Estimating floodplain sedimentation in the Laguna de Santa Rosa, Sonoma County, CA
- PDF / 1,884,196 Bytes
- 17 Pages / 595.276 x 790.866 pts Page_size
- 16 Downloads / 131 Views
ARTICLE
Estimating floodplain sedimentation in the Laguna de Santa Rosa, Sonoma County, CA Jennifer A. Curtis & Lorraine E. Flint & Cliff R. Hupp
Received: 15 May 2012 / Accepted: 23 October 2012 / Published online: 20 December 2012 # US Government 2012
Abstract We present a conceptual and analytical framework for predicting the spatial distribution of floodplain sedimentation for the Laguna de Santa Rosa, Sonoma County, CA. We assess the role of the floodplain as a sink for fine-grained sediment and investigate concerns regarding the potential loss of flood storage capacity due to historic sedimentation. We characterized the spatial distribution of sedimentation during a post-flood survey and developed a spatially distributed sediment deposition potential map that highlights zones of floodplain sedimentation. The sediment deposition potential map, built using raster files that describe the spatial distribution of relevant hydrologic and landscape variables, was calibrated using 2 years of measured overbank sedimentation data and verified using longer-term rates determined using dendrochronology. The calibrated floodplain deposition potential relation was used to estimate an average annual floodplain sedimentation rate (3.6 mm/year) for the ~11 km2 floodplain. This study documents the development of a conceptual model of overbank sedimentation, describes a methodology to estimate the potential for various parts of a floodplain complex to accumulate sediment over time, and provides estimates of short and long-term overbank sedimentation rates that can be used for ecosystem management and prioritization of restoration activities. Keywords Floodplain . Overbank sedimentation . Sediment deposition potential . Laguna de Santa Rosa . Russian River J. A. Curtis (*) : L. E. Flint U.S. Geological Survey, Water Resources Discipline, Sacramento, CA, USA e-mail: [email protected] C. R. Hupp U.S. Geological Survey, Water Resources Discipline, Reston, VA, USA
Introduction Most floodplain environments experience unsteady flow conditions during overbank events and sediment transfer across floodplains occurs through a combination of diffusion and convection processes (Pizzuto 1987; James 1985). Floodplain aggradation may occur laterally or vertically (Schumm and Lichty 1963) and the spatial variability of sediment accumulation tends to be complex (Asselmann and Middlekoop 1995; Middelkoop and Asselman 1998). The rates and patterns of overbank sedimentation depend upon a range of hydrologic and landscape variables including: magnitude, frequency and duration of inundation, sediment supply, and floodplain topography and roughness (Middelkoop and Van Der Perk 1998; Harter and Mitsch 2003; Phillips et al. 2007; Kiss and Sandor 2009; Schenk and Hupp 2010; Kiss et al. 2011). Generally, an increase in any of these factors could lead to an associated increase in the likelihood, or potential, of sediment deposition. Whether floodplain sedimentation is considered desirous or deleterious depends upon local conditions and the dominant physic
Data Loading...
