Climatic and Anthropogenic Controls on Correlated Discharge from US West Coast Rivers (Invited)
Abstract
Most river basins along the US West Coast are generally small, less than 15,000 km2, and tend to flood quickly following rain events. The storm systems that deliver rain to the coastal mountain ranges are considerably larger than the river basins such that multiple basins receive precipitation within hours of each other. Subsequently, these proximal rivers often disperse freshwater and sediment to the coastal ocean at relatively the same time. Many conceptual and numerical models of coastal processes may underestimate the delivery, dispersal and burial of sediment on the continental shelves as they often assume point source delivery of water and sediment from a single river. The reality seems to speak to the fact that a collection of smaller river basins may be synchronously delivering sediment all along a stretch of coastline. Hydrologic records from 62 coastal watersheds stretching along the US west coast from the Canadian to the Mexican border were acquired from the USGS river gauging network, this included over 100 gauging stations with records varying in length. This data mining effort allowed for a detailed analysis of the timing of flood peaks to the actual coastlines, rather than just correlation between gauging stations. Distinct coastal groupings were found that have rivers that deliver freshwater and sediment to the continental shelves at the same time, indicating plume mixing and different oceanic hydrodynamic regimes than would be indicated by traditional coastal sediment transport models. Also seen were larger scale climatic controls on the watershed relationships and alteration of the flood signals due to anthropogenic changes within the watershed. Extensive flood control networks, differences in population centers and floodplain modification within these basins all contributed to unexpected deviations from the correlation patterns.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMGC22A..02F
- Keywords:
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- 1803 HYDROLOGY Anthropogenic effects;
- 1821 HYDROLOGY Floods;
- 3002 MARINE GEOLOGY AND GEOPHYSICS Continental shelf and slope processes