Pakistan: Depleting aquifers in Balochistan

Dawn, By Dr Muhammad Akram Kahlown

At present, about one-third of the world's population is facing water scarcity. Pakistan once a water surplus country is now facing severe water shortage. The per capita water availability is reduced from 5600 cubic meter to 1100 cubic meter over the last 55 years.

The recent extended drought has further aggravated the situation of water availability as well as its quality. Since Balochistan lies in arid to hyper arid region, beyond the moonsonal belt, it is, therefore, always more vulnerable to droughts.

Balochistan is the largest province which constitutes 44 per cent of the total area of Pakistan, hosting 5.7 per cent of total population. However, out of total 19.4 million hectares, only 2.07 million hectares are being cultivated due to shortage of water. Its population is about 7.5 million which will grow up to 9 million in the year 2010. Its water resources however are extremely limited as compared to other parts of the country.

The domestic water demand which was 25 million cubic meter in 1950 has now increased to 395 million cubic meter and would be about 525 million cubic meter by the year 2010. However, the increase in demand for agriculture and industrial supplies is much higher than its availability at present. The recent prolonged drought has further exerted pressure on the already dwindling natural water resources such as karezes, springs and seasonal water channels.

The groundwater is the only dependable source of water. However, continuous pumping of groundwater to meet the increased demands of agriculture, industry and domestic use has caused the problems of groundwater depletion and water quality deterioration. Now with reduction in rainfall and snowfall due to climate change, and of electric driven deep wells, the water table has fallen at an alarming rate. During the last two decades, the number of tube-wells has increased from 7,000 to over 22,000.

The area irrigated by tube-wells has also increased from 0.05 to 0.25 million hectares. Although the tube-wells brought many difficult areas under plough which were otherwise lying barren, but it has affected the groundwater levels resulting in drying up of many karezes and dug wells. In and around Quetta valley, which is very much influenced by this phenomenon, one can hardly see a karez flowing.

Similar is the position in other parts of Balochistan. Investigations carried out before the drought show that 2 out of 14 basins (Pishin Lora and Nari) are completely exhausted, whereas 6 out of the 12 remaining basins have used more than 80 per cent of their water resources. In other basins the water table is falling rapidly. This shows that there is an urgent need to undertake measures to rejuvenate the depleting aquifers.

How can we do this? We all know that the only source of water in Balochistan is rainfall and snowmelts, which by the way is adequate.

We need to utilize the flash floods by rainwater harvesting for recharging the groundwater and managing the watersheds. Rainwater harvesting is not new to Balochistan. This has been done by constructing over 160 delay action dams in Balochistan.

These delay action dams have some limitations, siltation is the most important one. In order to over come the problem of siltation in delay action dams, and hence to increase their recharging capability, the concept of leaky dam is introduced for the first time in Balochistan at Margat, 40 km from Quetta.

The leaky dam allows gradual release of water to enhance the recharge to groundwater. The measurements conducted on the effectiveness of leaky dam at Margat have shown 1 to 3 feet increase in water levels immediately after rain. Experiments initiated at this site to improve watershed conditions to reduce silt generation have shown promising results.

During the last two years, the ministry of science and technology has approved projects focusing on rainwater harvesting, evaluation of innovative, low cost interventions for recharging depleting aquifers, introduction of high efficiency irrigation systems and upgradation of labs and libraries.

With the approval of these projects, the Pakistan Council of Research in Water Resources has developed capabilities to undertake groundwater availability surveys, manufacturing and installation of low cost high efficiency irrigation system, provide advisory services on when to irrigate and how much to apply.

The PCRWR has also established a water quality testing lab at Quetta, which is being furnished with the state of the art equipment. These services are now available at nominal rates.

The PCRWR has also enlarged its water quality monitoring network in Balochistan. Earlier four cities namely, Quetta, Khuzdar, Ziarat and Loralai were in the net-work. Now four more cities have also been included in the programme. Under this programme water quality assessment is made once a year before monsoon.