PARENT SESSION
PM21 - Multimedia Models
Monday, 18 November 2002
8:00 AM to 6:30 PM
Exhibit Hall

(P402) GIS-ROUT Exposure Model: Characterization and Verification.

White-Hull, Charlotte^*,1, Dyer, Scott, Homer, Michael, Wang, Xinhao, ¹ Procter & Gamble Company, Cincinnati, Ohio, USA

ABSTRACT- The GIS-ROUT modeling system was developed to determine in-stream concentrations for conventional and user-defined pollutants for U.S. perennial streams, based upon per-capita chemical loadings and industry and wastewater treatment plant (WWTP) discharges. The model was parameterized using a framework of national U.S. EPA databases describing river characteristics (Reach File 1), industrial and WWTP discharges (Industrial Discharge File, Clean Water Needs Survey), and drinking water intakes (Safe Drinking Water Information System). Due to the nature of these data sources, various assumptions were made in order to create a viable model for determining concentration distributions at broad geographic scales. Thus, the accuracy of predicted concentrations is highly dependent on the correctness of the underlying data and associated model assumptions. For example, assumptions were required to include WWTP discharge locations not located on the RF1 river network. Another example included examining the suitability of RF1-based mean and low stream flows. Using consumer product monitoring data for two representative river systems, the model was shown to predict in-stream concentrations within a factor of two. The effects of chemical characteristics and market use patterns for consumer product chemicals on national concentration distribution patterns were also examined. Specifically, the importance of in-stream loss properties in the comparison of assessments using point of discharge benchmarks (e.g. EFAST, GRIDS model approach), versus incorporation of cumulative discharges was studied.

Key words: water quality, watershed model, chemical exposure, consumer product