Flood control and mitigation at Taunsa barrage on the Indus River in Pakistan | |
| Author | Taimoor, Amir |
| Call Number | AIT Thesis no.WM-16-20 |
| Subject(s) | Flood control Indus River (Pakistan) Flood damage prevention--Pakistan--Indus River |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Water Engineering and Management |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. WM-16-20 |
| Abstract | Taunsa Barrage is a large diversion structure built across the Indus river in the central Punjab province. The design discharge capacity of Taunsa Barrage is 28,300 cumecs. Two canals from right side of the barrage take off to irrigate 950,000 acres of DeraGhazi Khan and Rajanpur districts. From left side of the barrage, one link canal named TP link canal feeds the Chanab River at Punjnad barrage and Muzzafargarh canal to irrigate 8,38,000 acres of Muzzafargarhdistrict. The present study for flood control and mitigation mainly concerns with Taunsa Barrage as this had faced major flooding in the past causing huge loss to lives, infrastructure and economy. In the gigantic 2010 flood, the flood of 30,723cumecs against the designed discharge capacity of28,300 cumecs hit the barrage. Due to this exceptionally high flood wave, water level increased and crossed free board limits and caused breaching of left marginal bund approximately 10km upstream of the barrage. The whole left side area of the barrage including Kot adu and Muzzafar garh and many villages were inundated. Taunsa barrage does not have any storage reservoir. So it is required to increase the discharge capacity of the barrage which is costly. Another way to handle this extra discharge is to provide a passage (flood bypass channel) by providing a breaching section in the flood spur dike (Shank of Spur No.2) on right side of the barrage. The second method is adopted in this study. The study is carried out using MIKE 11 model for simulation of flood flows from 30km upstream to 10km downstream of the barrage. MIKE 11 Dam break erosion model is used to predict the breach outflow hydrograph through breach and the enlargement of the dam breaching section with time. Gated structure is used for regulation of flows at the barrage site using the control structure module provided in Mike 11. Discharge hydrograph and water level variation with discharge (Q-h relationship) is used as upstream and downstream boundary conditions respectively. The values of Manning's roughness coefficients are determined by trial and error by model calibration based on the previous flood data of 2010 which is the largest flood in the river. After model calibration, model verification is done for 2015 flood. The return periods of 2010 and 2015 floods are 420 years and 7 years respectively.MIKE 11 model is applied to predict the peak flood levels in the river for the peak discharges of 500 and 1000-yearreturn periods to suggest the new river levees bank levels. By using the calibrated model, the size of breaching section is studied to determine an adequate size to pass the extra flood flow. MIKE-11 dam break model is used to calculate the breach just upstream of the dam at the high flood level limit. Water levels in the bypass channel and at the bridge crossing of bypass channel are predicted using the breach outflow hydrographs computed from dam breach erosion model.The Mike 11model is used to predict thatthe water levels in the river remained below the free board limits after breaching of flood spur dike during high flood flows upstream of the barrage. Downstream of the barrage, over bank flows are predicted, and new levee bank levels are ivestimated using the peak water levels obtained during model simulations for the safe passage of flood flows in the river.After this study, there are two options to control and mitigate flood through Taunsa Barrage a). Providing flood bypass channel with flood spur dike b). Raising of left and right banks of Indus River to confine the flood water in the main channelCost analysis is done and found that the raising of bank is economical solution but in prevailing uncertain conditions of left marginal bank and keeping in view the peoples life and infrastructure damage in case of flooding, it is strongly suggestedto provide flood bypass channel and flood spur dike to control and mitigate flood. Early flood warning prior to the operation of breaching section can be given prior to flood arrival by running MIKE 11 model keeping in view of people safety and the evacuation time of people from the probable affected area to a safe place. The initial dam breaching sections should be properly inspected and prepared for activation in case of emergency. |
| Year | 2016 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no. WM-16-20 |
| 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) | Roa, Arturo Gementiza;Andreas, Sanyogita;Shrestha, Sangam |
| Scholarship Donor(s) | Punjab Irrigation Department-World Bank |
| Degree | Thesis (M. Eng.) - Asian Institute of Technology, 2016 |