保障河流生态需水是实现流域水资源可持续利用的重要基础。本文在综合考虑水生生物对于河流水深要求以及生态需水年际差异的基础上，对传统生态水力半径法进行了改进，并以青海湖裸鲤为指示生物研究了青海湖流域两条主要河流（布哈河、沙柳河）的生态需水特征。结果表明：（1） 改进生态水力半径法计算结果较为合理并可以满足维持河流基本生态功能的需要，不考虑年际差异的生态需水计算结果将被显著高估；（2） 1958-2009年布哈河和沙柳河年生态需水量多年平均分别介于1.45×108-2.64×10⁸、1.26×10⁸-1.85×10⁸m³；（3） 布哈河和沙柳河4-5月生态缺水量多年平均分别为0.29×10⁸、0.21×10⁸m³。因此，改进生态水力半径法是计算河流生态需水的一种新型有效方法。

The guarantee of Environmental Flow Requirements (EFRs) of rivers is an important foundation for the sustainable utilization of water resources. By considering the water depth requirement of aquatic organisms and distinguishing the inter-annual difference of EFRs, the traditional ecological hydraulic radius approach was improved. Then the Adapted Ecological Hydraulic Radius Approach (AEHRA) was used to study the EFRs characteristics of two main rivers (Buha River, Shaliu River) in Qinghai Lake watershed using Naked Carp (Gymnocypris przewalskii) as the biological indicator, and the results indicate that (1) EFRs calculated by AEHRA is reasonable and could satisfy the demand for keeping the basic ecological function of rivers. EFRs would be significantly overestimated, if its inter-annual difference is not considered. (2) Annual EFRs of Buha River and Shaliu River were 1.45×10⁸m³-2.64×10⁸m³, 1.26×10⁸m³-1.85×10⁸m³, respectively in the period of 1958 to 2009. (3) Average ecological water shortages of Buha River and Shaliu River were 0.29×10⁸m³, 0.21×10⁸m³, respectively in April and May. Consequently, AEHRA is a new and effectual method for calculating the EFRs of rivers.