1. The dam should be treated with the utmost concern. A dam of probably somewhat smaller dimensions in 1858 filled and failed catastrophically leading to a flood wave that caused immense damage — the second largest on record for the Upper Indus – reported to have had an 18m peak at Attock, probably more than 20 m at Chilas, and likely 10-15 m at Tarbela, scouring and carrying immense volumes of sediment.
2. However, in the Atabad section there are also several prehistoric megaslides which once blocked the Hunza and remained stable dams for decades or centuries. Obviously they inundated land that is today inhabited or carrying the KKH. It depends upon the nature and composition of the landslide whether it has to be treated as stable or unstable. It is, of course, a serious geotechnical problem requiring experienced engineers to determine whether a spillway can be constructed safely and in time, whether a permanent lake at some level could be stable and acceptable — possibly beneficial?? Careful monitoring is essential to identify whether water quickly finds ways to seep through the landslide (piping), or if it seems well-sealed.
3. I will be happy to provide interested parties with the historical documentation and my own studies of the landslides and outburst floods, that may help in deciding what to do.
3. However, let me add, people first! The people in the area of the landslides and up-valley need urgent assistance. Since it is mid-winter time there are prospects of further snow and intense cold I would urge the authorities to act quickly to ensure food, fuel, medical supplies and, if needed, temporary shelter, reach the areas at and above the landslide.
Dr. Kenneth HEWITT
Department of Geography and Environmental Studies,
Research associate, Cold Regions Research Centre,
Wilfrid Laurier University, Waterloo, Ontario, N2L 3Z9