Abstract:

Ecological water requirement research is one of the most important parts of the sustainable use and development of water resources.There are numerous methods to calculate ecological water requirement.Based on the goal of protecting biodiversity，this paper combined the crosssection data of Niqu River and biological data，and then established the relationship between habitat index and flow.Based on the habitat index，including average water depth，water width，wetted perimeter，wetted area，hydraulic radius and weighted usable area (WUA)，the instream ecological water requirement of Niqu River which is in the water supply region of the West Route Project of SouthtoNorth Water Transfers Scheme (WRPSNWT) was calculated.The estimation of instream ecological water requirement could be a reference to decide how much water can be transferred in WRPSNWT.The result shows that the ecological water requirement is less than 10% of annual discharge when using the flow velocity，water depth，wetted area and hydraulic radius as habitat index.The ecological water requirement is 56%，48%，32% respectively when using water width，wetted perimeter，WUA as habitat index.At last, the minimum ecological water requirement of Niqu river is 193 m3/s and 298 m3/s at Nike and Zhuba station respectively，which is in the good scope of the result of Tennant method.So it can protect the fish habitat efficiently.