In the Qin and Han Dynasties (221 BC~220 AC) people dug artesian wells to a depth of 10~200 m (Hydrology and Geology Research Group in Shanghai, 1977). The Karez was invented during this period and used to intercept groundwater for agriculture irrigation and residential water consumption. A Karez is generally made up of a shaft, an under drain, an open channel and a water-logging dam (Figs. 1 and 2). The Karez guaranteed a stable irrigation water support and a low evaporation of groundwater, which was scarcely affected by surface temperature.