Assessment of influencing level of rainfall and physical factors on groundwater level for a semi-arid flat terrain watershed using grid-based geospatial analysis: a case study from Lower Palar Basin, Tamil Nadu, India

Understanding natural phenomena with the help of modern scientific approaches helps to reach sustainable solutions for current and future water-related problems. In this context, present study aims to assess relative influencing level of physical factors in controlling groundwater level, using a novel grid-based delineation technique, in Lower Palar River Basin, in Kanchipuram and Chengalpattu districts of South India. The influencing factors viz-a-viz: rainfall, soil texture, land use/land cover, terrain slope, geomorphology, lithology, and drainage characteristics were considered for the study. Archived data (2011 to 2020) of monthly rainfall at four rain gauge stations and monthly groundwater level of 22 locations, soil texture, lithology, and geomorphology data were considered for the study. SRTM digital elevation model with 30-m resolution was used for analyzing drainage characteristics and terrain slope. Thematic maps for considered factors were prepared, using common grid delineation method in GIS platform that divided study area into 52 grids, to inter-relate the discrete and continuous parameters with groundwater level. Results indicate that level of influence increases in the order of precipitation followed by lithology, land use/land cover, terrain slope, geomorphology, infiltration number, and soil texture. The study shows groundwater resilience is highly influenced by soil texture and infiltration number compared to other factors considered. It can be concluded that grid-based delineation successfully identifies grids with significant influence of individual factors by comparing with groundwater resilience. Common grid-based delineation method proves to be more effective in assessing groundwater resilience and can be used more efficiently in groundwater studies.

Automated summary

Understanding the relative influence of physical factors on groundwater levels is crucial for sustainable solutions to water-related problems. This study used a novel grid-based delineation technique to assess the influence of factors such as rainfall, lithology, and land use on groundwater levels in the Lower Palar River Basin in South India. The results showed that rainfall had the highest level of influence, followed by lithology and land use. Soil texture and infiltration number were found to have a significant impact on groundwater resilience. The grid-based delineation method proved to be effective in identifying the grids with significant influence and can be used efficiently in groundwater studies.