AI SearchAssessment of future climate and its impact on streamflow : a case study of Bagmati Basin, Nepal
Call Number: AIT Thesis no.WM-09-05 Material type:
SeriesSeries: Asian Institute of Technology. Thesis ; no. WM-09-05Publication details: Pathum Thani, Thailand : Asian Institute of Technology, 2010 Description: 107 leaves : illSubject(s): Online resources: Dissertation note: Thesis (M.Eng.) - Asian Institute of Technology, 2009 Summary: Climate Change is a global phenomenon but the trend and extent of its impact varies in spatial and temporal scale demanding local scale studies. Bagmati river basin in Nepal is currently facing the problems of water stress and floods which may be aggravated due to climate change. This research is carried out to quantify the future changes in climate and its impact on streamflow in the Bagmati Basin. The research methodology includes GCM selection and downscaling of GCM data, extreme climate indices analysis and assessment of future water availability under SRES scenarios A2 and B2. Out of five GCMs (Hadcm3, CSIRO, CCSR/NIES, CGCM3 and ECHAM4) analyzed, Hadcm3 provided statistically better results to represent present day precipitation while in case of temperature all GCMs show statistically reliable performance. Downscaling with SDSM model has well estimated both mean and extreme values of temperature whereas it could not estimate the extreme events of precipitation but the mean daily precipitation result is reliable. Scenario A2 indicates the diminish in precipitation amount during the dry period and increase during the wet period. However, scenario B2 shows increase during both periods. Maximum and minimum temperature extremes are increasing with higher rates during summer than the winter indicating more severe impact of warming during summer. The increase in heavy precipitation events R20 (number of days with precipitation > 20mm), R35 (number of days with precipitation > 35mm) and Rx5day (maximum 5-day precipitation) will lead to increase in frequency and magnitude of floods in the future. Similarly, the increase on the trend of consecutive dry days (CDD) and decrease of consecutive wet days (CWD) reflects the occurrence of more intense droughts in the future. The hydrological simulation shows that according to scenario A2, water availability will be decreased during pre-monsoon period leading to increase in water stress during dry period while flow will increase during monsoon period indicating increase in flood problems. However, scenario B2 shows increase in water availability during both wet and dry periods. With these expected changes on future climate and water availability in the basin, appropriate adaptation and management strategies are to be developed.
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A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Water Engineering and Management
Thesis (M.Eng.) - Asian Institute of Technology, 2009
Climate Change is a global phenomenon but the trend and extent of its impact varies in spatial and temporal scale demanding local scale studies. Bagmati river basin in Nepal is currently facing the problems of water stress and floods which may be aggravated due to climate change. This research is carried out to quantify the future changes in climate and its impact on streamflow in the Bagmati Basin. The research methodology includes GCM selection and downscaling of GCM data, extreme climate indices analysis and assessment of future water availability under SRES scenarios A2 and B2. Out of five GCMs (Hadcm3, CSIRO, CCSR/NIES, CGCM3 and ECHAM4) analyzed, Hadcm3 provided statistically better results to represent present day precipitation while in case of temperature all GCMs show statistically reliable performance. Downscaling with SDSM model has well estimated both mean and extreme values of temperature whereas it could not estimate the extreme events of precipitation but the mean daily precipitation result is reliable. Scenario A2 indicates the diminish in precipitation amount during the dry period and increase during the wet period. However, scenario B2 shows increase during both periods. Maximum and minimum temperature extremes are increasing with higher rates during summer than the winter indicating more severe impact of warming during summer. The increase in heavy precipitation events R20 (number of days with precipitation > 20mm), R35 (number of days with precipitation > 35mm) and Rx5day (maximum 5-day precipitation) will lead to increase in frequency and magnitude of floods in the future. Similarly, the increase on the trend of consecutive dry days (CDD) and decrease of consecutive wet days (CWD) reflects the occurrence of more intense droughts in the future. The hydrological simulation shows that according to scenario A2, water availability will be decreased during pre-monsoon period leading to increase in water stress during dry period while flow will increase during monsoon period indicating increase in flood problems. However, scenario B2 shows increase in water availability during both wet and dry periods. With these expected changes on future climate and water availability in the basin, appropriate adaptation and management strategies are to be developed.
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