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

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.

Quantifying the impacts of land use/land cover change on the water balance in the afforested River Basin, Pakistan

“…The JRB is characterized by highly heterogeneous soil and land cover; main types of soil include Gleyic Solonacks (49%), Calaric Phaoeozems soil (23%), and Mollic Planosols soil (21%). The basin drainage area is covered by diverse land cover such as agriculture (31%), grass-sparse vegetation (37%), forest (28%), water (2%) and settlement (2%) (Saddique et al 2019b).…”

“…Based on the review literature and as far as the authors are aware, no previous study has been reported to date regarding LULC changes impact on the hydrology of the Jhelum River Basin (JRB). However, few studies (Mahmood andJia 2016 andSaddique et al 2019b) have assessed the impact of climate change on the stream flow of JRB forcing the Global Climate Models (GCMs) data. Therefore, this study filled this knowledge gap using different time periods land use data and employed SWAT hydrological model to simulate how these changes may affect the water resources of the basin.…”

Simulating the Impact of Climate Change with Different Reservoir Operating Strategies on Sedimentation of the Mangla Reservoir, Northern Pakistan

“…To envisage the impact of climate change on sedimentation at the Mangla Dam, future projected hydrological data (2018-2100) of all the tributaries of the Mangla Reservoir under RCP4.5 and RCP8.5 by Naeem et al [22,32] were used in the numerical model as the upstream boundary condition. Naeem et al [22,32] conducted a study on the Mangla watershed and explored the impacts of climate change on Mangla Dam hydrology using the soil and water assessment tool (SWAT).…”

“…To envisage the impact of climate change on sedimentation at the Mangla Dam, future projected hydrological data (2018-2100) of all the tributaries of the Mangla Reservoir under RCP4.5 and RCP8.5 by Naeem et al [22,32] were used in the numerical model as the upstream boundary condition. Naeem et al [22,32] conducted a study on the Mangla watershed and explored the impacts of climate change on Mangla Dam hydrology using the soil and water assessment tool (SWAT). For assessing the climate change impacts on flow regimes for three future periods (2011-2040, 2041-2070, and 2071-2100), three Global Circulation Models (GCMs) (CanESM2, BCC-CSM1-1, and MICROC5), and two representative concentration pathways (RCP4.5 and RCP8.5) with two downscaling methods (Statistical Downscaling Model (SDSM) and Long Ashton Research Station Weather Generator (LARS-WG)).…”

“…As a case study, we have selected the Mangla Reservoir in northern Pakistan. A few studies have been performed in the Jhelum River Basin (JRB) and its tributaries regarding the change in future precipitation and flows under the impact of climate change [20][21][22]. Further, only three studies have been carried out regarding incoming suspended sediment yield into the Mangla Reservoir [1,23,24].…”