An asset-based, holistic, environmental flows assessment approach

Abstract

This paper describes a site-based, ecological asset-based, holistic environmental flows assessment approach, and demonstrates its application to reaches of the Jiaojiang (Jiao River) Basin, Taizhou, Zhejiang Province, the People's Republic of China. The methodology broadly combines information on ecological and other assets associated with the river system (in this case, fish, vegetation, water quality and geomorphology) together with information that links these assets to aspects of the flow regime via hydraulic relationships. This is a site-based methodology, and it requires a medium-level effort and budget. The methodology hinges on being able to gain a basic understanding of the ecology and geomorphology of the stream system, having daily flow series' available, and having the capacity to develop hydraulic models. A comparison of the flow regimes recommended for the Jiaojiang reaches with recommendations derived from two hydrology-only methods found little correspondence. This was explained by the failure of hydrology-only methodologies to take into account the downstream change in the relationship between a river's geomorphic and hydrologic characteristics (i.e. expressed as hydraulics). Also, the ecological assumptions made by the hydrology-only methods cannot necessarily be applied in a generic way.