HYPOTHESIS-BASED FIELD EXPERIMENTS IN SUPPORT OF REGULATED RIVER REHABILITATION

The Spawning Habitat Integrated Rehabilitation Approach (SHIRA) is a CALFED-sponsored, scientifically peer-reviewed framework for addressing hydrogeomorphic and ecologic problems on regulated rivers. At present SHIRA is being used on the Mokelumne, Trinity, and Yuba Rivers to assess baseline conditions, design reach and sub-reach scale rehabilitation projects, and track post-project outcomes. Drawing on the variability inherent in these 3 different basins, a large palette of in-channel design elements has been developed and evaluated to determine their utility in producing naturalized fluvial processes and biological functionality at the 0.1-100 m2 spatial scales fish actually experience a river. Key design elements that have been implemented in field-based adaptive-management experiments and whose habitat value has been assessed 2003-2005 include slope creation below dams, lateral riffle variations, artificial-redd dune fields, and controlled backwater effects through downstream riffle crest modification. Hydraulic, geomorphic, and biological results from hypothesis testing and field experimentation of these design elements will be presented and discussed. Detailed results are available at http://shira.lawr.ucdavis.edu.