STUDY ON SOIL WATER RESOURCES IN RAIN-FED AGRICULTURAL REGION OF GANSU PROVINCE

Based on the soil moisture data of eleven stations and related meteorological data in rain-fed agricultural region of Gansu province, the spatial-temporal law of soil moisture variation and the replenishment of precipitation and the conditions of soil water are analyzed. The soil moisture decreases from southeast to northwest whereas the variation coefficient increases in the region. The variation of soil moisture mainly occurs above 90 cm depth in the region where soil moisture is insufficient and 180 cm depth or so in other three regions. The regional variation of the replenishment ratio of precipitation is about 15.3%~41.7%. In addition to the impact of precipitation on replenishment ratio, the soil type is also an important restrictive factor to replenishment. The water deficit exceeds 100 mm during wheat growing season in all stations except Chengxian, Lingxia and Xifeng, and the ratio of water deficit to wheat water requirement is about 30%~50%.