Modeling Nitrogen Loading on the Groundwater in Response to Land-Use Change

Effect of nutrient loading on the groundwater, specifically nitrogen loading, due to land-yuse change is a complex but understudied phenomena. Nitrate contamination of the yworld's groundwater supply poses a serious human health threat. This research is aimed yat better understanding how land-use affects nitrogen loading on the groundwater at a ylocal scale, and to examine the possibility of using orchard grass as a medium to reduce ynitrogen (i.e. nitrate) contamination of groundwater. y A 100 acre land having different land-use categories in the Centre County, PA, is used as ya study area. The Non Point Source (NPS) nitrogen loading on the surface runoff is yestimated using the Long-Term Hydrologic Impact Assessment (L-THIA) model. The ynitrogen laden runoff is then diverted over a strip of orchard grass, and the amount of ynitrogen leaching on groundwater beyond the root zone is estimated using the Grazing ySimulation Model (GRASIM). y A strong positive correlation is found between rainfall, nitrogen loading on the runoff, and ynitrate leaching to groundwater. The results show that routing storm runoff over a strip of yorchard grass detention base can reduce the amount of nitrogen leaching to the ygroundwater by 62 %. Thus, due to its ability to substantially reduce nitrogen yleaching, orchard grass strips (or, meadows) can be used as effective, low cost, and yenvironment friendly option for preventing groundwater contamination due to nitrate yleaching. The results underscore increasing use of grass and forested buffers for reducing ynutrient contamination of both surface water (streams, lakes), and the groundwater. y