Water Resource Development 

Major Surface Water Development

The major surface water development in the country has been based on the use of river waters of the Indus and its tributaries. This development which dates back to the middle of the 19th century was based on diverting the natural river flows. Initially the diversion of high flows was attempted in inundation or seasonal canals, but with progressive weirs or barrages across the rivers by controlling the water levels, make it possible to utilize the low Rabi flows for perennial irrigation and also permitted the transfer of waters across and through other rivers to the distantly located irrigable lands. 

For sharing the international waters of the Indus and its tributaries, the Indus Water Treaty was signed with India in 1960, accordingly to which India acquired the exclusive right to the waters of three Indus tributaries Ravi, Beas and Sutlej, and the irrigation systems in Pakistan dependent on these rivers had to be fed by the Indus and its tributaries, the Jehlum and the Chenab, assigned to Pakistan. This required the construction, with donor support, of the Mangla Dam (reservoir live capacity (6.58 BCM (5.34 MAF), Tervela Dam  (reservoir live capacity 11.59 BCM (9.4 MAF), five barrages eight inter-river link canals, linking the rivers Indus, Jehlum Chenab, Ravi and Sutlej, a syphon under the Sutlej river and remodeling of some existing barrages and link canals. Although these works were regarded as replacement work they also incorporated certain development aspects.

Both the Mangla and Terbela Dams, apart from meeting the irrigation water requirements were used for power generation and presently have an installed capacity of 1000 MW and 3478 MW respectively. These two dams, and the Chashma Barrage in which a small storage element of 0.62 BCM (0.5 MAF) was built in, serve as storages for the inter-seasonal transfer of water for meeting the irrigation requirements during the low flow periods. The Chashma Barrage has also been utilized for power generation and presently a low-head hydro-power station with an installed capacity of 184 MW is under construction.   

Following the construction of the replacement work under the Indus Water Treaty, no significant development based on the waters of the Indus and its tributaries, has taken place except for the construction of new irrigation canal (CRBC) from the Chashma Barrage, which on completion would irrigate an area of 0.23 Mha 90.568 MA).

For improving the control over the river flows and for power generation, a major dam on the Indus downstream from Tarbela, was planned in 1984. This Dam would have provided a storage 7.52 BCM (6.1 MAF) and added 3600 MW of hydro-power to the generating capacity. The construction of this dam however could not be taken up due to the controversies surrounding its adverse impacts.  

The surface irrigation system which is now all weir controlled, covers the world's largest contiguous irrigated area. It comprises of three storage reservoir (Tarbela, Mangla and Chashma with total original live capacity of 18.80 BCM (15.24 MAF), 16 barrages, 12 inter river link canals, 2 syphons, 43 main canals and 134, 000 watercourses or farm channels. The total designed diversion capacity of main canal is 7,249 cumecs (256,000 cusecs).

These features provide an opportunity for managing the surace supplies and canal system. 

The irrigation system dependent as it is on the variable flows of the Indus and its tributaries, commands a gross irrigable area of 16.85 Mha (41.46 MA) of which 14 Mha (34.59MA) is culturable command area (CCA) to which water is allocated. The perennial canal supply is available to 8.6 Mha (21.25 MA) while the remaining area is entitled to irrigation supplies only during  the Kharif season. The annual canal diversions which were 82.65 BCM (67 MAF) at the time of independence in 1947 have increase to 104.86 BCM (85 MAF) in 1967 and to 128.29 BCM (104 MAF) in 1975 after the commissioning of Mangla. At present 130.76 BCM (106 MAF) water is diverted for irrigation purposes.