IIn recent decades, there has been a dramatic increase in the number of dams being built to keep up with the demand for water or to provide power. Concerns have been raised about increased landslide activity near new dams, and now a study has shown a conclusive link in at least one incident.
In March 2019, a landslide tore apart Hoseynabad-e Kalpush village in north-central Iran300 houses damaged and the road to the nearby dam cut off. Local authorities blamed the landslide on heavy rainfall and maintained that the dam did not play a role.
However, scientists from the German Research Center for Geosciences in Potsdam studying satellite data from this region showed that this previously stable slope began to move after the reservoir began to fill with water, in 2013. The findings, published in Engineering Geologyshows that the land movement initially started from the lower part of the slope in 2015 and gradually progressed upwards in the following years, as the reservoir water level increased.
Results indicate that the accumulation of water in the dam raised the local water table, making the ground in the nearby hillside more mobile, eventually reactivating an old landslide. Exceptionally heavy rainfall in early 2019 provided the final trigger for the landslide. This is a cautionary tale and a risk that dam engineers must consider.
