Simulating the Impact of Climate Change on the Hydrological Regimes of a Sparsely Gauged Mountainous Basin, Northern Pakistan

Saddique Saddique,Bernhofer Bernhofer,Usman Usman

doi:10.3390/w11102141

Saddique Saddique, Bernhofer Bernhofer + Show 1 more

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https://doi.org/10.3390/w11102141

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Abstract

Projected climate changes for the 21st century may cause great uncertainties on the hydrology of a river basin. This study explored the impacts of climate change on the water balance and hydrological regime of the Jhelum River Basin using the Soil and Water Assessment Tool (SWAT). Two downscaling methods (SDSM, Statistical Downscaling Model and LARS-WG, Long Ashton Research Station Weather Generator), three Global Circulation Models (GCMs), and two representative concentration pathways (RCP4.5 and RCP8.5) for three future periods (2030s, 2050s, and 2090s) were used to assess the climate change impacts on flow regimes. The results exhibited that both downscaling methods suggested an increase in annual streamflow over the river basin. There is generally an increasing trend of winter and autumn discharge, whereas it is complicated for summer and spring to conclude if the trend is increasing or decreasing depending on the downscaling methods. Therefore, the uncertainty associated with the downscaling of climate simulation needs to consider, for the best estimate, the impact of climate change, with its uncertainty, on a particular basin. The study also resulted that water yield and evapotranspiration in the eastern part of the basin (sub-basins at high elevation) would be most affected by climate change. The outcomes of this study would be useful for providing guidance in water management and planning for the river basin under climate change.

Highlights

The fifth assessment report of the Intergovernmental Panel on Climate Change (IPCC, AR5) points out that the earth air temperature has increased by 0.85 ◦ C for 1881–2012 and for each of the recent past three decades
In the Soil and Water Assessment Tool (SWAT) model, the whole catchment is divided into sub-basins, and a sub-basin further delineated into multiple Hydrological Response Units (HRUs) that consist of homogeneous land-use, soil, and topography
The Soil and Water Assessment was for the simulation of hydrological in JRB.regimes model calibrated and was used for the simulation ofregimes hydrological in JRB

Summary

Introduction

The fifth assessment report of the Intergovernmental Panel on Climate Change (IPCC, AR5) points out that the earth air temperature has increased by 0.85 ◦ C for 1881–2012 and for each of the recent past three decades. It has been projected that the mean temperature will increase over 1 ◦ C under the low emission scenario (RCP2.6) and over 4 ◦ C under the high emission scenario (RCP8.5) [1]. An increasing temperature trend has been observed in the Himalayan basins [2,3,4]. The most often used method for impact assessment of climate change on hydrological cycles is by forcing the outputs of Global Circulation Models (GCMs) into hydrological models [6]. An ensemble approach of different GCMs, which could show various scenarios, is recommended

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