Tarbela brims over, Mangla falls short

LAHORE: Tarbela Dam has reached full capacity following prolonged high flows in the Indus River, while Mangla reservoir—though augmented to a reasonable level by a late influx from the Jhelum River—remains about one-fourth below its maximum conservation capacity.

According to a spokesperson for the Water and Power Development Authority (WAPDA), Tarbela Dam attained its maximum conservation level of 1,550 feet above mean sea level on Thursday, with 5.728 million acre-feet (MAF) of live water storage. The filling of Tarbela to its peak level is a positive sign for irrigated agriculture and hydropower generation in the country.

For the past 50 years, Tarbela Dam has played a pivotal role in Pakistan’s socio-economic development by supplying water for agriculture when required, controlling floods, and generating low-cost hydropower.

The high water levels at Tarbela have been attributed to widespread monsoon rains in northern Pakistan and Glacial Lake Outburst Flood (GLOF) events in Gilgit-Baltistan, which have contributed significantly to the Indus River and its upper tributaries. Experts said that these ample water reserves are expected to support crops in the upcoming Rabi season.

However, Mangla Dam—the country’s largest reservoir—remains a source of concern. Against its full conservation capacity of 7.25 MAF, the current storage stands at 5.423 MAF, or 74.52 percent, with a water level of 1,217.45 feet compared to its maximum 1,242 feet.

The filling pattern at Mangla, on the Jhelum River, mirrors that of India’s dams on the Ravi, Beas, and Sutlej rivers, including Thein, Pong, and Bhakra, none of which have reached full capacity according to recent data.

In contrast, Tarbela on the Indus has not only reached full capacity despite several drawdowns due to heavy inflows but has also contributed significant downstream outflows—releasing around 10 MAF of water into the Arabian Sea via the Indus Delta.

This underscores the urgent need to enhance storage capacity on the main Indus River, particularly in view of climate change-induced flow variability. Expanding storage would optimise water resource management and substantially mitigate flood impacts.

With further rain spells predicted in the coming days, it is likely that Mangla’s storage will improve, while additional volumes from the Indus may continue draining into the sea. Estimates suggest that outflows into the sea during the remaining Kharif season could surpass the storage levels of the major dams.