Assessing the Influence of Land Cover Changes on the Baseflow regime: A case of Bharathapuzha River

Abstract

The Bharathapuzha River, Kerala’s second-longest river, has experienced significant hydrological shifts over recent decades, notably in its baseflow regime. As baseflow represents the groundwater-fed component of streamflow critical for sustaining river health during dry periods, understanding its variability is essential. This study investigates how land cover changes—particularly deforestation, urban expansion, and agricultural intensification—have influenced baseflow patterns over a 30-year period. The research adopts a multidisciplinary approach, integrating remote sensing and GIS-based land cover classification (using Landsat imagery from 1993–2023) with hydrological modelling. The Base Flow Index (BFI) was calculated using the HYSEP digital filter method within the USGS framework, and temporal trends in baseflow, streamflow, precipitation, and groundwater levels were analysed. The Mankara gauging station served as the primary data point for sub-watershed-level analysis. Results show a consistent decline in BFI in areas where natural vegetation was converted into built-up or intensively farmed land, indicating reduced infiltration and aquifer recharge. The study identifies critical intervention zones and proposes watershed-scale strategies including riparian restoration, managed aquifer recharge, afforestation, and urban land-use regulation. By integrating qualitative stakeholder inputs with quantitative analysis, it emphasizes the need for incorporating baseflow sustainability metrics into river basin planning and water governance. The findings contribute to the broader discourse on climate-adaptive river management and underline the importance of land system stewardship in preserving groundwater-supported river flows. Keywords: Base Flow Regime, Land Cover, Base Flow Index (BFI), Streamflow Analysis, Watershed Management, Remote Sensing and GIS