People, Environment

Sedimentation Plaguing Chaharmahal Dams

Sedimentation in dams can be minimized with thorough feasibility studies.Sedimentation in dams can be minimized with thorough feasibility studies.

Sediments annually inflict around 640 trillion rials ($16.8 billion) in damage to concrete dams in Chaharmahal-Bakhtiari Province, said the head of the provincial office of the Forests, Range and Watershed Management Organization.

During a press conference on Saturday, Ali Mohammadi-Moqaddam added that conducting feasibility studies is key to preventing the recurrence of this problem.

"At the very least, they help minimize the damage," he was quoted as saying by ISNA.

A river can be considered a body of flowing sediments as much as one of flowing water. When river water collects behind a dam, sediments sink to the bottom of the reservoir.

As the sediments accumulate, the dam gradually loses its ability to store water for the purposes for which it was built. Every reservoir loses storage to sedimentation although the rate at which this happens varies widely.

In 1996, Patrick McCully, an expert on dams, wrote in his book Silenced Rivers: "Despite more than six decades of research, sedimentation is still probably the most serious technical problem faced by the dam industry." The statement continues to be true to this day.

Chaharmahal-Bakhtiari has 16 dams, only a small number of which are made of concrete, including Khorasan 1 and 2, as well as Bazof dams. All three suffer from severe sedimentation.

The province, spread over 16,332 square kilometers, has a population of 900,000, a majority of whom work in the agricultural and livestock breeding sectors.

Although the implementation of large industrial projects in the province is helping its development, it has unleashed a plethora of problems: air pollution, depleting water reserves, dust storms and soil erosion.

According to Mohammadi-Moqaddam, around 80% of the province's water needs are supplied from groundwater resources, which is worrying.

"This is while ideally we should be using these resources to meet 20% of our water demand," he added.

The province has been grappling with drought for nine years, thanks to declining precipitation, global warming and rising demand for water.

Ardeshir Nouriyan, an MP from Shahr-e Kord, the province’s capital, has been a vocal critic of what he calls the Energy Ministry’s “discriminatory measures” that have exacerbated the province’s water problems.

Referring to the Beheshtabad scheme that aims to transfer water from Chaharmahal-Bakhtiari to Isfahan, the MP said last year work on the project began despite the staunch opposition of environmental officials and experts about the impact of the plan on the province’s groundwater resources and aquifers.

“The lobbies were so powerful that even thorough studies by experts were not able to stop the project,” he said.

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