To say that dams are crucial for a country’s sustainable socioeconomic progress is to state the obvious. Water security has emerged as a key theme of public policy discourse at global level as countries are taking immediate steps to replenish their water resources by building more and more dams and making judicious and efficient use of water.
For the last many years, Pakistan has been grappling with the acute energy crisis, which has stymied the growth of economy and has exposed domestic households to immense inconvenience. According to Economic Survey of Pakistan 2013-14, the energy crisis caused an erosion of 2-3% of Gross Domestic Product (GDP) as factories were shut leading to massive lay-offs, businesses were moved abroad and foreign direct investment declined.
Pakistan’s future lies in unlocking tremendous hydropower potential of 60,000 MW that still remains untapped. Hydroelectricity is not only the cheapest but also the cleanest and the most environment-friendly, and is thus the preferred source for power generation. The role being played by hydroelectricity in keeping the power tariff at present level can be measured from the fact that according to data for fiscal year 2013-14, per unit generation cost of hydroelectricity is merely Rs. 1.65 on an average as compared to Rs. 7.53 for gas, Rs. 11.66 for coal, Rs. 11.74 for bagasse, Rs. 18.68 for furnace oil, Rs. 28.41 for diesel (HSD), Rs. 6.38 for nuclear and Rs. 14.55 for wind.
Another reason why Pakistan needs to harness immense water potential relates to increasing water needs of the country. In the absence of sufficient number of water reservoirs, per capita water availability has decreased from 5620 cubic metres in 1950s to a little over 1000 cubic metres in 2014; thereby exposing the country to a prospect of being water-stressed.
Geographically, Pakistan is located in a zone that is likely to experience erratic weather patterns as a result of climate change. Consequently, the country will face worst floods caused by excessive glacier-melting and extreme drought. This dynamic makes it all the more compelling to focus on building new dams and water reservoirs to ensure water security for the country and to meet growing needs of its agriculture, industry and population.
Dams not only help store water for agriculture and inexpensive power generation but also play an important role in flood mitigation. Pakistan experienced one of the most devastating floods in 2010, which according to a study, jointly carried out by the World Bank and Asian Development Bank, caused a cumulative loss of $10 billion to economy besides loss of hundreds of precious lives.
As these lines are being written, flood caused by torrential rains and release of water by India has swept across Punjab and Azad Jammu & Kashmir. It is still too early to calculate the exact damage in man and material caused by the recent floods.
However, what is little known is the fact that Pakistan’s existing dams are serving as a shield against flood thereby reducing the ferocity of floodwater as it leaves destruction and miseries behind.
The study of raised Mangla Dam project presents a readily-available reference point in this respect. Mangla Dam was completed during 1962-67 as part of Indus Basin Treaty replacement works at a cost of $434.505 million. The original storage capacity of the dam was 5.88 million acre feet (MAF) of water. The vital components of the dam were main dam, intake embankment, Sukian Dyke, Jari dam, and other earth-fills to close gaps in reservoir rim.
With the passage of time, the total water storage capacity of Mangla dam reduced by 20% due to siltation. In order to fully utilize the Jhelum river water resources, it was considered necessary to increase the storage capacity of Mangla reservoir. So the work on Mangla Dam Raising Project was initiated in July 2004. The project was completed at a cost of Rs. 96.853 billion in December 2009 and affected about 50,000 people. The dam was raised by 30 feet up to 1242 feet with a gross storage capacity of 7.39 MAF representing an increase of 2.88 MAF.
Following successful completion of the Raising project in 2009, the impounding of reservoir took place, recording water storage of 1206 ft above mean sea level in 2010, 1210 ft in 2011, 1206 ft in 2012 and 1240 ft in 2013 respectively. This year, there is all likelihood that Mangla reservoir will achieve the historic feat of filling up to its maximum capacity of 1242 feet above mean sea level.
The level of Mangla reservoir prior to this year’s flood was 1227.80 feet above mean sea level on September 4, 2014. The WAPDA officials who were stationed at the site held their breath as floodwater entered the dam the same day making it attain 1241.15 feet. Engineers express their apprehensions about stability and safety of a dam when it is filled to its optimum capacity thereby confirming the strength of its structure to withstand rapid flows of water.
Now imagine for a moment, had there been no raised Mangla dam to trap much of the floodwater, about 391000 Cusecs of Jhelum water at Mangla would have combined with 102462 Cusecs of Chenab at Marala to record a cumulative 493462 Cusecs at Head Trimmu, which would have wreaked far greater havoc than what we are witnessing now. In the same way, heavy flood of 1004614 Cusecs would have invaded Head Trimmu after 634000 Cusecs of Jhelum at Mangla and 370614 Cusecs of Chenab at Marala had merged together in case of no Mangla dam being there to tame peak inflows.
Other benefits accruing from raised Mangla dam have been monetized to be well over Rs. 110 billion per annum in terms of enhanced agricultural production, additional electricity generation and mitigation of flood hazard. Additional 2.88 MAF of water, following completion of raised component of the project, will irrigate another 1.34 million acres of land and generate 644 million additional units of electricity per annum from existing Mangla Hydel Power Station.
Recurring floods are an eye-opener. They draw the attention of policymakers to the imperativeness of constructing more and more water reservoirs to augment our precious water resources, much of which are wasted into the sea downstream of Kotri in Sindh. Time to act is now.