UPSTREAM DROUGHT AND DOWNSTREAM FLOODING

By Rim Sokvy, The Mekong Research Project

The Mekong River, which stretches from China (Lancang River) through Myanmar, Thailand, Laos, Cambodia and Vietnam, is crucially important for the livelihoods of hundreds of millions of people. The river is the primary source of freshwater, fish protein, irrigation and energy. As hydropower dam construction continues, there is much debate about the rise and fall of water levels, particularly in the lower Mekong River. Of all the world’s major rivers, the Mekong has the greatest seasonal variation of water levels. China is often criticized by non-regional powers as the chief contributor to both drought and flooding in the lower Mekong. However, the recent heatwave and drought in China along the Lancang and Yangtze rivers is not the cause of the significant flooding occurring in Thailand, Cambodia and Laos.

Photo source: The Star

On August 18, the Lao Government warned citizens living along the Mekong and its tributaries about rapidly rising water levels. Five Lao hydroelectric plants; Nam Khan 2 and 3, Man Lik 1-2, Nam Kong 1, Nam Ou and Xayaburi Dam, needed to release water. Flooding occurred in many areas in the country including Hauphanh, Luang Prabang, Xayaboury and the Lao capital Vientiane after torrential rain from tropical storm Mulan. The Lao government deployed 600 military personnel to evacuate citizens from the area after flooding interrupted the water and energy supply and destroyed roads, bridges and other infrastructure. The Lao Department of Public Works and Transport has allocated an emergency budget of LAK 20 billion (US$1.3 million) to tackle the flooding, repair infrastructure and enlarge and clear run-off channels. 

In Cambodia, the Ministry of Water Resources and Meteorology released a rain forecast on August 14, that Cambodia would experience heavy rain within the next seven days. On August 15, The Khmer Times reported that 16 of Cambodia’s 25 provinces were experiencing flooding due to heavy rain falls. On August 24, the acting governor of Kampong Leng district, Cheng Chanbona, told The Phnom Penh Post that rising water levels in Tonle Sap Lake posed serious danger of flooding. In the central province of Kampong Chhnang, authorities closed Highway 50C, which connects to Kampong Thom province, due to flooding resulting from heavy rains, fast flowing water in the Mekong and resultant fluctuation of Tonle Sap Lake water levels. As of 28 August, authorities in the northern Preah Vihear province warned citizens living along the Mekong River and its tributary, the Stung Sen, to evacuate as water levels approached 12m, 0,5m over the alert level. By August 30, the water level had risen to 12.72m. Over 5345 hectares of rice and other plantation fields in Preah Vihear were damaged by flooding, along with roads and other infrastructure roads and 74 families were evacuated from inundated areas.

Thailand’s National water Command Centre also issued flood warnings noting that heavy rainfall in Laos would cause rising water levels along the Mekong and potential flooding. Since 14 August, 11 of Thailand's 77 provinces have experienced flooding and the Meteorological Department of Thailand warned that heavy rainfalls around Bangkok may cause flooding in the capital. In the Northeast of Thailand, and particularly in Nakhon Phanom, Udon Thani, and Sakon Nakhon provinces, heavy flooding caused significant damage to agricultural land and production. The area along the Mekong was undergoing severe flooding. Around 84,737 rai (1 rai = 1,600 square metres) of rice fields and plantation were inundated. The serious flooding in Thailand, Laos and Cambodia are a result of the torrential rainfalls generated by tropical storm Mulan and seasonal monsoon rains.

Photo source: The Guardian

In China, however, the upper reaches of the Mekong, known as the Lancang, and the Yangtze have experienced severe drought since 2021. A severe shortage of water has disrupted both energy supplies and riverine transportation, which has negatively affected production supply chains. Important manufacturers including Foxconn, Tesla and Toyota have suspended some operations due to an 80% reduction of hydropower across the region. Moreover, the spillover effects of China’s water shortage was of serious concern to other countries in the region due to decreased Chinese exports of foodstuffs such as rice. Despite recent rainfalls and reports of flooding in some parts of Sichuan, China’s meteorological agency is still concerned with drought conditions warning that the government will need to reserve water supply in case of a second, more severe, wave of drought. The difficulties faced by the six Mekong countries due to the disparities of upstream and downstream conditions points to the necessity of increased engagement with China and a more holistic approach to the overall management of the Mekong from its source on the Tibet/Qinghai plateau all the way to its vast estuary in Vietnam.