Is former Member of Punjab Public Service Commission
A farmer and keen observer of current affairs
When The Tribune reported that Gobind Sagar’s storage has fallen and suggested desilting as a cure, the headline tugged at a familiar hope: fix the reservoir and the problem is solved. But headlines that ring well in a studio do not make them engineering or economic truths. Seen through a global lens, two things are clear: reservoir siltation is real and widespread — and full desilting of very large dams is rarely a realistic option.
First: the scale. Reservoirs worldwide lose meaningful storage to sediment every year; managers estimate substantial capacity declines in many mid-century reservoirs and predict increases unless catchments are controlled. Independent research shows the problem is not local. United Nations University / UN research and related studies estimate that trapped sediment has already robbed roughly 50,000 large dams worldwide of about 13–19% of their original combined storage, and that losses may rise to about 23–28% by 2050 if nothing changes. Some high-profile storage projects (Tarbela, Mangla and others) have experienced decades of serious sedimentation and have been the subject of flushing, bypassing and partial measures — not full dredging. Full, reservoir-wide dredging at a Bhakra/Tarbela scale is effectively unheard of because of sheer logistics.
Second: the money. Dredging costs vary, but standard engineering estimates put common hydraulic dredging in the costs very heavy on per cubic metre, and complex projects many times that. Translate that into the hundreds of millions — or billions — of cubic metres of silt trapped behind a giant dam and the arithmetic becomes brutal. Conservative, back-of-the-envelope calculations for very large reservoirs show costs running into many billions of dollars — sums that dwarf conventional repair budgets and far exceed simple “sell the sand” schemes.
Third: the material. Not all dredged material is sand ready for road making. Dredged sediments are often fine, water-logged, compressible and poor in shear strength; many geotechnical studies caution that without treatment (blending, drying, stabilisers) such material is unsuitable for structural fill — especially for engineered mountain roads that demand compacted, well-graded fill and predictable behaviour under load. Some small reservoirs have had successful, local desilting with part of the material reused after conditioning; these are not scalable models for a Bhakra-scale operation.
Fourth: hill roads and tunnels involve hill cutting and generate lot of muck. Road building in steep, geologically sensitive hills commonly requires controlled quarry rock, graded fill and engineered retaining — not a slurry of lake silt. Tunnel construction produces rock and broken mass (hard, coarse spoil) — a very different material from soft reservoir sediment — and tunnel projects struggle to find legal, ecological and social avenues for spoil disposal. Re-using tunnel muck and reservoir silt are separate technical problems; conflating them is sloppy policy.
Finally: disposal logistics. Even if silt could be made usable, where would billions of cubic metres go? Confined disposal sites, drying basins, transportation corridors and markets must be secured — each a major civil project in itself. Selling sand locally might offset a fraction of costs for small-scale projects (and there are Indian and international examples of such pilots), but importing the cost of moving millions of truckloads uphill or from a mountain reservoir to distant plains is an economic fantasy.
Practical evidence shows there is no ready precedent for full desilting of mega reservoirs. What we find instead are targeted, small-to-medium dredging projects and operational fixes — for example, the U.S. Bureau of Reclamation’s removal of sediment upstream of Imperial Dam and the mechanical dredging of Cogswell Reservoir — both substantial but tiny compared with Bhakra’s scale. Large projects such as Tarbela and Mangla have relied on flushing, bypass and supplementary works rather than wholesale dredging because full-scale sediment removal is usually logistically immense, environmentally fraught and economically ruinous. Flushing is normally done in case of tunnels of Run of river projects. In short, “let’s desilt and sell the silt for road-making” sounds neat in a press note; in engineering practice for a Bhakra-scale reservoir it is, to put it bluntly, a mirage.
So what should honest policy look like? Stop promising full desilting for giant reservoirs without transparent feasibility studies. Prioritise catchment treatment, silt-bypass works for new projects, selective pilot desilting where material is marketable and environmental safeguards are in place, and clear reservoir audits so interventions are ranked by cost–benefit. If politicians want to be serious, fund engineering studies not slogans — and make the arithmetic public.
Bhakra’s loss of capacity is a real problem; pretending that full desilting is an easy, cheap fix is not just unhelpful — it is misleading. Let us shift the debate from platitudes to practicable engineering, honest costings and prevention upstream. Only then will we have policies that actually restore water security rather than stage a mirage.
Real solution lies elsewhere: Reforestation to arrest erosion and landslides.