In the Himalayan region, sediment is  a structural component of river systems. The bed load transported downstream forms the material through which rivers regulate channel shape, dissipate energy, stabilise banks, recharge groundwater, and sustain floodplains. Fluvial geomorphology has long established that sediment load is integral to river equilibrium. When this material is extracted indiscriminately, rivers are forced out of balance, often producing impacts more damaging and persistent than the floods or siltation that mining is meant to address.

At the heart of river stability lies the  concept of distribution of shear stress along the channel bed and banks. Even modest increases in shear stress beyond  threshold level can mobilise large particles, propagate erosion upstream and downstream, and undermine structures thought to be safely outside the mining zone. Understanding and regulating shear stress distribution is therefore not only an academic exercise, but central to predicting whether a river will adjust benignly or degrade aggressively in response to intervention.

This understanding has gained urgency as desilting and riverbed mining have expanded rapidly across the  Himalaya, including Jammu and Kashmir. The stated objectives; flood mitigation, increased channel capacity, and meeting construction demand, are familiar. However, scientific research on mountain rivers consistently shows that poorly regulated sediment extraction frequently undermines these very goals.

The problem of ‘hungry water’

One of the most widely cited phrases  in river science is that of “hungry water.” According to a seminal 1997 paper by geomorphologist Grant Kondolf in Environmental Management, when sediment is removed faster than it can be naturally replenished, flowing water becomes sediment-starved and regains excess erosive energy. This “hungry” flow begins........

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