Conservation of Surface Water in Pakistan-The Controversy of Kalabagh vs Basha Dam

Despite the fact that Pakistan’s economy is so heavily dependent on agricultural produce, contribution to her GDP from his sector has been steadily declining from over 35% in 1970’s to 24% at present. This has been partly attributed to deficit water availability. The Tarbela reservoir was commissioned in 1974 with a gross storage of 11.62 million acre feet (MAF) but now its live storage capacity is just 8.21 MAF. The Warsak reservoir has completely silted up, while Mangla and Chashma storages have also depleted by 1MAF. Thus our storage capacity has consequently fallen by about 2.5MAF so far and if we didn’t add to our existing facilities, we will soon be faced with acute shortage of irrigation water and hence, decline in crop yield. Increasing population and high demand for more food requires vertical and lateral increase in agricultural productivity, which can only be achieved by conserving surface water and its judicious use. In fact not only the lost reservoir space has to be reclaimed but new storages must be built to preserve the 85% discharge available in summer.

Records shows that mean annual runoff of the Indus river at Basha has been 50 MAF while at Kalabagh it has been about 90 MAF. Downstream Kalabagh the Indus is joined by the Jhelum and Chenab rivers thereby increasing its total volume to about 147 MAF, annually. Presently about 104 MAF is utilized for irrigation through canals while the remaining 33 MAF is discharged to the Arabian Sea sownstream Kotri. According to the revised design, the Kalabagh dam will store 6.1 MAF of water and pose little threat to Sindh and Balochistan because there will still be a balance outflow of 84 MAF annually available downstream Kalabagh whereas, the water of Jhelum and Chenab rivers will continue unchanged. Thus the interests of lower reparians would not be sacrificed but instead it would only reduce the water discharged downstream Kotri to the sea. The option of Basha dam instead of Kalabagh is not right in terms of conservation of surface water as the available volume at Basha is about 50% less than that available at Kalabagh. It would severely affect the inflow into Tarbela reservoir, particularly during the low discharge months of winter. Besides, it would not be possible to draw canals from the reservoirs because of its location and terrain. Thus Basha or Kachura dams can be accepted as additional reservoirs but not as an alternative to the Kalabagh dam.

In view of the ever increasing demand for higher crop yield and cheap electricity, the construction of new dams has attained urgent national priority. The construction of Kalabagh dam is, therefore, a matter of national interest and must be undertaken without further delay.          

Author(s):
S. Shafiqur Rehman
Department of Geology, University of Peshawar, Peshawar.