Spatio-temporal dynamics of hydrologic changes in the Himalayan river basins of Nepal using high-resolution hydrological-hydrodynamic modeling

•High-resolution hydrological-hydrodynamic modeling is conducted over all river basins in Nepal.•River flows at all quantiles persistently declined during 1999–2018 at most downstream regions.•Both high and low flows strongly modulated the evolution of inundation extent and flood occurrence.•Terrestrial water storage persistently declined in recent years due to groundwater depletion.