Understanding impact of Rainfall Intensity Distribution and Climatology on Recharge and Baseflow in tropical Hard-rock Aquifers of South India

Processes controlling surface-groundwater interaction in terms of recharge and baseflow have been a topic of pursuit in the hydrological research community. The groundwater recharge and baseflow in hard-rock aquifers is significantly impacted by rainfall pattern, aquifer characteristics, weathering/soil condition, topography, land use and land cover. Analysis of the recharge and baseflow process in tropical semi-arid hard-rock aquifer regions of southern India is crucial due to heavily tailed monsoon system prevailing in the region, heterogeneity of aquifers in terms of fractures and lineaments and presence of several man-made irrigation tanks along with the drainage network. Process uncertainties in groundwater recharge simulation due to impact of climate change on vegetation and resulting changes in evapotranspiration can significantly impact groundwater projections. Poor representation of diffused and focused recharge pathways and inadequacy in capturing the feedback among climate, land use and groundwater systems are other factors introducing uncertainties. Finally, the gaps in long-term observational data make it challenging to assess the impact of climate change. A taluk scale study conducted in Karnataka State of India indicated a significant correlation between the rainfall intensity distribution and climatology on groundwater recharge in Hard-rock aquifers. The current study targets to add a baseflow component represented by a 2D groundwater model and extend the previous study to a larger scale. The primary objectives of the study are to estimate the long-term groundwater recharge and baseflow trends and evaluate their association with rainfall and climatological variability. As the projected climate scenarios reflect higher frequency of high-intensity rainfall, it becomes essential to evaluate the impacts of varying rainfall patterns on the surface-subsurface processes.