgroundwater recharge and discharge system. The results indicate that with the different intensities of land use changes, the impacts on the groundwater recharge were 2.602×108 m3/a in the former 15 years (1969-1985) and 0.218 ×108 m3/a in the latter 15 years (1986-2000), and the impacts on the groundwaterdischarge were 2.035×108 m3/a and 4.91×108 m3/a respectively.W hen the groundwater exploitation wasin a reasonable range lessthan 3.0×108 m3/a,the land use changescould controlthe changes of regionalgroundwater resources.Influenced by the land use changes and the large-scale exploitation in the recentdecade,the groundwaterresourcespresentapparently regionaldifferencesin Zhangye region. Realizing the impact of land use changes on groundwater system and the characteristics of spatial-temporal variations of regional groundwater resources would be very importantforreasonably utilizing and managing waterand soilresources.