Following severe flooding last week that left a trail of destruction in nine provinces in western and southwestern Iran, advocates of dam construction wasted little time to sing the praises of the gigantic barriers that they claim help mitigate damages caused by flooding.
However, environmental experts say that simply could not be further from the truth.
According to scientists, including Mohammad Darvish, a researcher at the Research Institute for Forests and Range, proper management would have ensured the floods inflicted minimal damage and, more importantly, be used to restore drying wetlands and submerge the sources of dust storms in water.
“Nowhere in the world do they use dams to control floods; it’s just unheard of,” Darvish, who also heads the Public Participation Office at the Department of Environment, told Mehr News Agency. “Flood management has its own protocols.”
Maintaining vegetation, banning construction along rivers and managing watersheds are but a handful of ways to reduce the impact of flooding, he said.
Located in an arid and semi-arid region, Iran is prone to flash floods due to a lack of sufficient vegetation, which makes efficient flood management all the more imperative.
What Could Have Been
Proper water management could have turned the natural calamity that befell a third of the country into a potential solution for the rampant dust storms that hit the flood-hit regions frequently.
“We can create paths to divert flood waters to wetlands on the brink of desiccation and regions that contribute to dust storms,” said Hamidreza Khodabakhshi, head of the Waster Engineers Syndicate.
Furthermore, surface runoff is rich in nutrients, which can nourish regions that do not have fertile soil.
“Plains in Khuzestan, Fars and Kerman provinces have historically been prime agriculture regions,” Darvish said. Despite their unfavorable climate for farming, those provinces were at one point top farming regions, but no more.
“A long time ago, flood waters kept the soil in those provinces fertile, but ever since we started damming rivers in those regions, farming began to decline,” Darvish said.
Land Use Change
Flooding is a natural process that helps maintain ecosystem composition and processes, but can be altered by land use changes, such as dam construction and deforestation.
“Vegetation, especially trees, helps prevent what is known as splash erosion,” Darvish told IRNA. Splash erosion results from the bombardment of soil surfaces by rain drops, which act much like little bombs when they fall on exposed or bare soil. They detach soil particles and destroy soil structure.
Raindrop impacts break up clumps of soil. The lighter materials — such as fine sand, silt, clay and organic material — that are detached by raindrop are more readily carried away by runoff, leaving behind larger sand grains, pebbles and gravel. In other words, not only does a lack of vegetation exacerbate the impact of flood downstream, but also results in the erosion of soil upstream which takes a toll on farming.
Vegetation help prevent splash erosion by breaking the fall of raindrops, allowing the soil to absorb rainwater.
Watch Out for Profiteers
Never among those who mince words, Darvish said engineering firms in big numbers are trying “to take undue advantage of the recent flooding” to convince people that the construction of more dams will help mitigate flood damage.
“That’s utterly false and we can’t afford to let them seize this opportunity,” he said. “They obviously profit from building more dams… we shouldn’t be taken in by their sales pitch.”
Damage caused by flash floods can be mitigated by restoring vegetation and managing watersheds, the researcher was quoted as saying.
