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Regional Projects

Russian River Scenarios

This subset of maps illustrate the differences in flood extents and depths under conditions of an open or closed inlet at the Russian River mouth near Jenner, California. The results were computed with CoSMoS version 2.0 (same as that used for the region between Point Reyes and Point Arena) using the same 100-year coastal storm event as in previous simulations (deepwater significant wave height = 10.93 m, peak wave period = 17 s, incident peak wave direction = 260° and storm surge and sea level anomalies = 0.40 m), but with a higher fluvial discharge rate that approaches the flood stage in Guerneville (9.75 m or 32 feet, USGS National Water Information System). These forcing conditions were all simulated for present day sea level and for five half-meter sea-level rise (SLR) scenarios (0.50 m, 1.0 m, 1.5 m, 2.0 m, and 5.0 m). In all, a total of 12 flood maps are provided.

Closed inlet scenarios were developed by raising the bathymetry across the inlet to an elevation exceeding the SLR plus maximum tide level. The inlet was assumed non-erodible, but overwash was allowed. Areas that appear wet across the closed inlet are because modeled extreme water levels overwashed the the inlet bar.

The figures below provide examples of changes made to the digital elevation model (Figure 1) and simulated time-series of water levels within the estuary (Figure 2) for the open and closed inlet conditions. Both figures are for the 1 m SLR scenario. Analyses of these simulation results and additional simulations with varying discharge rates are currently (spring 2017) being worked up and summarized in a manuscript for potential journal publication.

Figure 1. Maps showing elevations of the seabed and nearshore terrain for the (A) open and (B) closed inlets. (C) Cross-section along the red line in A and B showing the differences in the open and closed inlet elevations.

Figure 2. Plots showing numerically computed time-series of water levels immediately landward of the Russian River mouth near Jenner for the 1 meter sea-level rise scenario. (A) Water levels for the 100-year coastal storm and background river flows. (B) The same 100-year coastal storm but with river flows that yield a flood stage of ~32 feet in Guerneville.