Check dams need review
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Check dams need review

While the government continues to promote check dams as a way to improve the nation's water management mechanism, little attention has been paid to the adverse impact such structures may have on the surrounding environment.

Check dams--small weirs built to slow the current along a waterway to reduce soil erosion and improve water retention--may seem environmentally friendly, but an increasing number of environmentalists are becoming concerned by their impact on the ecology of forests, which are crucial in the fight to slow global warming. Despite the growing evidence pointing towards their negative impact on ecologically sensitive areas, the government looks set to continue building such structures. This is a travesty.

Environmental activists breathed a sigh of relief when the Parliament shot down the Interior Ministry's budget proposal to fund its plan to build several soil-cement check dams across the country. Had the scheme sailed through, many check dams would have been built in watershed areas located in pristine forests, which could harm rather than help the environment.

However, the threat remains because the Ministry of Natural Resources and Environment (MNRE) -- which is supposed to be the guardian of the nation's forests -- is the primary supporter of the scheme.

At the heart of the problem is the authorities' unquestioning belief in the benefits of check dams for the forest. They believe check dams should be built because, theoretically, they help improve water retention, prevent forest fires, and keep erosion in check.

The latest proposal to build check dams by the MNRE would see over 600 such structures built in the watershed area in Mae Sa, Chiang Mai. These dams would be built inside national parks and forest reserves to help ensure continuous water flow into the Mae Kha canal in downtown Chiang Mai, which authorities are promoting as a tourist attraction.

The fact that authorities are choosing to overlook forest ecology for the sake of tourism is truly worrying.

Check dams gained popularity after they were promoted through various royal initiatives. These initiatives sought to emulate indigenous practices of using natural materials to build small dams along creeks -- a grassroots approach that caters to specific local geography and needs.

However, businesses have exploited this approach. Plastic, tyres, and concrete have replaced natural materials in the construction of check dams, leading to severe pollution when the materials decay and disintegrate. Past schemes to build check dams also failed to heed the concerns of local residents.

In addition, many were built without any environmental impact assessment.

More recent studies have shown that check dams prevent fish migration, affect water quality and cause biodiversity to decline in some areas. Check dams also disrupt the natural flow of sediment from a river's headwater, depriving downstream areas of natural fertiliser.

While check dams may be beneficial in drought-hit areas, they are certainly not needed in parks and forest reserves, where the priority is the preservation of biodiversity.

Forest authorities must stop recklessly promoting check dams. Instead, they should focus their attention on sustainable solutions.

Last but not least, they must be made legally accountable for breaking their own laws on environmental protection.


Bangkok Post editorial column

These editorials represent Bangkok Post thoughts about current issues and situations.

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