BARCELONA — Drainage of peatlands to cultivate oil palm in Malaysia’s Rajang Delta is causing land subsidence that will bring large-scale floods in coming decades, making the land unusable, a problem also expected to affect Indonesia, researchers warned.
Substantial areas of the river delta in Sarawak, eastern Malaysia, are already experiencing drainage problems, according to a study commissioned by Wetlands International, a Netherlands-based conservation group.
It predicted that 42 percent of the 850,000 hectares of coastal peatland would experience flooding in 25 years, rising to around 82 percent in 100 years.
The cause is massive conversion of peat swamp forests to agriculture, mainly oil palm plantations, with only 16 percent of Sarawak’s natural peat forests remaining, said the study by research institute Deltares.
Wetlands International urged governments and businesses to stop the conversion of peat forests to agricultural or other use immediately, and promote peatland conservation and restoration.
“Current trends whereby vast areas of peatlands are opened up for drainage-based activities will render these areas unproductive and useless, and this will adversely impact communities, industries and biodiversity that rely on such areas for their very survival and existence,” Lee Shin Shin, a technical officer with Wetlands International in Malaysia, said in a statement.
A growing number of multinational companies involved in the production, trade and use of palm oil—a cheap, edible oil—have promised not to develop oil palm plantations on peatlands, but the impact of those fledgling commitments remains unclear.
Peat soils are made up of 10 percent accumulated organic material (carbon) and 90 percent water. When water is drained from the soil, the carbon in it is turned into carbon dioxide and the climate-changing gas is emitted into the atmosphere.
The carbon loss reduces the peat volume and causes the soil to subside until it reaches sea or river levels, leading to flooding, Wetlands International said.
Nyoman Suryadiputra, director of the group’s Indonesia office, said the study results were relevant to Indonesia, which is experiencing the same patterns of peat swamp forest loss for oil palm and Acacia planting for pulp wood plantations.
“Thousands of square kilometers in Sumatra and Kalimantan may become flooded in the same way as the Rajang Delta, affecting millions of people who depend on these areas for their livelihoods,” he said.
Wetlands International said measures used in developed countries to cope with soil subsidence, such as building dikes, were too costly and impractical for the two Southeast Asian nations, with their rural economies covering thousands of kilometers of coastline and rivers, and intense tropical rainfall.
But there are many crops that can be cultivated on peatlands without drainage, including more than 200 commercial local peat forest tree species such as Tengkawang, which yields an edible oil, and latex-producing Jelutung, Wetlands International said.
These could provide alternative, sustainable livelihood opportunities for local communities, but varieties would need to be improved and tested before they could be used on industrial plantations, it added.
