AUTHORS: Peter Cada, Michelle Schmidt – Tetra Tech, Inc.; Megan Mehaffey, Anne Neale – USEPA ORD
ABSTRACT: Planning for a sustainable future should include an accounting of services currently provided by ecosystems such as erosion control. Retention of soil not only maintains but improves soil fertility, improves water retention, and decreases sedimentation in streams and rivers thereby reducing the need for costly flood control, dredging of reservoirs and waterways, while maintaining habitat for fish and other species important to recreational and tourism industries. Previous efforts leveraged landscape-scale geospatial data available for the CONterminous United States (CONUS) to estimate sediment erosion (RUSLE-based, Renard, et al. 1997) employing recent geospatial techniques of sediment delivery ratio (SDR) estimation (Cavalli, et al. 2013). These efforts led to a quantitative approximation of the ecological services provided by vegetative cover type with respect to protecting soils from the erosion processes of detachment, transport, and deposition.Recent efforts have examined the potential impacts that changes in climate may have on sediment pollution by altering rainfall erosivity (R factor in RUSLE method). These alterations were developed using the late-21st century using Global Climate Model (GCM) data. GCM data from the aCMIP5 was statistically downscaled to the same temporal and spatial resolution as PRISM (4 km, daily) using the Multivariate Adaptive Constructed Analogs (MACA) method (Abatzoglou and Brown, 2012). Daily precipitation and temperature data were retrieved for the CONUS from 5 GCMs with relatively low seasonal and regional biases (Mehran et al, 2014; Toreti et al, 2013; Zhu et al, 2014).Monthly hindcast (1990 – 2005) and futurecast (2070 – 2099) R factors were computed for each GCM. Relative change rasters were created for each GCM and were then used to generate future seasonal R rasters for each GCM, and subsequently seasonal sediment yields. Final products are HUC-12 scale outputs of estimated sediment loads associated with each future climate scenario for the CONUS.
