长江流域水资源评价

Assessment on water resources of Yangtze River

水资源调查评价是水资源综合规划的基础。通过对长江流域水资源（1956—2000年系列）的调查评价，可系统地提供地表、地下水资源数量及时空分布的特点和演变趋势，准确地评价长江流域水资源条件和特点。长江流域水资源丰富，平均水资源总量为9958亿m^3，约占全国水资源总量的35％，但时空分布不均。受降水量地区分布差异影响，长江中游地区水资源总量多于上游和下游地区。长江流域近21a（1980—2000年）平均降雨量较前24a增多，水资源总量有所增加，下游地区增加幅度较大。

Water resources investigation and evaluation is the basis for comprehensive planning of water resources. Through the investigation and evaluation of water resources in the Yangtze River Basin （ 1956 -2000）, the quantity of surface and groundwater resources, the characteristics and the evolution trend of temporal and spatial distribution are provided systematically. Meanwhile, the condition and characteristics of the water resources of Yangtze River Basin can be evaluated accurately. Due to the rich water resources of Yangtze River Basin, the average total water resources is 995.8 billion m3 with the uneven spatial and temporal distribution, accounting for 35% of the total water resources of China. Affected by differences in regional distribution of precipitation, the total water resources in the middle Yangtze River area is more than those in the upstream and downstream areas. The average rainfall in the Yangtze River Basin in the recent 21 years （1980 - 2000） is more than the previous 24 years, and the total water resources increase, especially for the downstream.