Modelling of hydrological and environmental flow dynamics over a central Himalayan river basin through satellite altimetry and recent climate projections

Abstract

The Himalayan region is vulnerable to climate change, which is triggering extreme hydrological events. To understand the impact of climate emission scenarios on different hydrological flow dynamics of the Himalayan region, a thorough hydrological investigation is needed for improved water resource management. Hence, this research exemplifies the use of remote sensing, modelling techniques, and recent climate projections (CMIP5 and CMIP6) for the assessment of hydrological flow dynamics in the central Himalayan catchment. The SWAT model is calibrated/validated using gauge observation and satellite altimetry-derived river discharge and used for long-term hydrological simulations . CMIP6 models predicted that there would be a steady rise in high flows in all the projected scenarios. Flow duration curve for CMIP5 and CMIP6 models depicted that high flow of short duration would be frequent in future. The environmental flow components (EFCs) were calculated using the indicator of hydrologic alteration tool. The SWAT model simulations of hydrological and EFCs under CMIP6 climate projections are found to be significantly more vulnerable to climate warming than CMIP5, which could be due to socioeconomic pathway emission scenarios.

Questioning the use of ensembles versus individual climate model generated flows in future peak flood predictions: Plausibility and implications

“…Although the flood magnitudes can be expected to increase in the future relative to the baseline conditions, no distinct trend or pattern over time can be generalized. These predictions are quite similar to those made in other previous global (Hosseinzadehtalaei et al, 2021; Mori et al, 2021), regional (Kay et al, 2021; Mohanty and Simonovic, 2021; Wobus et al, 2021) and local studies (Devkota & Maraseni, 2018; Kumar et al, 2022; Mahato et al, 2021; Meema et al, 2021; Tabari et al, 2021).…”

“…Although the flood magnitudes can be expected to increase in the future relative to the baseline conditions, no distinct trend or pattern over time can be generalized. These predictions are quite similar to those made in other previous global (Hosseinzadehtalaei et al, 2021;Mori et al, 2021), regional (Kay et al, 2021;Mohanty and Simonovic, 2021;Wobus et al, 2021) and local studies (Devkota & Maraseni, 2018;Kumar et al, 2022;Mahato et al, 2021;Meema et al, 2021;Tabari et al, 2021). Flood magnitude of a given return period (estimated using Gumbel distribution) is a function of average and standard deviation of the considered flood series and the reduced variate, which in turn is a function of the return period (Appendix A).…”