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PESTICIDE LEACHING ANALYTICAL MODEL AND GIS-BASED APPLICATION IN AGRICULTURAL WATERSHEDS
Citation:
Zhang, Z. AND M M. Hantush*. PESTICIDE LEACHING ANALYTICAL MODEL AND GIS-BASED APPLICATION IN AGRICULTURAL WATERSHEDS. ASCE 2000 Joint Conference on Water Resources Engineering and Water Resources Planning and Management (CDROM), Minneapolis, MN, July 30 - August 02, 2000. American Society of Civil Engineers (ASCE), Reston, VA, 1-10, (2000).
Impact/Purpose:
information
Description:
Groundwater contamination by pesticides and other organic pollutants has been detected across agricultural areas and is on the increase. Because groundwater monitoring is too costly to define the geographic extent of contamination at such large scales, indirect methods are needed to estimate the fate and concentration of pesticides in the subsurface and assess the potential for groundwater contamination that may result from applications of pesticides. In this paper, two analytical solutions of an one-dimensional transport model which describe the transport and fate of pesticides in the soil, were integrated with a geographic information system (GIS) to estimate spatial solute leaching distributions and to create groundwater vulnerability assessment maps. The GIS-based models use process-based equations that consider advection and complete mixing to simulate solute transport and to predict pesticide transport in both space and time. To demonstrate its capabilities, the modeling approach was applied to an agricultural watershed region in the mid-Atlantic coastal plain using the data from a limited monitoring study in this region. The impact of processes, such as net infiltration, biochemical degradation, adsorption and advection on the spatial and temporal distribution of pollutant mass fluxes to groundwater were investigated. Based on this evaluation, it was determined that the GIS-based models can be tremendously useful screening tools to determine the risk of groundwater contamination by pesticides and to analyze existing groundwater contamination problems in susceptible agricultural areas.