Assessment of climate change impact on water resources and hydropower in the Jhelum River Basin, Pakistan | |
| Author | Mahmood, Rashid |
| Call Number | AIT Diss. no.WM-13-01 |
| Subject(s) | Climatic changes--Pakisaan--Jhelum River Basin Water resources--Pakistan--Jhelum River Basin |
| Note | A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Engineering in Water Engineering and Management, School of Engineering and Technology |
| Publisher | Asian Institute of Technology |
| Series Statement | Dissertation ; no. WM-13-01 |
| Abstract | The increasing concentration of greenhouse gases in the atmosphere has been changing the climate of the world and has been causing global warming. The warmingleads to changes in evapotranspiration, precipitation, soil moisture, and infiltration. Precipitation changesaffect water availability in soils, rivers and lakes, domestic and industrial water supply and demand, hydropower generation, and agricultural productivity. Thus, the changes in climate cause some serious effects on the hydrological system. To date, these effects areassessed by Global Climate Models (GCMs). However, these models have course spatial resolution which is not suitable to assess the impacts of climate changes on hydrologic system at local/regional scale. Thus, many downscaling techniques have been developed to overcome the spatial mismatch between GCM and regional scale. The focus of this study is to investigate the changes in climate variables (temperature and precipitation), and their consequences on the stream flow and hydropower under the IPCC emission scenarios in the Jhelum River basin,Pakistan and India. Moreover, this study also covers the evaluation of several GCMs for selecting a suitable GCM, and the evaluation of SDSM (Statistical Downscaling Model) developed by monthly and annual sub-models for downscaling max temperature, min temperature, and precipitation.The evaluationof four GCMs (CSISRO-Mk2, CGCM2and CCSRIES, and HadCM3), selected according to the data availability, is performed by assessing three statistical indicators; coefficient of determination(R²), root mean squareerror(RMSE), and standard deviation(б).These indicators are calculated by using the monthly time series (max temperature, min temperature, and precipitation) of observed and raw GCMs (A2 and B2) for the period of 1991-2009. The results show that the temperature (max and min temperature) is underestimated by all GCMs in magnitude, although the pattern is well captured by each GCM. In case of precipitation, no one of GCMs captures the variation as well as magnitude of observed precipitation. Nonetheless, HadCM3 is selected for downscaling of temperature and precipitation on the basis of above mentioned indicators, graphical visualization, and data availability. This study evaluates the statistical downscaling model (SDSM) developed by annual and monthly sub-models for downscaling maximum temperature, minimum temperature and precipitation, and assesses future changes in climate in the Jhelum River basin, Pakistan and India. Additionally, bias correction is applied on downscaled climate variables. The mean explained variances of 66, 76,and 11% for max temperature, min temperature,and precipitation respectively, are obtained during calibration of SDSM with NCEP predictors, which are selected through a quantitative procedure. During validation, average R² values by the annual sub-model (SDSM-A)—followed by bias correction using NCEP, H3A2 and H3B2—lie between 98.4 to 99.1% for both max and min temperature, and 77 to 85% for precipitation. As for the monthly sub-model (SDSM-M), followed by bias correction, average R² values lie between 98.5 to 99.5% for both max and min temperature and 75 to 83% for precipitation. These results indicate a good applicability of SDSM-A and SDSM-M for downscaling max temperature, min temperature,and precipitation under H3A2 and H3B2 scenarios for future periods of the 2020s, 2050s,and 2080s in this basin. Both sub-models show a mean annual increase in max temperature, min temperature,and precipitation. Under H3A2, and according to both sub-models, changes in max temperature, mintemperature and precipitation are projected as 0.91-3.15°C, 0.93-2.63°C ivand 6-12%, and under H3B2, the values of change are 0.69-1.92°C, 0.56-1.63°C and 8-14% in 2020s, 2050s and 2080s. These results show that the climate of the basin will be warmer and wetter relative to the baseline period. SDSM-A, most of the time, projects higher changes in climate than SDSM-M. It can also be concluded that although SDSM-A performed well in predicting mean annual values, it cannot be used with regard to monthly and seasonal variations, especially in the case of precipitation unless correction is applied.The impacts of climate change on the stream flow under IPCC emission scenarios,A2 and B2, are assessed by usingdownscaled temperature and precipitation data as inputs to HEC-HMS. The model is calibrated and validated using observed daily stream flow for the period of 1982-89 and 1978-81 respectively at various stream flow gauges in the Jhelum River basin. HEC-HMS includes a loss method (Deficit and Constant), a transform method (SCS-unit hydrograph),as well as abase flow method (Recession)for calculating total stream flow from the basin, and temperature index is used to take care of snow fall. Performance indicators (e.g., Nash-Sutcliffe efficiency, coefficient of determination and percent deviation) and graphical visualizationsbetween observed and simulated stream flow indicate that the variations and magnitudes of observed data are well captured by the simulated data during calibration and validation. The changes in 2020s (2011-2040), 2050s (2041-2070), and 2080s (2071-2099) are assessed relative to baseline period (1971-2000). Thus, the simulated discharge, under A2, shows a mean annual increase in 2020s, 2050s, and 2080s at all gauging station except at Domel in 2050s, as do the simulated discharge under B2 except at Muzaffarabad in 2050s. The mean annual discharge at Azad-Pattan, the main gauging station that contributes about 87% as annual inflow to Mangla reservoir, is projected to increase about 24 to 30% under A2 and B2at Azad-Pattan stream gauge.According to the flow changes at Azad-Pattan stream gauge under A2 and B2, the high flows in the Jhelum basin are projected to decrease in 2020s and 2080s, with 1-7%, but increase in 2050s, with 6-6.7%. The median flows are predicted to increase in all three periods, with 20-36% increase w. r. to baseline. On the other hand, the low flows could be increased in 2020s and 2080s, with 2-8%, and decreased in 2050s under both A2 and B2 scenarios, with 12-14% |
| Year | 2013 |
| Corresponding Series Added Entry | Asian Institute of Technology. Dissertation ; no. WM-13-01 |
| Type | Dissertation |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Babel, Mukand S.; |
| Examination Committee(s) | Sutat Weesakul ;Tripathi, Nitin Kumar ;Shrestha, Sangam; |
| Scholarship Donor(s) | Higher Education Commission of Pakistan; |
| Degree | Thesis (Ph. D.) - Asian Institute of Technology, 2013 |