| Author | Javed, Waqas |
| Call Number | AIT Thesis no.WM-16-29 |
| Subject(s) | Sedimentation and deposition--Pakistan--Diamer Bhasha Dam
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| Note | A thesis submitted in partial fulfillment of the requirement for the degree of Master of Engineering in Water Engineering and Management |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. WM-16-29 |
| Abstract | Sedimentation is one of the major problem for the reservoirs and it is reducing the capacities of the reservoirs at rate of 1% annually worldwide (Mahmood, 1987). Reservoirs in Pakistan are also under a great threat of sedimentation and major reservoirs have loss 33% of their original capacities due to sedimentation. Agri culture is backbone of Pakistan economy and about 70% population of Pakistan is related directly or indirectly to agriculture. The location of the study is the proposed Diamer Bhasha Dam and its reservoir of 10 BCM capacity in Pakistan. The dam is proposed upstream of the large Tarbela dam on the Indus River. Proper management of sediments for the proposed Bhasha Dam can enhance the life of its reservoir. Among various reservoir sediment management methods, flushing has been opted because of economy and prevailing site conditions. The present study focuses on effective flushing of deposited sediment across the width and along the length of the reservoir to reduce, excessive loss in capacity of the reservoir with time and hence increase in the life of res ervoir. Various effective flushing schemes in term of discharge release with time and duration of releases are studied and the most effective scheme is recommended. There are many models available which can be used for simulation of reservoir sediment de position and flushing. In the present study, due to narrow shape of the Bhasha reservoir, a 1 - D mathematical model HEC - 6KC has been used. The HEC - 6KC model is an extended version of the original HEC - 6 model which was developed by the Hydrologic Engineering Center, US Corps of Engineers (HEC - 6KC User Manual, 1987). The Model was calibrated for river bed profile, river water surface profile at two stations near the dam site and sediment load at Bhasha dam site in the year 1969 - 1993. Model verification was don e with river water surface profile of third station located nearly 1 Km upstream dam site and sediment data at Bhasha dam site from year 1994 - 2003.Ackers and White equation developed in 1973 is used for total load sediment transport of coarse materials whereas equation for transport of clay and silt ( Krone, 1962) as in original HEC - 6 has been used in present study. Distribution of deposited sediment in the reservoir is computed by the HEC - 6KC model and the useful life of the dam has been estimated to be 70 years when there is no flushing or sediment removal. Four different scenarios for flushing with respect to time interval, duration of flushing, discharge and level for drawdown flushing have been used to find out the effective flushing strategy. With th e current design of flushing outlets it has been estimated that the life of reservoir can be extended to more than 120 years using different flushing scenarios. First flushing is proposed not earlier than 30 years of commencement of Bhasha dam operation. T his is to avoid accelerating movement of deposited sediment delta toward the Bhasha dam and considering Tarbela dam at downstream. Sediment Balancing Ratio (SBR) and Long Term Capacity Ratio (LTCR) are the two indicators used to determine the effectiveness of flushing. It is recommended that if the capacity of flushing outlets is increase from 5,130 to 6,300 m 3 /sec, SBR value of nearly 1 can be achieved whereas LTCR of 48% can be attained which will fulfill the criteria mentioned by Atinkson (1996) for successful flushing. This recommended flushing scheme will make Bhasha Dam reservoir sustainable. |
| Year | 2016 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. WM-16-29 |
| Type | Thesis |
| School | School of Engineering and Technology |
| Department | Department of Civil and Infrastucture Engineering (DCIE) |
| Academic Program/FoS | Water Engineering and Management (WM) |
| Chairperson(s) | Tawatchai Tingsanchali |
| Examination Committee(s) | Shrestha, Sangam;Andriyas, Sanyogita;Roa, Arturo Gemetiza |
| Scholarship Donor(s) | Punjab Irrigation Department;World Bank |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2016 |