GIS based Identification of Risk to Nutrient Exposure in the Large Agricultural Lands of India – Towards Better Decision-making

Application of excess nutrients such as fertilizers is a significant and sometimes even major component of ground water pollution. Diffuse inputs of nutrients and contaminants to the ground water are related to runoff generated from precipitation in a catchment. Catchment’s response depends on site conditions and its physical properties. This implies that the analysis of diffuse fluxes from the land surface to the ground water requires an area-differentiated analysis of water fluxes for a catchment. This requires a GIS application that is capable of assembling, storing, analyzing and displaying the regional interactions and inter-relationships of land, soil and water. Simulation and modeling of total runoff, groundwater recharge, and plant available water as a function of the regional interaction of the climate, soil, hydro-geology, topography and land use conditions in the river basin using GIS is achieved here. A GIS-based model has been developed for large river basins in India, and has been applied to the Upper Yamuna basin, to quantify the exchange probability of plant available soil water, which can be taken as a measure to determine the nutrient and contaminant leaching risk of a site. It was found that with the available large-scale databases and methods regional patterns of the total runoff could be simulated successfully. In this way, about 7,500 km of the total 12,000 km of the Upper Yamuna basin were classified as areas sensitive to nutrient and contaminant leaching.