Potential impacts of climate change on water resources of Haro River Watershed in Pakistan
Climate change has resulted in changes in the hydrological fluxes and water distribution across the globe. Pakistan, which is home to almost 200 million people, is a particularly vulnerable country due to poverty, population growth and lack of resources. However, studies quantifying future climat...
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Format: | Thesis |
Language: | English |
Published: |
2019
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Online Access: | http://psasir.upm.edu.my/id/eprint/104237/1/SAIMA%20NAUMAN%20-%20IR.pdf http://psasir.upm.edu.my/id/eprint/104237/ |
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Summary: | Climate change has resulted in changes in the hydrological fluxes and water distribution
across the globe. Pakistan, which is home to almost 200 million people, is a particularly
vulnerable country due to poverty, population growth and lack of resources. However,
studies quantifying future climate change on water catchment regions in the country are
limited due to multiple issues with data and modelling uncertainty. This research aims
to quantify projected changes in the climate and its consequent impact on the
streamflows of Haro River, the source of water for Khanpur Dam. Firstly, the climate
change input is obtained by selecting one out of five downscaled General Circulation
Model (GCM) outputs based on the highest coefficient of determination (R2) value from
a regression against observed meteorological dataset. The baseline and future
meteorological parameters from the selected GCM are then bias corrected using the
observed meteorological dataset. For future climate, two Radiative Concentration
Pathways (RCP) 4.5 and 8.5 are considered. at two stations, namely Murree (P-1) and
Islamabad (P-2). Next, a hydrological model for the basin is developed using the Soil
and Water Assessment Tool (SWAT) to integrate the meteorological data and produce
simulation of streamflows for the baseline (1976-2005) and future periods (2006-2095).
The calibration, validation, uncertainty analysis and the sensitivity analysis of the SWAT
Model is conducted in Sequential Uncertainty Fitting 2 (SUFI-2) algorithm. Finally, the
change in streamflows is projected through a relative comparison between baseline and
future flows on monthly and seasonal scale. The study found that the maximum
(minimum) temperature at P-1 is expected to increase by 3.1°C (3.2°C) under RCP 4.5
and 4.0°C (4.3°C) under RCP 8.5 in the future. Precipitation is expected to rise from
8.9% under RCP 4.5 to 14.3% under RCP 8.5. Similarly, at P-2, the maximum
(minimum) temperature is anticipated to increase by 3.3°C (3.3°C) under RCP 4.5 and
4.1°C (4.2°C) under RCP 8.5. Precipitation is projected to increase between 15.4% (RCP
4.5) and 23.1% (RCP 8.5) compared to the baseline scenario. SWAT produced good
model performance with Nash Sutcliffe Efficiency (NSE) and R2 values of 0.80 (0.77)
and 0.82 (0.77) respectively during the calibration (validation) period. Simulation of
baseline and future streamflows using the calibrated SWAT indicates an increase from
average annual baseline streamflows of 7.7 m3/s to 8.7 m3/s (9.3 m3/s) under RCP 4.5
(RCP 8.5). Maximum streamflows expected during the month of July, are projected to
increase from baseline streamflow of 21.3 m3/s to 28.2 m3/s (32.6 m3/s) under RCP 4.5
(RCP 8.5). In summer season, compared to baseline streamflows of 13.1 m3/s, the
streamflows are expected to be 4.2 m3/s (6.8 m3/s) higher under RCP 4.5 (RCP 8.5). This
study will help the policy makers in conceiving prudent schemes for effective utilization
of water supply throughout the year. The new policies may focus on increasing water
storage capacity of the dam reservoir in the future resulting from projected increase in
streamflows. |
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