To accomplish this, barrage officials partnered with local non-government groups, like the Punjab Rural Support Program PRSP , to help with public awareness. To this end, PRSP officials are helping run awareness campaigns and giving free high-yield wheat seeds to farmers with small plots of five acres or less. Standing close to a nearby canal, one farmer said the plan was appreciated. At present, about 80 children in the nearby canal community go to primary school in a derelict building as old as the barrage.
Only two rooms still have a roof and walls. Construction of two schools, two mosques, a public park, basic health unit, along with provision of natural gas and telephone lines for the canal community is part of the project. Public improvements are being completed first, before rehabilitation and modernization of barrage begins, to help ensure community support, says Arif. Some work at the barrage has already started. During the floods, as much as 15 times more water than usual surged through the barrage, and eroded the ground below.
Now boulders are building it up again. Back upstream, the Jinnah project is also tackling another British legacy. The Kalabagh iron bridge, built in , has gaping holes in wood planks covering its surface. Only locals still dare to cross it. Again, hoping to bolster community goodwill, the barrage project plans to put fresh concrete slabs on the bridge to make it passable again, says Arif. You have clicked on a link to a page that is not part of the beta version of the new worldbank. Will you take two minutes to complete a brief survey that will help us to improve our website?
Thank you for agreeing to provide feedback on the new version of worldbank. Thank you for participating in this survey! Your feedback is very helpful to us as we work to improve the site functionality on worldbank. Working for a World Free of Poverty. Who We Are News. Email Print. Tweet Share Share LinkedIn. The increase in water depth was just 2. It is already known that for a jump type-stilling basin, prevailing water depth is deficient by 8ft 2.
This demonstrates that the change in energy dissipation concept from impact to jump is not convincing at Jinnah barrage. Decrease in velocity upstream of the subsidiary weir, especially at higher discharges, is also not promising. Furthermore, the velocity remained fluctuating and higher in regions where the stone apron is placed. Chaudhry [10] noted that deep scour pits developed and the stone apron was completely washed away Figure 3a.
As shown in Figure 3b, the situation became worse when compared with the existing condition. Silt exclusion may be needed on the right side of the barrage to meet future anticipated changes in the pattern of flow feeding the Jinnah hydro power project.
Its construction and operation will be difficult with the addition of a subsidiary weir. During high flow, shingle may move along with the water, being deposited between the barrage and the subsidiary weir. Furthermore, massive Ballas has developed downstream of the barrage. The discharge capacity of the barrage may reduce in the presence of Ballas and the subsidiary weir, which could result in an increase of the upstream water levels. Construction of divide walls in the scoured area itself is a massive job.
Any failure of divide walls could be catastrophic, as the flow will be oblique and may change the river route. Furthermore, the repair and maintenance of two independent structures, as well as stone apron replenishment at three locations, would be expensive.
It suggests that a subsidiary weir ft m or ft m from the barrage crest may have serious hydraulic concerns if constructed. Either of the subsidiary weir arrangements would be larger, and costlier than the existing barrage. Table 2 shows the salient dimensions of subsidiary weirs, various rehabilitation scenarios and the barrage itself.
The Feasibility Report [8] and Alternative Report [7] noted that the loose stone apron downstream of the concrete block floor displaces excessively at Jinnah barrage. Velocity and kinetic energy remains higher and the stone apron will be launched if not placed in the proper size and at a stable slope.
One possible solution could be the extension of a concrete block floor at the slope of for a length of about 25ft 7. This arrangement makes the barrage safe from ill effects of retrogression, scouring and launching of the stone apron.
The proposal was tested on the physical model Figure 4 and it worked well for gated and ungated flow. Furthermore, the stone apron finishes within the existing divide walls without affecting the function of fish ladders. It is a logical, economical and hydraulically suited solution. Instead of filling the scoured area with stone, a second stilling basin could be added just at the end of the existing concrete block floor Figures 2 and 5. The additional stilling basin will act as an integral part of the existing barrage.
In this arrangement a cumulative hydraulic performance of both the basins is to be considered. The second stilling basin floor may be fixed at EL, which was the same as for the subsidiary weir proposed by the Feasibility Report [8]. Furthermore, the end sheet pile was proposed at EL, which protects the stilling basin from the ill effects of local scouring and retrogression. A concrete block floor with inverted filter to mitigate seepage and uplifts could be developed underneath the existing barrage and proposed structure [7].
An end sheet pile, along with inverted filter arrangement overlaid by concrete block floor, could control seepage, uplift and movement of fines. Gaps could be provided through the weir to facilitate shingle movement along with water.
Furthermore, the arrangement finishes within the existing divide walls and will not change the function of the undersluices and fish ladders. This arrangement also avoids the possibility of piping underneath the barrage. The proposal was tested on the physical model and it worked well. It is more expensive than stone replenishment, but may be provided if needed. The Jinnah barrage downstream glacis length is 24ft 7. Deficiency in glacis length cannot be addressed without lowering the stilling basin floor level.
Therefore, the energy dissipation system at Jinnah barrage cannot be categorized as jump type; rather it is impact cum jump type. Various rehabilitation scenarios are discussed in terms of their hydraulic functioning and financial impact.
An extension of the divide walls will develop three channels between the barrage and subsidiary weir, and their construction would be challenging as deep scour pits already exist. Failure of divide walls could be catastrophic, as repair work would be very difficult. The replenishment of the loose stone apron at the launching slope is a more hydraulically suited and economical rehabilitation solution and may be adopted at the Jinnah Barrage, although the provision of a second stilling basin in the weir section of the barrage would also be an efficient rehabilitation solution.
Since it can be completed within the existing divide walls; the functions of the undersluices, fishladders and navigation bay may not be affected. It is more expensive than stone replenishment but could be utilised if a more permanent solution is needed. The author is thankful to Mr. Shakoor, Senior Model Expert, for technical discussions and valuable suggestions.
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