When it comes to public protests in Iran, the first thing that usually comes to mind is politics. These days, there is a new reason: water scarcity. If this situation does not improve, it could turn into a major source of violence and instability in the country. On at least one occasion this year, it already has.

In March, after a week of demonstrations, violent clashes erupted in the town of Varzaneh in Iran’s Esfahan province between protesters and security forces. The clashes led to dozens being injured and more being arrested. The cause was the government decision to divert water from Esfahan province to Yazd province. The protesters saw the move as unfair, as Esfahan province is experiencing a drought. Esfahan’s own famous Zayande Roud river has dried up. My father almost drowned swimming in this river during his teenage years in the 1940s. These days, the river is so dry that you can go horseback riding in the very same spot.

There have also been other demonstrations, albeit peaceful ones. Last week saw the third demonstration in two weeks in the city of Ahvaz. This time, the protesters were angry about the government decision to divert water to Esfahan’s Zayande Roud as well as Yazd and Qom from the Karoun river, which flows into Iran’s Khuzestan province.

There are two factors which could turn the water-scarcity problem into serious clashes and ultimately a domestic security threat.