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一、西部地区水资源概况及利用现状与问题 (一)水资源分布及主要特征 西部地区江河水系分属黄河上中游、西南诸河、长江上游、内陆河四大流域片。长江与西南诸河流域多年平均径流深都在500毫米以上,黄河只有100毫米,内陆河流域更小,而且其平原区又是我国降水最少的地区。可见,水资源地区分布不均,形成西南地区水多,西北地区水少的格局。水资源在时间上分布也不均匀,我国降水量与径流量的年际变化西北地区最大,西南地区最小,年际变化大造成连续丰枯水年的出现。而年内变化在各个地区普遍存在。
I. General Situation and Problems of Water Resources in the Western Region and Current Status and Problems (I) Distribution and Main Characteristics of Water Resources The river system in the western region is divided into four major river basins: the upper and middle reaches of the Yellow River, the rivers in the southwest, the upper reaches of the Yangtze River, and the inland rivers. The average annual runoff depths of the Yangtze River and the southwestern river basins are all above 500 mm, the Yellow River is only 100 mm, and the inland river basin is smaller, and its plain area is the least precipitation area in China. It can be seen that the distribution of water resources is uneven, forming a pattern of water in the southwest and less water in the northwest. The distribution of water resources in time is also uneven. The interannual variation of precipitation and runoff in China is the largest in the northwest, and the smallest in the southwest, with large interannual variations leading to the emergence of continuous flood seasons. Changes during the year are widespread in all regions.