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Coupled geomorphic and habitat response to a flood pulse revealed by remote sensing
Author(s) -
Harrison Lee R.,
Pike Andrew,
Boughton David A.
Publication year - 2017
Publication title -
ecohydrology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.982
H-Index - 54
eISSN - 1936-0592
pISSN - 1936-0584
DOI - 10.1002/eco.1845
Subject(s) - hydrology (agriculture) , habitat , flood myth , channel (broadcasting) , environmental science , floodplain , overbank , fish migration , sediment transport , sediment , ecosystem , river morphology , geology , fluvial , ecology , geomorphology , geography , geotechnical engineering , archaeology , engineering , structural basin , biology , electrical engineering
Despite a growing consensus on the importance of floods in structuring river ecosystems, predicting the geomorphic and habitat response to specific flood pulses across a range of scales remains challenging. We used a large reservoir release in a semiarid river to characterize geomorphic and habitat responses to a flood pulse, using an integrated field, remote sensing, and modeling approach. Large‐scale geomorphic changes were observed as a result of the flood, including lateral migration of the river channel, gravel bar formation, and development of off‐channel chutes. Spatial patterns of gravel storage varied with downstream distance from a large dam, with the upper 15 km experiencing a net sediment deficit and the lower 65 km undergoing net deposition. The longitudinal trends in gravel transport and storage reflected differences in channel gradient and predicted values of sediment mobility. The flood lowered the channel by an average of −0.5 m and roughly doubled the areal extent of pools, by incising new pools in curved reaches and in areas where the river abutted valley walls and terraces. The increased pool abundance provided greater habitat connectivity and was predicted to have positive impacts on anadromous steelhead, providing up to a 3‐fold increase in the number of juvenile fish the river could support. Results from this study highlight the value of using flood pulses as opportunities to learn about river behavior, and for testing the degree to which physical processes can help restore the form and function of river ecosystems.