The response of hydrological process of Liulin karst spring to both climate and anthropogenic activities in different stages

The Liulin karst spring flow has been declining since 1950s, and the main cause to the attenuation is more and more intensive human activities and instructions. By using the Grey system model piecewise, this paper focuses on analyzing the effects of anthropogenic activities to hydrological process of Liulin karst spring statistically. In the first stage (1957-1973), Liulin Springs flow is only affected by climate; in the second stages (1974-1996), Liulin Spring flow is affected by climate and human activities, and not steady; in the third stage (1997-2009), Liulin Springs flow is affected by climate and human activities, and steady. Then through scientifically comparing, we analyzed the effect of human activities to hydrological process of Liulin Spring by using Grey relational analysis and GM model with time lags. The results illustrate that (1) the lag increases from 0 to 4 years; (2) the most important recharge to karst flow is precipitation (3) it is human activities that caused the attenuation of spring flow after 1974, which means that human activities have significantly negative influences on the supplement of precipitation to Liulin Spring.