Hydroecology and river restoration : 3 Ripe for research and synthesis

6 [1] Research at the intersection of hydrology and ecology is central to a future in which 7 human and ecological needs for water are met. We briefly identify several compelling 8 research questions at this intersection, then focus on a critical research area central to 9 hydroecology: river and stream restoration. Challenges in this area include the 10 development of science to evaluate the effectiveness of restoration, particularly the 11 cumulative effects of many small projects, to restore ecosystem processes under highly 12 constrained conditions such as below dams or in urban settings, to push some aquatic 13 ecosystems beyond ‘‘restoration’’ to boost their ability to perform functions of value to 14 society, and to identify feedbacks associated with critical thresholds beyond which 15 restoration is not possible. Meeting these research challenges requires research at the 16 interface of social science and the disciplines of hydrology, geomorphology, ecology, and 17 engineering, but hydroecology will be the central science.