Regional water flow and pesticide leaching using simulations with spatially distributed data

• Published in: Geoderma 1991-05, Vol.48 (3), p.245-269
• Main Authors: Petach, M.C., Wagenet, R.J., DeGloria, S.D.
• Format: Article
• Language: English
• Subjects: AGUAS SUBTERRANEAS; CALIDAD DEL AGUA; Earth sciences; Earth, ocean, space; EAU SOUTERRAINE; Engineering and environment geology. Geothermics; Exact sciences and technology; GROUNDWATER; LEACHING; LESSIVAGE DU SOL; LIXIVIACION; MODELE DE SIMULATION; MODELOS DE SIMULACION; PESTICIDE; PESTICIDES; PLAGUICIDAS; Pollution, environment geology; QUALITE DE L'EAU; SIMULATION MODELS; Soils; Surficial geology; WATER QUALITY
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/0016-7061(91)90047-W

Simulation modeling of water and chemical movement and techniques of Geographical Information Systems (GIS) were used to integrate, condense and summarize the large-scale (order of kilometers) behavior of spatially variable soils to provide management guidance on issues related to pesticide movement in soil. A one-dimensional, convection-dispersion-based solute transport model was used to simulate the movement of four classes of chemicals through layered soils for a 7 km X 10 km site near Albany, New York. The site was divided into a 163 X 112 grid (0.4 ha per cell), with multiple model executions used as a means of incorporating the influence of spatial variability of soil hydraulic properties into the study. Pedotransfer functions based on regression equations were used to relate soil physical properties to the mean and variance of hydraulic properties within each cell. Each model execution used hydraulic properties selected from frequency distributions derived from these parameters. Land use, soil, and slope maps were overlain with a Geographical Information System (GIS) to stratify the grid cells appropriate for modeling. Time series plots for mean and variance of water flux, solute mass, and solute flux were produced based on 25 1-year simulations for each hydraulic group, using local climatic data. Two climatic conditions were analyzed, a very ‘wet’ year (90th percentile of the population of total annual precipitation) and a mean precipitation year. The calculated solute fluxes are discussed in terms of the implications for pesticide management and for estimating potential leaching hazards at the study site.