Abstract: Ecological water demand of river is currently one of the hot fields in researching water resources,and its calculation method is the focus.So far,the calculation method of ecological water demand of river is generally divided into four categories,i.e.the historical discharge method,hydraulic rating method,habitat method and holistic method.Through comparative analysis of the advantages and disadvantages of various research methods,it was considered that the Tennant method is more suitable for the rivers in arid area where the hydrological data are insufficient.However,the ecological water demand calculated with this method based on the percentage of average annual discharge cannot reflect the annual and seasonal discharge variation.Therefore,in this study the typical annual discharge was used to replace the average annual discharge,thus the Tennant method was improved,and the ecological water demand of the river section from Wenquan Station to Bole Station of the Bortala River was calculated.The result showed that the minimum ecological water demands of the river section in common season and peak season were 0.22×10⁸ m³ and 1.34×10⁸ m³,and they were increased by 4.5% and 48.5% compared with those before improving the method,respectively.The calculated results could reflect the big seasonal runoff change of the Bortala River.

Key words: river, ecological water demand, calculation method, Tennant method, seasonal runoff modulus ratio coefficient, Bortala River, Xinjiang