郭守敬
Historically, since the Yuan dynasty Beijing received its water mainly through canals from springs in the mountains north and west of the city, feeding a system of lakes designed by Guo Shoujing. This allowed the city to thrive although it was located far from a major river. However, the yield of these springs declined as a result of deforestation and the springs do not supply Beijing with water any more. They were replaced by groundwater and by reservoirs from dams built during the 1950s in the areas surrounding Beijing as the major sources of water supply for the city.