关键词: 水资源平衡, 西北地区, 需水量, 亏水量

Abstract: As land and water resources are out of proportion and the spatial,temp oral distribu,tion of water resources for agriculture is quite uneven in Northwe st China,it is important to study the agricultural water resources balance in th is region.This paper systemically analyzed the agricultural water resources bala nce from two hierarchical aspects and identified the calculation methods for bot h steps.Taking 314 counties as examples,it studied the agricultural water balanc e in Northwest China.Results showed that precipitation can not meet water demand of the crops,hence water deficit is the prime characteristic in water balance i n Northwest China.Deficits of all 12 crops were 898.28mm in Tulufan county,and t he precipitation satisfied ration ranged from 2.74% to 3.71& for different crops .Total water deficits of 12 crops in Xinjiang reached to 628.02 mm,and the preci pitation satisfied ration was only 13.65%.So water deficit was serious in Xinjia ng.The precipitation satisfied ration was 82.37% in Shaanxi province,and the sit uation was the best.Satisfaction ration for different crops were not the same,as for vegetables and rice,since the water demand was much higher than the other c rops,the satisfaction ration was the worst,but the case for potato and hemp was the best.The results showed that even irrigation water was taken into account,it still can not meet the crop water demand in Xinjiang.In the year 2000,the net i rrigation water demand was 141.95×108m3,the water supply can't meet its demand, and the total water deficits were 18.24×108m3.The irrigation water can basicall y meet the water demand in other provinces,water surplus was 9.42×108m3 in Shaa nxi,7.87×108m3 in Gansu,7.38×108m3 in Qinghai,and 23.33×108m3 in Ningxia.Ther e is still certain potential to enlarge irrigated areas in these provinces.

Key words: Northwest China, water balance, water deficit, water requirement