Dam constriction on Anzali wetland; threats and advantages

May 18, 2019

TEHRAN – With the construction project of Lasak dam on Anzali wetland getting underway many are now voicing concerns or counting advantages of building the dam on the precious ecosystem.

Following the construction of a dam in Gilan province, Anzali wetland may bear dire consequences, Masoud Baqerzadeh Karimi, the director general of aquatic ecosystems at the Department of Environment (DOE) has said.

Covering more than 19,000 hectares, the wetland is located near the northern port city of Bandar Anzali, neighboring the Caspian Sea. The wetland was designated as a Ramsar site on June 23, 1975. It is fed by several rivers and separated from the Caspian Sea by a dune system. The lagoon is home to submerged and floating vegetation and also extensive reed beds. It bears international importance in terms of breeding, staging and wintering water birds.

Lasak dam prevents the entry of spring floods into the wetland, which results in accumulation of sediment, and finally water level reduction, he lamented.

The wetland is already suffering huge sediment loads accumulated on its bed which causes the wetland to loose part of its retaining capacity, he stated, adding, so, the wetland is not able to retain water and the water constantly enters the sea.

Lasak dam prevents the entry of spring floods into the wetland, which results in accumulation of sediment, and finally water level reduction

In such condition, dam construction only compounds the situation, when the wetland already must be revived reducing sediment loads and expanding its capacity, he further said.

He went on to explain that obviously, the dam acts like a barrier preventing spring floods into the wetland, which can move the sediments and contaminants to enter the sea; although pushing the pollution to the sea is not a good idea, it prevents the accumulation and concentration of contaminants in the wetland.

Dam construction is in contrast with wetland conservation, restoration means increasing the wetland’s reservoir volume, on the other hand, dam prevents the water to enter the wetland, so, if the wetland capacity expand, there will be no water to fill it, he also explained.

At least an important point must be considered in damming, which is granting the wetland’s water right, he highlighted, adding so, environmental assessment prior to construction is a must.

Elsewhere in his remarks, he stated that economic activities, such as tourism, fishing and sailing, also depend on the depth of the wetland, adding, some species of migratory birds wintering in the Anzali wetland choose its deepest areas as habitats for food supplies, therefore, it will greatly affect the area’s biodiversity.

Deputy environment chief Masoud Tajrishi also said that Lasak dam will surely bring environmental consequences, but it has a 4 percent effect on the inflow of Anzali wetland.

Referring to the dam as a source of fresh water supply, he said that unfortunately, due to excessive use of fertilizers and chemical pesticides, groundwater resources of the provinces of Gilan and Mazandaran are polluted and the dam’s water must not be used for drinking purposes.

This is while, Vahid Khorrami, Gilan’s regional water company director, said that the dam has a positive effect on the reduction of Anzali wetland’s sediments.

One of the objectives of constructing the Lasak dam is reducing the sediments, which are continuously entering the wetland even when there is no dam near it, he said, adding, so the dam will help the wetland to get rid of the sediment loads.

Over 2.3 billion cubic meters of water enter Anzali wetland, and the Lasak dam retain only 45 million cubic meters of water, of which, 33 million cubic meters will be released as the water right of the wetland, he explained.

He went on to conclude that the flood will be restricted by the dam, therefore, it will help reduce the accumulation of sediments in the wetland.

In early January Mehdi Abtahi director of Isfahan Science and Technology Town said that amid all the contaminations increasing in the wetland for a long period of time, minerals play a major role in causing severe threats to the regions biodiversity, thus the wetland undergone numerous environmental problems.

A scheme on restoration of the endangered Anzali wetland by removing contaminants using domestic bioremediation nano-technology will be implemented, which is earmarked a total budget of 9 trillion rials (nearly $215 million), he added.

The scheme was proposed by researchers at Isfahan Science and Technology Town and approved by the DOE.

FB/MQ/MG

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