Approaches for assessing long-term annual yields of highway and urban runoff in selected areas of California with the Stochastic Empirical Loading and Dilution Model (SELDM)

Abstract

Division of Environmental Analysis, helped design the study and provided oversight, information, and data for the study. Bhaskar Joshi and Joshua Gualco of the California Department of Transportation, Division of Environmental Analysis, and Dipen Patel of the California State University, Office of Water Programs, provided a report review that improved the content and presentation of information in this report. The authors thank Laura Medalie of the U.S. Geological Survey (USGS) for assistance with the geographic and water-quality compilations. The authors also thank Alana Spaetzel and Adam Stonewall of the USGS for providing thoughtful and thorough technical and editorial reviews that greatly improved this report and the associated data release model archive.

Assessing Potential Effects of Climate Change on Highway-Runoff Flows and Loads in Southern New England by Using Planning-Level Space-for-Time Analyses

“…TP was chosen as the water quality constituent for discussion because of the abundance of EMC measurements for this constituent in the region. These simulations were performed as part of a SELDM modeling study by the USGS in cooperation with the FHWA and Connecticut, Massachusetts, and Rhode Island DOTs; an archive of the simulations is publicly available in Granato et al (19). An empirical relation from the literature was used to evaluate the potential effects of climate change on stormwater treatment.…”

“…These analyses, however, were limited to comparisons between temperature effects on the settling velocity of sediment and variations in grain size and specific gravity. The climate change analyses described in this paper were not included in the original SNE study (19); this paper represents a new interpretation of existing simulation results.…”

“…Precipitation statistics covering a wide range of climatic conditions were needed to perform a space-for-time analysis of climate change. In this study precipitation statistics from National Oceanic and Atmospheric Administration (NOAA) hourly precipitation data stations with at least 25 years of data from 1965 to 2006 were used to simulate current conditions with SELDM (17,19). Forty-five selected NOAA stations within and adjacent to the SNE area were selected to represent conditions within SNE and provide a range of statistics that may characterize future conditions within the region (Figure 1, Table 1).…”

“…The dilution factor and annual-yield analyses depend on the current SNE precipitation statistics (Table 1). These results are derived from 147 highway-runoff yield analyses conducted by using SELDM for a highwayrunoff study in SNE (19). The stormwater treatment analysis is based on current and future temperature analyses produced using the CMIP tool (Figure 2) and applied to an empirical sediment settling equation (17).…”

“…The stormwater treatment analysis is based on current and future temperature analyses produced using the CMIP tool (Figure 2) and applied to an empirical sediment settling equation (17). SELDM simulations for this study include an analysis to estimate highway-runoff yields (loads per acre) using highway-runoff statistics with local SNE precipitation statistics from 45 individual precipitation gages (19). The 147 highway-runoff simulations include three sets of water quality statistics for low, high, and median geometric-mean concentrations (15th, 50th, and 85th percentiles).…”