Hydrologic versus hydraulic predictors of ecological responses to changing flow regimes: an evaluation of traditional versus emerging methods

The world’s rivers are undergoing unprecedented changes in their flow regimes due to climate change and/or river restoration projects. In all cases, we require an ability to predict the ecological impacts of these changing flow regimes, both from the point of view of mitigating negative impacts of flow degradation; and planning and evaluating the benefits of flow restoration. Currently, many predictions of ecological responses are made using empirical models that attempt to relate ecological conditions to changes in hydrologic descriptors of the flow regime. However, attempts to derive generalizable and transferable relationships among different regions have generally been unsuccessful, and it has been hypothesized that hydraulic descriptions of flow regimes will have much greater power to predict ecological responses. This project will evaluate the relative efficacy of hydrologic versus hydraulic descriptors of flow regime as predictors of ecological responses to changing flow regimes. A Hydraulic-based model of ecological response will be developed with the aim of generating hydraulic descriptors for data-rich and data-poor river systems, and its performance will be compared to that of hydrology-based models for well-studied and less studied organisms.