“In the past, around 350 to 400 kilometers of rivers were dredged a year on average. That has now increased by about four times so far this year,” the Energy Ministry news portal Paven quoted Mohammadreza Haj Rasouliha as saying.
Dredging is the removal of sediments and debris from the bottom of lakes, rivers, harbors, and other water bodies. It is a routine necessity in waterways around the world because sedimentation—the natural process of sand and silt washing downstream—gradually fills channels and harbors.
During the past nine months, rivers in many provinces have been dredged including Khuzestan, Lorestan, Golestan, Kermanshah, West Azarbaijan, Kerman, Khorasan Razavi and Sistan-Baluchestan provinces among others, Financial Tribune reported.
In the next fiscal budget (March 2020-21), submitted recently by the government to parliament, about $20 million has been allocated for river engineering, which shows a three-fold increase compared to $6.15 million in this year’s budget bill.
River engineering helps in optimizing rivers’ numerous benefits while providing protection against flooding. It involves modifying the natural river conditions including, stabilization, bank revetments, dredging, diversions, cofferdams, channelization, levees and flood control works.
Khuzestan a Special Case
The primary aim of most dredging works is to reduce flooding and act as a flood management tool. Most importantly, this needs to be undertaken in southwest Khuzestan Province that was hit by floods in March and April.
Torrential rains in different parts of Khuzestan led to devastating floods forcing the evacuation of at least 35 villages.
Due to the extended deluge, Karun, Karkheh and Dez rivers burst their banks and inundated cities and villages in Ahvaz, Shush, Dasht-e Azadegan, Howeyzeh, Dezful and Shushtar.
Dredging also focuses on maintaining or increasing the depth of navigation channels, anchorages, or berthing areas to ensure the safe passage of boats and ships. Vessels require a certain amount of water depth to be able to float and not touch bottom.
It is undertaken also to reduce the exposure of fish, wildlife, and people to contaminants and to prevent the spread of contaminants to other areas of the water body. This environmental dredging is often necessary because sediments in and around cities and industrial areas are frequently contaminated with a variety of pollutants.
In July, delegations from Iran and Iraq met in Tehran and discussed the general framework of the arrangements for dredging and clean-up of Arvand Rud (aka Shatt al-Arab), a border river in Khuzestan.
Although dredging can help control floods, experts believe that using natural flood management techniques should be a focus of flood mitigation measures, and dredging should not be considered as the best solution to contain the floodwaters.
Creating upstream holding areas for water, restoring wetlands and putting up more flood barriers are ways to slow the flow of water that can prevent floods from racing downstream.