Application of SWAT in Hydrological Simulation of Complex Mountainous River Basin (Part II: Climate Change Impact Assessment)

Suresh Marahatta,Laxmi Prasad Devkota,Utsav Bhattarai,Deepak Aryal,Dibesh Shrestha

doi:10.3390/w13111548

Abstract

This study aims at analysing the impact of climate change (CC) on the river hydrology of a complex mountainous river basin—the Budhigandaki River Basin (BRB)—using the Soil and Water Assessment Tool (SWAT) hydrological model that was calibrated and validated in Part I of this research. A relatively new approach of selecting global climate models (GCMs) for each of the two selected RCPs, 4.5 (stabilization scenario) and 8.5 (high emission scenario), representing four extreme cases (warm-wet, cold-wet, warm-dry, and cold-dry conditions), was applied. Future climate data was bias corrected using a quantile mapping method. The bias-corrected GCM data were forced into the SWAT model one at a time to simulate the future flows of BRB for three 30-year time windows: Immediate Future (2021–2050), Mid Future (2046–2075), and Far Future (2070–2099). The projected flows were compared with the corresponding monthly, seasonal, annual, and fractional differences of extreme flows of the simulated baseline period (1983–2012). The results showed that future long-term average annual flows are expected to increase in all climatic conditions for both RCPs compared to the baseline. The range of predicted changes in future monthly, seasonal, and annual flows shows high uncertainty. The comparative frequency analysis of the annual one-day-maximum and -minimum flows shows increased high flows and decreased low flows in the future. These results imply the necessity for design modifications in hydraulic structures as well as the preference of storage over run-of-river water resources development projects in the study basin from the perspective of climate resilience.

Highlights

Traditional energy sources along with human labour and draught transport were replaced initially by coal and by oil in the early 1900s for powering machines and transportation [1,2]
The projected precipitation by all global climate models (GCMs) for all time windows (IF, MF and Far Future (FF)) is most likely to increase in both RCPs except MPI-ESM (MF, FF) and HadGEM2 (IF), in the case of RCP
Our results are comparable with these, showing that projected precipitation by almost all GCMs for all time windows (IF, MF and FF) is most likely to increase in both RCPs

Summary

Introduction

Traditional energy sources along with human labour and draught transport were replaced initially by coal and by oil in the early 1900s for powering machines and transportation [1,2]. Since the beginning of the industrial age, the ability to harness and use different forms of energy has led to global economic growth and an increase in production and consumption, which enabled people to perform increasingly productive tasks and to improve the living standards of billions of people [4,5]. Scientific evidence indicates that huge emissions of CO2 and other greenhouse gases (GHGs) in the atmosphere are associated with the increasing use of fossil fuel [6,7]. The era of the industrial revolution can, be taken as the starting point of climate change (CC) as the scientific community has defined it today [8].

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Methods

Results

Discussion

Conclusion