Key points: Thailand and other countries in the Mekong Region have been suffering more and more severe droughts for the past five decades. Not only do they need a long-term plan to cope with the ongoing crisis, but also require regional cooperation as well. 

By Dr. Liu Hui, China Institute of Water Resources and Hydropower Research

Drought, follows flood and storm, is among the most influential natural disasters in the world. According to 2018 publication on the International Disaster Database website, 16% of people affected by disasters in 2018 were affected by droughts.

Over the past few decades, countries along the Lancang-Mekong River have experienced different degrees of drought events, causing tremendous impacts on agriculture, fisheries, production and life.

The Lancang-Mekong region is facing raising temperature like the other places in the world. According to surface temperature of January to March, 2019 is the 3rd warmest of 170 years. As news released by WMO, the Earth just had the warmest June on record.

The temperature departure from historical average is around 1 Degree Celsius in the Lancang-Mekong region in 2019.

When high temperature is accompanied with strong El Niño or weakened Southwest monsoon, long-lasting severe drought will take place in this region, like the whole-basin exceptional drought in 2016 and the long-lasting extensively affected drought this year.

A Warmer Era

According to meteorological data, the rainfall in Lancang River basin was 42 percent less than average during January to mid July 2019.

Low rainfall in early Wet Season this year was also reported by Mekong River Commission Secretariat (MRCS) in its weekly flood situation reports since June.

According to the drought index (SPEI) of January to June 2019, drought occurred in the whole Lancang-Mekong region.

For the Lancang basin, the drought severity got heavier since March, and reached severe level in May; For the middle Mekong basin (Thailand, part of Lao PDR and Cambodia), the severity of drought stayed moderate to severe level since the beginning of the year; For the Mekong delta region, the drought happened in February and April, and ended in May.

The reservoirs on Lancang mainstream stored part of the water during the wet season of 2018, and released supplementary water to the Mekong River during January to June 2019, and the water level of reservoirs gradually dropped to the dead storage level in early July.

Considering running out of the “supplementary” capacity, the Jinghong reservoir decided to implement the routine overhaul from 5th to 19th July, during which reasonable outflow was maintained.

A notification of the operation information during the overhaul was sent from the Ministry of Water Resources, China to mekong countries and MRCS in advance on 3rd July. And MRCS timely published the information on its website on 3rd July, titled Water flow from China’s Jinghong station to fluctuate, but no major impact is expected.

Recently, news coverage about drought this year has been increasing and drawn more and more attentions from farmers to senior administration officials.

According to the Cambodia Daily on July 20, 2019, an extended drought in Cambodia has caused the tributaries of Tonle Sap lake to dry up, spelling ruin for farmers and fishermen in Battambang province. Villagers in this district have been unable to fish since April because of the drought. They are now running out of food and have pleaded with the government to give them emergency relief.

The drought situation in Thailand is so severe that the government has asked China, Laos and Myanmar to release more water into rivers to help relieve the drought conditions in Thailand said Prime Minister Prayut Chan-o-cha on 24 July 2019.

Based on long time observation and research on the drought study in the Lancang-Mekong region, I would like to take this opportunity to share my findings and suggestions with riparian stakeholders and decision makers, with the aim to improve our drought relief ability jointly to make a more secure Lancang-Mekong region.

Findings

(1) The results of meteorological drought analysis show that the drought severity in northeastern Thailand, most of Cambodia and Myanmar has increased over the past half century, especially in some parts of northeastern Thailand.

In most parts of the basin, the frequency of meteorological drought is close to 25% due to low rainfall, especially in northeastern Thailand and Cambodia; and Cambodia and Vietnam Delta in the lower reaches are more liable to severe and exceptional droughts.

By analyzing the causes of typical drought events, it is found that the main reason for the drought in the Mekong River Basin is the extraordinary less rainfall (compared with that in the same period in history) caused by El Nino and anomalies of atmosphere-ocean circulation system.

(2) Because of the differences between the national economic supporting capacity and development of water conservancy projects, the drought resistance ability of different countries is different.

Among them, the distribution of irrigated areas is uneven in Cambodia and the ability of drought resistance in different regions is different. The number of irrigation projects and irrigation area in Lao PDR is relatively small and drought resistance ability is slightly inadequate.

Vietnam and Thailand have built relatively high-density, large-scale irrigation projects and irrigation network, which is expected to provide a better engineering guarantee for the development of drought resistance.

Suggestions

(1) Exploit potentialities and enhance the ability of countries to cope with natural disasters.

The Mekong River Basin countries have established organization system for disaster prevention and reduction to deal with drought disasters.

Although there is a significant correlation between the national drought relief capacity and economic and social development level, the consensus of the whole basin on improving the drought relief structural measures is also very important.

Based on the viewpoint of engineering, though countries like Thailand and Vietnam have taken adequate measures to combat drought, it seems still necessary to enhance the drought relief engineering construction to cope with severe drought.

(2) Make overall plans and coordinate to enhance the disaster mitigation ability from the whole-basin perspective.

Though the reservoirs on Lancang mainstream have played a “supplementary” role by using the storage and regulation capacity and released about 140 percent more water than that of natural flow this year to the Mekong River during January to June 2019, the low water level status of hydrological stations on lower reaches of the Mekong mainstream still occurred.

It is due to the fact that the flow contribution of Lancang River to the whole Lancang-Mekong basin is only around 20% and 11% in dry season and wet season respectively. When whole-basin drought happens, more measures should be considered from the whole-basin perspective.

It is suggested that the tributaries along the mekong river should play more important role in regulating and storing water. Besides, The reservoirs built in the Mekong River Basin have a capacity of more than 20 billion m3.

It is suggested that the possible positive role of these reservoirs in drought relief in all countries and the whole basin should be studied in depth, and the impacts of drought relief projects on the water disasters in the downstream regions or countries should be deeply analyzed while they alleviate the local disasters to lay a foundation for the overall coordination of the basin.

(3) Make full use of the regional cooperation mechanisms to promote the whole-basin cooperation level.

Among the several cooperation mechanisms in the Lancang-Mekong region (MRC, GMS, Golden Quadrangle Program etc.), the Lancang-Mekong Cooperation (LMC) mechanism was established by all six riparian countries of Lancang-Mekong River in 2016, which provides a new platform for dialogue and cooperation from the whole basin perspective.

Water resources is one of the five priority areas under the LMC mechanism. Joint Working Groups on water resources under the LMC mechanism consisting of line agencies of the six LMC countries and the Lancang-Mekong Water Resources Cooperation Center established in Beijing, which mark the establishment of Lancang-Mekong Water Resources mechanism in 2017.

The following cooperation topics are recommended to be carried out under the Lancang-Mekong Water Resources mechanism.

They include enhancing information sharing and countermeasure consultation through Joint Working Groups on water resources of LMC, research on climate change impacts and adaptation measures in the Lancang-Mekong basin and research on joint operation of the reservoirs in the whole basin, so as to make full use of the regulation capacity to cope with natural disasters.

Note: Dr. Liu Hui was the project leader of “Joint Assessment on Flood Prevention and Drought Relief in Mekong River Basin (Phase I)”, which was carried out by experts from six member countries under the Lancang-Mekong Cooperation mechanism in 2018.

She is also among the core experts of the joint research “Hydrological Impacts of the Lancang Hydropower Cascade on Downstream Extreme Events” in cooperation with MRC and IWMI.

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