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Chotiari reservoir, an integral part of drain project
Colonel Muhammad Safir Tarar
ARTICLE (March 10 2003) : The Chotiari Water Reservoir Project, built as an integral part of the Left Bank Outfall Drain Project Stage-I, is the first Wapda project of the Jamali government.
It has been constructed to outcrop the backward areas under Sanghar and Mirpurkhas districts.
Irrigated agriculture is the backbone of Pakistan's economy. The agriculture sector is the major user of water and its consumption will continue to dominate water requirements.
The major user of water for irrigation is the Indus Basin Irrigation System. About 106 million acre feet of water out of 157 million acre feet of surface water are being diverted annually for irrigation while around 48 million acre feet are being pumped out from ground water reservoirs.
With large cultivable land base of 77 million acres of which only 36 million acres are canal commanded.
Pakistan still has the additional potential of brining about 22.5 million acres of virgin land under irrigation.
Pakistan is fast heading towards a situation of water shortage with increasing population.
The surface water availability per capita was 5650 cubic metres in 1951, which reduced to 1400 in 2000.
The minimum water requirement to avoid being a "water short country" is 1000 cubic meters.
In the year 2012 Pakistan will have reached the stage of "acute water shortage". To avoid this situation Wapda has come up with a National Development Programme Vision 2025 for the country.
As a first leg of the national water resources and hydropower development programme Gomal Zam Dam, Mirani Dam projects, Greater Thal Canal, Kachhi Canal, Rainee Canal projects and Mangla Dam Raising Project have already been undertaken to handle the coming situation.
The agriculture sector plays a pivotal role in national economy and stays as the backbone to the economic structure of Pakistan.
The province of Sindh has played an important role in the agricultural sphere, still there are vast tracks of land yet to be brought under plough.
In the environment of Sindh continued diversion of Indus water without drainage inevitably resulted in water-logging and salinity problems which in turn lead to depressed crop yields and eventual loss of cultivable land.
Water was added without proper drainage facilities and as a result of it the water table began to rise.
The ground water being saline accumulated on average one tonne of salt to every irrigated acre in Sindh, every year.
The surrounding high temperature drew up the underground saline water through soil capillaries and was evaporated between the surface and the crop root zone leaving behind the salt.
The Left Bank Outfall Drain Project, a major engineering project to provide an integrated development of irrigation and drainage in an area of 1.28 million acre, situated on the left bank of River Indus under the command of Sukkur Barrage, Chotiari Reservoir was planned as an integral part of the drain project.
Chotiari Reservoir is to enlarge the storage capacity existing systems to supplement the irrigation supplies.
The 55 km long earth embankment with a maximum height of 30 ft. Chotiari Reservoir has a capacity of storing 0.7 MAF of water during floods in the Indus River.
It is to be released in winter and early summer months to the Lower Nara Canal below Makran Weir.
The water, otherwise drawn from Nara Canal, will now be available for the remodelled Jamrao Canal command in Sanghar and Mirpurkhas districts in LBOD project area.
Chotiari Reservoir is an off-stream reservoir on the Nara and Lower Canal Systems and a part of Left Bank Outfall Drain (LBOD) Staged-I Project which was otherwise not viable without the construction of Chotiari Reservoir and remodelling of irrigation system which will increase the benefit cost ratio from 0.9:1 to 1:3.1 and Economic Internal Rate of Return (EIRR) from 11.48% to 16.64%.
Due to rising water tables and the associated salinisation of the non-cropped areas, fallow land is decreasing and abandoned land is increasing.
As a result the farmers are forced to intensify cropping on their best land.
Increased water supplies initially increase the cropped area but at the expense of decreasing the non-cropped area which reduces the dry drainage effect and allow the water table to continue rising.
Some areas have already reached a point where pockets of cultivated land are surviving because they are surrounded by a saline waste.
This saline waste is providing them dry drainage required to maintain the water table at a low enough level for cropping.
The Chotiari Water Reservoir Project will go a long way to bulge the rear areas of Sanghar and Mirpurkhas districts.
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