ISLAMABAD, Sept 18: The Mangla Dam’s reservoir is slowly ‘dying’ due to sedimentation, posing a serious threat to land and water resources in the Indus plain, one of the largest irrigation systems in the world, it is learnt.

At the same time, the development of infrastructure for the growing population and urbanisation has increased soil erosion in the region, shrinking the catchment area of the dam.

Informed sources told Dawn on Tuesday that the Water and Power Development Authority (Wapda) had approached the federal government to permit it to urgently undertake a water management programme “to save the Mangla Dam” for the sake of the national economy and the vital needs of water and power.

Wapda officials have informed the Planning Commission that the primary objective of the proposed project is to reduce the sediment load flowing into the Mangla reservoir so as to prolong its useful life through improved methods of land use techniques and implementation of water management practices in the catchment area.

They also apprised the Commission that due to the 2005 earthquake in the catchment zone of Mangla Dam, the area has become “greatly susceptible to erosion which is adversely affecting the storage capacity of the reservoir and ultimately the power generation and irrigation flow”. The contribution of landslides in the area towards sediment generation is also significant.

Wapda officials maintained that water management problems were of serious nature in view of the fast rate of siltation of the reservoirs. For agricultural production, they said, adequate and regular supply of water was essential and this largely depended upon the proper management of the reservoirs.

The AJK region is of mountainous nature where land-sliding is a permanent feature contributing maximum silt in the adjacent rivers which is directly carried out into Mangla reservoir and adversely affects the equilibrium of the ecosystem and also alters the regime of rivers falling into the reservoir.

Prior to filling of Mangla Dam, investigation carried out by different agencies in respect of the Jhelum river indicated that Mangla reservoir with its storage capacity of 5.88 million acre-feet (AF) would be receiving an annual sediment of 42,000 AF and will be silted up in short period of about 100-110 years. Thus, the serious erosive condition is posing a great threat not only to the useful life of the dam but also to the rivers and canals by way of raising their beds and causing floods, etc.“Conservation of this valuable national resource for a longer time is vital for feeding our irrigation system to meet future water requirements for agriculture, domestic and industrial use and generating,” Wapda officials told the Planning Commission, the details of which were also shared with Dawn.

These measures besides increasing life of Mangla Dam are substantially contributing towards improvement of socioeconomic conditions of the people living in the areas through increase in forest wealth, improved agriculture output and better environment.

Wapda officials quoted the report of their consultants that erosion siltation in the catchment area of Mangla Dam was of alarming nature and if this state of affair is allowed to persist Mangla reservoir would rapidly deplete its storage capacity.

It was, therefore, considered that comprehensive water management measures be taken in the catchment area of Mangla Dam to control the rate of soil erosion and inflow of sediment into the reservoir to prolong its life.

The catchment area of Jhelum river above Mangla covers about 12,870 square miles, out of which 56 per cent lies in the Indian-occupied territory of Kashmir and as such is not accessible to Pakistan for water management measures. Of the balance area of 44 per cent (5,710 sq miles) in Pakistan and the AJK 3,433 sq miles is the focus of the project operations. Rest of the areas are under roads, colonies, or forest lands the management of which is the responsibility of provincial departments.

Climatically the catchment area of Mangla Dam lies in the region of rapid transition. The main precipitation occurs in two seasons of the year — in monsoon from July to September and winter rains from December to March.