Spatial and Temporal Nitrate Transport in Deep Heterogeneous Vadose Zone of India’s Alluvial Plain

Abstract

Nitrate percolates through deep vadose zone before entering groundwater. In the previous few years, researchers have only focused on the movement of nitrate up to the root zone depth of the crops. Few studies have been done on movement of nitrate in unsaturated region beyond root zone depth. In the present paper, spatial and temporal nitrate transportation in deep vadose zone has been studied. A case study, considering the hydrogeological features of alluvial plain, has been done for nitrate transportation in deep vadose zone. Heterogeneity in the subsurface layers of vadose zone has also been incorporated in this study. The fate of nitrate plume for varying concentration has been studied. The results in this study mainly quantify nitrate flux along with water flux, pressure head, and water content in various heterogeneous layers before entering groundwater table. Simulation results suggest that heterogeneity with dual permeability has a profound impact on nitrate transport in vadose zone.