Sayed Sanaullah Shah, Babar Shaikh and Badar Munirsuparco.gov.pk/downloadables/Poster_Flood...
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Background The river flooding of 2010 in Sindh paralyzed life in effected regions for over a period of 3 months. The swallowing River Indus caused Tori breach near Kandhkot on right bank in Sindh province downstream of Guddu Barrage as shown in Fig-1, while left bank was effected by a breach near Kot Almo. The embankment failures can be attributed to various factors including super flood, deforestation, reduction of effective floodplain due to utilization of land for agriculture purposes, braided channel flow and channel meandering. Historically this flood plain is vulnerable and mega flooding also occurred during 1942 effecting same areas as during floods of 2010. Keeping in view the present and past history of this floods, this plain has been selected for detailed analysis Study Area Figure -2 depicts study area stretching between Guddu and Sukkur Barrages. Fig -1: Flood 2010 and location of Tori Breach Fig -2: Study Area- Elevation Model of study area closed within levees Objectives • Mapping of effective flood plain from Guddu to Sukkur Barrage • Assessment of flood vulnerability in Guddu to Sukkur flood plain • Flood modeling through HEC-RAS & GIS Methodology The levees and discharge data was collected form Sindh Irrigation Department. HEC-RAS in collaboration HEC-GeoRAS was used to simulate the results. Water surface profiles are computed from one cross section to the next by solving the energy equation with an iterative procedure called Standard Step Method. The cross sections with respect to water levels were exported to ArcGIS to generate water surface raster which is overlaid on elevation model for flood inundation mapping. Methodology flow diagram and landuse of study area are shown in Fig- 3 & 4. Sayed Sanaullah Shah, Babar Shaikh and Badar Munir Fig -4: Landuse of Study Area Fig -5: Simulated and Observed (2010) Flood Inundation Mapping Fig -6: Longitudinal Profile of Study Area at Various Discharges Vulnerable Area; Left Levee Vulnerable Area; Right Levee a) 350,000 Cusecs b) 550,000 Cusecs c) 700,000 Cusecs d) 900,000 Cusecs e) 1,100,000 Cusecs f) Vulnerable areas at 1,100,000 Cusecs Results and Discussions Fig -7: Vulnerable Areas Fig -8: Proposed inundation channels Recommendations 1. Rehabilitation and strengthening of indentified vulnerable levees. 2. Inundation channels from Guddu Barrage to Manchar lake and Thar desert as shown in Fig-8. Simulated inundation mapping was validated with 2010 observed flood as shown in Fig-5. Vulnerable points are marked where the free board value is considerably less, as shown in Fig-6(f) and Fig-7. Fig -3: Methodology Flow Diagram
Transcript of Sayed Sanaullah Shah, Babar Shaikh and Badar Munirsuparco.gov.pk/downloadables/Poster_Flood...
Background
The river flooding of 2010 in Sindh paralyzed life in effected regions for over aperiod of 3 months. The swallowing River Indus caused Tori breach nearKandhkot on right bank in Sindh province downstream of Guddu Barrage asshown in Fig-1, while left bank was effected by a breach near Kot Almo. Theembankment failures can be attributed to various factors including super flood,deforestation, reduction of effective floodplain due to utilization of land foragriculture purposes, braided channel flow and channel meandering. Historicallythis flood plain is vulnerable and mega flooding also occurred during 1942effecting same areas as during floods of 2010. Keeping in view the present andpast history of this floods, this plain has been selected for detailed analysis
Study AreaFigure -2 depicts study area stretching between Guddu and Sukkur Barrages.
Fig -1: Flood 2010 and location of Tori Breach
Fig -2: Study Area- Elevation Model of study area closed within levees
Objectives
• Mapping of effective flood plain from Guddu to Sukkur Barrage• Assessment of flood vulnerability in Guddu to Sukkur flood plain• Flood modeling through HEC-RAS & GIS
Methodology
The levees and discharge data was collected form Sindh Irrigation Department.HEC-RAS in collaboration HEC-GeoRAS was used to simulate the results. Watersurface profiles are computed from one cross section to the next by solving theenergy equation with an iterative procedure called Standard Step Method. Thecross sections with respect to water levels were exported to ArcGIS to generatewater surface raster which is overlaid on elevation model for flood inundationmapping. Methodology flow diagram and landuse of study area are shown in Fig-3 & 4.
Sayed Sanaullah Shah, Babar Shaikh and Badar Munir
Fig -4: Landuse of Study Area
Fig -5: Simulated and Observed (2010) Flood Inundation Mapping
Fig -6: Longitudinal Profile of Study Area at Various Discharges
Vulnerable Area; Left Levee
Vulnerable Area; Right Levee
a) 350,000 Cusecs b) 550,000 Cusecs c) 700,000 Cusecs
d) 900,000 Cusecs e) 1,100,000 Cusecs f) Vulnerable areas at 1,100,000 Cusecs
Results and Discussions
Fig -7: Vulnerable Areas
Fig -8: Proposed inundation channels
Recommendations
1. Rehabilitation and strengthening of indentified vulnerable levees.2. Inundation channels from Guddu Barrage to Manchar lake and Thar
desert as shown in Fig-8.
Simulated inundation mappingwas validated with 2010 observedflood as shown in Fig-5.
Vulnerable points are markedwhere the free board value isconsiderably less, as shown inFig-6(f) and Fig-7.
Fig -3: Methodology Flow Diagram
