Diffuse Source Particulate-Matter Pollution Modeling in a Semi-Urbanized Agricultural Basin in Japan Using Process-Based WEP and an Erosion-Transport Model

摘要

The present study aimed at further improving the process-based WEP (Water and EnergynProcesses) hydrologic model, by coupling a soil erosion-transport model to introduce particle-bound pollutantncomponent. The WEP model, initially developed for the extensive analysis of water and energy budgetsnat catchment scale, was later enhanced by incorporating material transport component (nitrogen andnphosphorus; N and P), targeting integrated river basin management and decision support. The modelninvolved a discharge-based process to simulate both N and P, and was validated using data in Yata RivernBasin, Japan, considering land use, plant acreage, fertilizer loading, plant nutrient uptake and crop harvestnin respective administrative units. Although the model could adequately reproduce the dissolved N (DN)ncomponent as per the measured river N concentrations at selected observation points, particulate N andnP (PN, PP), and dissolved P (DP) components were not satisfactorily simulated. In the present study, annattempt was made to incorporate PN and PP transport as soil absorbed constituents, by introducing anprocess-based sediment erosion, transport, deposition and associated pollutant load simulation procedures.nThe present modeling results indicate that PN and PP loads were better correlated with suspended solidsn(SS) in the stream and the model forecasting capabilities are noticeably enhanced, as verified based on thenresults obtained for simulation years 2001-2002 using pre-collected data (SS, PN and PP), signifying majornpathways of nutrient losses in the basin.