This report summarizes the results of the field work and analyses conducted as part of the Green-Duwamish Water Quality Assessment: Riparian Shade Characterization Sampling and Analysis Plan (King County 2004) and additional field work conducted on the Sammamish River during late summer of 2004. Analysis of recent high resolution Light Detection And Ranging (LiDAR) data are also evaluated in this report to assess their potential utility in conducting basin-scale riparian shade assessments. The results described in this report will provide more detailed information on riparian shade than was previously available for refinement of the Green River water quality model and allow incorporation of topographic and riparian shade effects into the Sammamish River model. This report also provides a starting point for incorporation of detailed riparian shade information into basin-scale HSPF watershed models that have been developed as part of King County’s Freshwater Program.

Based on the preliminary evaluation of the use of high-resolution LiDAR to remotely characterize vegetation cover (primarily tree height), a more spatially explicit and accurate assessment of tree cover appears to be possible. Using the LiDAR-derived tree heights and a uniform Canopy Density of 90 percent results in an encouraging correlation between model-predicted and observed shade (using hemispherical photographic analysis) when the measurements of shade are made in the center of the river channel.

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Riparian Shade Characterization Study (1.8 Mb)

Sampling and Analysis Plan