Study on Ecological Water Requirement of Dry Valleys in the Upper Reaches of the Dadu River
大渡河上游干旱河谷区生态需水研究

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.