Unveiling hidden perspectives: Examining COVID-19 impact on non-perennial river flow across ungauged river segments and anthropogenic footprint on the hydrological cycle

Pennar River Basin, India. The COVID-19 pandemic offered a one-of-a-kind opportunity to examine how the ecosystem reacts to diminished human interference. This study examines the rejuvenation potential of the ungauged lower Pennar River, India, between pre and post-COVID. Satellite-derived bathymetry ( SDB ) models are developed to estimate flow depth for ungauged river segments. Meteorological drought is assessed using the standardized potential evapotranspiration index ( SPEI ) and the standardized precipitation index ( SPI ), whereas groundwater drought is evaluated using the standardized groundwater table index ( SGWTI ). The correlation between SPEI , SPI, and SGWTI is employed to ascertain that groundwater drought influences river cross-section due to anthropogenic or natural forcings. The newly proposed index of river rejuvenation susceptibility ( RRS ) is assessed by integrating weights derived from the Analytical Hierarchy Process ( AHP ) and Fuzzy AHP with the magnitude of the aforementioned indices. The findings indicate a low to moderate correlation between the SPEI , SPI and SGWTI , emphasizing that groundwater drought in the study area is attributable to human interventions such as pumping. The fact is cross-validated using the stage of extraction data. The RRS of the lower Pennar River is identified to have increased considerably during COVID-19 due to a significant reduction in groundwater extraction, as proven by depth-duration curves and standardized total water storage anomalies ( STWSA ). • A novel concept explores river rejuvenation patterns via RRS , DDC s, and STWSA . • The ML based SDB method is employed to estimate water depth at ungauged segments. • Pennar River is affected by groundwater drought due to anthropogenic activities. • Pennar rejuvenated considerably during COVID-19 due to reduced human activities. • Natural and anthropogenic forcings influence the SRPN and RRS in the study area.