NLEAP/GIS approach for identifying and mitigating regional nitrate-nitrogen leaching

Improved simulation-based methodology is needed to help identify broad geographical areas where potential NO₃-N leaching may be occurring from agriculture and suggest management alternatives that minimize the problem. The Nitrate Leaching and Economic Analysis Package (NLEAP) model was applied to estimate regional NO₃-N leaching in eastern Colorado. Results show that a combined NLEAP/GIS technology can be used to identify potential NO₃-N hot spots in shallow alluvial aquifers under irrigated agriculture. The NLEAP NO₃-N Leached (NL) index provided the most promising single index followed by NO₃-N Available for Leaching (NAL). The same combined technology also shows promise in identifying Best Management Practice (BMP) methods that help minimize NO₃-N leaching in vulnerable areas. Future plans call for linkage of the NLEAP/GIS procedures with groundwater modeling to establish a mechanistic analysis of agriculture-aquifer interactions at a regional scale.