Modeling Shallow Groundwater Behavior Using Hydrus-1D and MODFLOW Models: Its Impact on Groundwater Salinity

Abstract

Shallow groundwater often plays an important role in soil salinization and crop production. A modeling study was conducted at experimental farm Nain, Panipat of ICAR-Central Soil Salinity Research Institute, Karnal, representing shallow saline groundwater region to simulate groundwater behavior and its impact on groundwater salinity in non-monsoon (winter and summer) and monsoon period using Hydrus-1D and MODFLOW analytical models. Result of the study indicate that net groundwater flow (inflow-outflow) in the study area was positive during the monsoon season while negative during winter and summer period. Continuous intrusion of ground water from outside farm area, seepage from pond and deep percolation from field resulted into rise in watertable depth and diluted saline groundwater at the end of monsoon period (July-Sep). However, a little spatial variation in hydraulic head (212.34-212.40 m) existed by the end of the monsoon season. The spatial variability maps of ground water salinity revealed that in monsoon period there was 13.19% reduction in the area of high to extreme salinity (8-20 dS m-1), while 3.8% and 10.2% increase in moderate (4-8 dS m-1) and non-saline (0-4 dS m-1) area, respectively. Overall, study provides quantitative understanding of multiple behaviors of shallow groundwater system with seasonal changes of drying and wetting cycles and its impact on groundwater salinity. Outcome of the study can be used to prioritize the area for implementing the groundwater management plan in the salt-affected areas having shallow groundwater.