Photo: ©KAS Thailand/Pattravut Boonprasert

The Lower Songkhram River from the Air

NOVEMBER 7, 2021

Running over 400 kilometres through the upper Northeastern region, the Songkhram River is the Mekong’s tributary and contributes around 1.8% of average annual water flows to the Mekong River at Tha Uthen district in Nakhon Phanom province.

Formed geographically as a vast flood plain, approximately 54% of the overall Songkhram Basin, which is the second largest basin of the Northeast with the total area sized around 6,473 square kilometres or around four million rai, could be classified as “wetlands”. The most extensive area, as noted by the Ramsar Site Information Service, is concentrated in the lowland floodplains of the lower section of the river.

Every year, the Mekong’s backflow intrudes the Lower Songkhram River during the peak flooding period from July to late September. Around 80,000 to 96,000 hectares (ha) of the lower section (500,000 to 600,000 rai) are flooded. It is reported to travel as far as 300 kilometres inland during some flooding years. Such a rare and unique phenomenon also occurs at Tonle Sap in Cambodia.

This “flood pulse” phenomenon contributes to complex water-based geographical characters, ranging from permanent and temporary surface water sources, artificial and natural wetland habitats, and a range of riverine, floodplain, lacustrine, palustrine, and salt-water wetlands.

According to Ramsar, the forest structure of the lower section of the river differs with the changing condition of the terrain. There are two sub-plant communities: pond vegetation and lowland floodplain forest. The terrestrial plant varieties found in the floodplains are dry evergreen forest and dry dipterocarp forest, while mixed deciduous forest may also be found. Across the lower section of the river, at least 232 species of plants can be found, including 55 species of trees, 73 species of shrubs, 26 species of vines and 38 species of water plants.

These diverse habitat characteristics and sub-ecosystems in turn nurture freshwater animals and wildlife in the area, especially the Bung-Tham forests that are predominantly swamp and forest shrubs where they can find particular or micro-niches of the ecosystems for their species.

According to the Thai Ban research, at least 28 different sub-ecosystems have been recorded in the Bung-Tham forests downstream. Taking into account the rich biodiversity, the villagers along with WWF Thailand last year managed to push for designation of a 34,400-rai area of forests and wetlands to be designated as the country’s 15th Ramsar Site, the world’s 2,420th. 

Among the great biodiversity found in the designated area are 192 varieties of fish, which are both residents of the Songkhram River itself, and migratory ones from the Mekong River.

As noted by Ramsar, many of the fish species are found exhibiting special feeding habits to particular niches in the ecosystem, such as an archerfish which ejects water from its mouth to bring down insects from overhanging vegetation (Toxotes charaneus), and a cyprinid trout-like fish, which catches small fish and insects from the surface of clearwater streams and rivers (Raiamus guttatus).

The lower basin, however, has been under threat like other basins elsewhere. Ramsar notes the factors influencing the ecosystems at the site include habitat destruction, overexploitation, alien species, chemical pollution, infectious diseases, habitat change and others such as global warming. Among these threats, it said, those causing the greatest impact are habitat destruction, overexploitation and habitat change. Other threats have the potential to cause minor or unknown impacts.

Among the species under threat are the critically endangered Baer’s pochard (Aythya baeri), the endangered sutchi catfish (Pangasianodon hypophthalmus) and the vulnerable king cobra (Ophiophagus hannah).

Mr. Suriya Kotramee from the WWF working group, which pushed for the Ramsar site listing, says that the Lower Songkhram River has been increasingly facing various threats in recent years. These include large-scale water resources development projects on the river itself, which have added further complications to the flow regime of the river.

Mr. Suriya says the villagers have felt the changes in the river section and are raising questions about the dams on the Mekong, both in Laos and in China. They suspect that these dams are the main reason for the unusual absence of Mekong’s backflow and flood pulses this year.

At present, they are also concerned about new development projects which are being additionally pushed in the area, including the construction of sluice gates at the river’s mouth and in the middle part of the river.

The National Water Resources Office says it has come up with an integrated water development plan to address what it claims are chronic issues in the basin: floods and drought. Planned projects include the construction of large sluice gates at the mouth of the Songkhram River, the middle of the river, and upstream to help regulate the flows of the Songkhram River itself and the Mekong River. In total, up to 1,644 structural and non-structural water management projects have been planned for both short-term and long-term periods (20 years) for the Songkhram River Basin. Among the top priorities are the two sluice gates on the Lower Songkhram River.

On the mainstream Mekong, meanwhile, China has constructed 11 hydropower dams in the Upper Mekong Basin, of which two are large storage dams. Another 11 dams, each with a production capacity of over 100 megawatts, are being planned or constructed, according to the Mekong River Commission (MRC).

Eleven projects have been planned for the Lower Mekong_seven in Lao PDR, two in Cambodia and two across the Lao-Thai border. Of these, two_Xayaburi and Don Sahong_have become operational, and four more have been notified to the MRC for Prior Consultation Process, according to the MRC.

Mr. Suriya says the basin has been facing increasing challenges and the impacts from the combination of various factors would become more and more complicated. Climate change, he adds, will become one of the critical factors in the near future as its impacts cannot be easily identified but will be felt strongly.

“The calls for balancing nature by the villagers will become more and more challenging as well as frustrating,” says Mr. Suriya.

Bangkok Tribune and the founder/editor of Loei Time Online, Pattravut Boonprasert, follow local backroads running deep into the Lower Songkhram River basin together and take a look at her beauty from the air.

The Songkhram River basin and lowland floodplains.
Photo: ©KAS Thailand/Pattravut Boonprasert

Bung-Tham forests (Lowland swamp and forest shurbs), Si Songkhram District, Nakhon Phanom.
Photo: ©KAS Thailand/Pattravut Boonprasert

A herd of buffaloes live freely in Chai Wan marsh.
Photo: ©KAS Thailand/Pattravut Boonprasert

The huge fish traps in Yam River, one of the Songkhram’s tributaries.
Photo: ©KAS Thailand/Pattravut Boonprasert

Fishery and aquaculture in the Songkhram River.
Photo: ©KAS Thailand/Pattravut Boonprasert

The Songkhram River and Bung-Tham forests (Lowland swamp and forest shurbs), Si Songkhram District, Nakhon Phanom.
Photo: ©KAS Thailand/Pattravut Boonprasert

The Songkhram River meets the Mekong at Ban Chai Buri, Tha Uthen District, Nakhon Phanom.
Photo: ©KAS Thailand/Pattravut Boonprasert

The Lower Songkhram River from the Air is part of Mekong’s “Wilting Womb”, the exclusive photo essay series, The Mekong’s Womb, to present to the public the values of the river basins and tributaries of the country and the Mekong region, their rich biodiversity, unique landscape and geography, livelihood and culture, which could soon vanish without a trace because of rapid development in the region.