Environmental Impact Evaluation of Spatial Management Practices Using Simulations with Spatial Data

Abstract

This paper addresses the diffuse [non-point source (NPS)] contamination problem by integrating the environmental impact analysis in production practices with the economics of spatial management methods. It employs a combination of geostatistical simulation and unsaturated zone transport modeling to evaluate the effect of spatial variability of soil-related parameters on NPS ground water contamination. Five management scenarios of spatially variable nutrient application are developed and evaluated on the basis of their impact on production agriculture and possible environmental pollution. The scenarios are evaluated considering the spatial variability of residual soil nitrate, yield, and hydraulic conductivity in the field. The process is applied to three realistic cases, differing in the extent of spatial variability, ranging from low to high variability. The modeling results indicate that the identified framework holds promise for evaluating spatial management practices in terms of production as well as protection of the environment. For example, results indicate that variable application of nutrient, based on spatially variable parameters, not only reduced the overapplication but also reduced the overall ground water contamination potential. However, the results suggest that the spatial management system may not necessarily result in a decrease in contamination loading for some fields, particularly those which exhibit a low variability of selected parameters. Furthermore, results indicate the presence of a break-even point between the benefits of spatial management technology and the efforts used in implementing this technology for various degrees of spatial variability. Beyond this point, the excess efforts appear to result in relatively small marginal benefits.