Punjab’s recurring floods call for urgent dam reforms

PUNJAB has faced devastating floods this year for the fifth time since 1988 — after 1993, 2008, 2019 and 2023. Incidentally, only the Sutlej and Beas rivers have been responsible for these floods.

The Ravi was in a furious mode only this year. The pattern of occurrence of floods was more or less familiar every time. There were incessant rains in the Sutlej and Beas catchment areas in the last week of August and first two weeks of September when the reservoirs of two dams were already full to the permissible levels. Consequently, water had to be compulsorily released in sufficient quantities from the spillways to keep the reservoirs at safe optimum levels.

This flow, together with the flow generated by the sub-hilly regions lying downstream of the two dams, swelled the two rivers that moved further by breaching the weak embankments in the way, inundating a large number of villages.

This time, the catastrophic floods were caused by heavy rains more in the sub-hilly regions than in the catchment areas of the three rivers and the flow generated downstream of the dams was in lakhs of cusecs. For example, till September 7, the BBMB released only a limited flow that was just enough to run the power plants at their rated capacities.

The flow in the Sutlej and Beas rivers was almost entirely due to the copious discharge brought by the tributaries and streams joining the two rivers downstream of the dams. For example, there are 16 streams, including the two big tributaries of Swan and Sirs, that merge into the Sutlej between the Nangal dam and the Ropar headworks and the combined flow of these 16 streams was more than 3 lakh cusecs.

The flow pattern in the Ravi was slightly different. Here, unlike the BBMB, the Irrigation Department of Punjab did not reveal the figures of inflow and outflow in respect of the Ranjit Sagar reservoir.

There is a possibility that more discharge was released from the spillway than required for running the 600-MW power plant. This is because the live storage capacity of the Ranjit Sagar reservoir is only 2.33 billion cubic metres, that is, 30% of the Pong Dam reservoir and 38% of the Bhakra reservoir. Also, the surface areas of Ranjit Sagar, Pong Dam and Bhakra Dam reservoirs are 52 sq km, 241 sq km and 168 sq km, respectively.

Thus, because of the smaller size of the reservoir, the Ranjit Sagar dam is unable to hold large inflows or moderate peak flows. This is another reason for the unprecedented discharge of 4 lakh cusecs in the Ravi.

There is another 121-mt high Chimera dam in the upstream across the Ravi near Dalhousie. The volume of its storage space is about 0.45 billion cubic metres (bcm). Similarly, the 167-mt high Kol dam upstream of the Bhakra Dam occupies 0.6 bcm of storage space.

Unfortunately, the two dams have been designed as run-of-the-river projects. Their reservoirs are kept full round the year to generate maximum electrical energy. Had the two been designed as storage dams, their reservoirs could have provided the necessary cushion to hold large inflows during the critical periods and moderate the peak flows over the spillways of Ranjit Sagar and Bhakra dams.

Looking at the frightening inundation in 2,000 villages across eight districts and the consequent destruction of rural economy, both Punjab and Central governments need to take urgent measures to prevent such catastrophic floods in future. Some measures are detailed below.

Short-term measures

1) In conformity with rainfall forecasts by the IMD, the BBMB should keep the reservoir level in the two dams at least one metre less than the full reservoir level (FRL) around August 20 so that more inflow can be accommodated during the critical period of August-end to early September. A similar policy should be followed by the engineering wing of the Ranjit Sagar dam.

2) The waterways under all bridges must be fully cleared of the silt deposited during the preceding year. Likewise, the gates of all weirs and barrages must be checked for their functionality before the onset of the rainy season. It is learnt that only five gates of the Madhopur headworks could be lifted as the others were stuck in slush and debris.

3) The Irrigation Department must ensure that each of the three rivers is able to carry a safe discharge of 4.5 lakh cusecs.

This is possible only if the department strengthens the existing vulnerable embankments, closes the gaps where the embankments have been breached by mining contractors, provides marginal embankments and builds spurs and groins at critical points of embankments throughout the course of the rivers. This job should be completed before the onset of the rainy season next year.

4) River training works should be provided along the Sutlej in the 53-km stretch between the Harike and Hussainiwallah barrages to enable the river to safely carry the combined flow of the Sutlej and Beas rivers.

Long-term measures

1) The Punjab Government should make earnest efforts to build a storage dam of 1-bcm capacity by reviving the Khab project across the Sutlej upstream of Reckong Peo. The storage at this dam will absorb flash floods and facilitate in-flood routing at the Bhakra reservoir. It will also immensely help in augmenting the generation capacity of all hydroelectric power projects across river in the downstream.

2) The scope for building a similar storage dam in the catchment area of Beas river is limited. But some silt-retaining dams of lesser heights must be built because the siltation problem in both Pandoh and Pong dams is a matter of serious concern.

3) The scope for building storage dams across some tributaries in the catchment area of the Ravi is much brighter. The valley there is a fit case for developing additional water resources and preventing floods on the lines of the steps taken by the Damodar River Valley Corporation.

Four dams were built across the Damodar river and its two major tributaries between 1951 and 1959 to prevent floods in Hoogly, Bardhwan and Howrah districts of West Bengal. At present, the Ranjit Sagar dam is unable to handle large inflows due to its small-sized reservoir.

4) An aggressive programme should be launched to build water-harvesting structures in the sub-hilly areas downstream of the three dams to tame tributaries such as the Swan, Sirsa, Chakki, Kali Bein, Ujh and Siswan. Some of them carry discharges as high as 70,000 cusecs at times.

These measures can prevent the recurrence of devastating floods in Punjab. There is no shortcut to achieve this objective.

RN Malik  is retired Engineer-in-Chief, Public Health Dept, Haryana.