大渡河上游干旱河谷区生态需水研究

为了预测南水北调西线一期工程实施对下游干旱河谷演变的影响,开展了对泸定县城以上大渡河流域干旱河谷区生态需水的研究,结果表明:①干旱河谷生态需水量为能够维系干旱河谷生态功能的基本环境目标、恢复干旱河谷生态景观的生态系统所需求的水量;②研究区干旱河谷总面积1185.00km₂,其中干暖河谷250.11km₂,干温河谷934.89km₂;③考虑输沙需水时,维持研究区干旱河谷的最小生态需水量为156.3×108m3,其中干暖河谷最小为58.8×108m3,干温河谷最小为97.4×108m3,不考虑输沙需水时,最小生态需水量仅为58.3×108m3;④河道外需水量占总生态需水量的5.7%;⑤考虑输沙需水时,研究区干旱河谷的最小生态需水量占总地表水量的68.84%,不考虑输沙需水时其只占总地表水量的25.68%,对生态脆弱区生态需水进行计算时需考虑输沙需水。

Study on Ecological Water Requirement of Dry Valleys in the Upper Reaches of the Dadu River

In order to predict the impact of first phase of west route water transfer from south to north project on the evolution of the dry valleys downstream,we carried out studies on the ecological water requirement of the dry valleys in the upper reaches of the Dadu river and found that:1)Ecological water requirement of the dry valleys depends on the demand of water for maintaining ecological function and for restoring ecosystem;2)the area of the dry valleys(including woods,shrubs,nudity etc.)estimated using ARC GIS and ERDAS softwares is 1185.00 km2,of which the dry,warm valley is 250.11km2,and dry,mild valley is 934.89km2;3)considering water requirement for sediment transportation,the minimum ecological water requirement is 15.63 billion m3 in the 2000's,of which the dry,warm valley is 5.88 billion m3,and the dry,mild valley is 9.74 billion m3.If the water requirement for sediment transportation was neglected,the minimum ecological water requirement would be 5.83 billion m3 in the 2000's,of which the dry,warm valley is 2.10 billion m3,and the dry,mild valley is 3.73 billion m3;4)water requirement outside of the waterway occupied 5.7% of the total ecological water requirement;and 5)when considering water requirement for sediment transportation,the minimum ecological water requirement occupied 68.84% of the surface water amount and if the water requirement for sediment transportation was neglected,the minimum ecological water requirement would occupy 25.68% of the surface water amount.We suggest if ecological water requirement of fragile area was calculated,water requirement for sediment transportation should be taken into account.