Written by Dr. Xuezhong Yu, project leader of the MK22 project
In March 2016, Vietnam proposed for China to increase its outflow from the Jinghong Hydropower Station to the Mekong River to cope with drought and salt intrusion in a number of Vietnam’s Mekong Delta provinces. In response to Vietnam’s request, China agreed to release more water from its Jinghong Hydropower Station reservoir into the lower Mekong River in order to deal with drought in Vietnam. The water release at the Jinghong Hydropower Station was increased to 2190 m3/s on March 15 and was maintained around 2000m3/s from March 15 to April 10.
As many as 140,000ha of rice have been damaged so far, nearly 90,000 ha of which resulted in a 70 percent loss of crop across the Mekong Delta region – Vietnam’s largest rice producer. The salt invasion appeared two months earlier than before in the delta region, and the invasion length of mainstream reach was 40-93km. In addition to Vietnam, other countries in the Mekong river basin are also suffering the worst drought in recent decades.
According to the information released by the State Flood Control and Drought Relief Headquarters of China, the watershed runoff yield in the Lancang River Basin decreased by 20% since this year. The inflow to the cascade hydropower stations is only 500m3/s. The operation of the cascade hydropower project reservoirs was optimized so that Jinghong released discharge at 1000m3/s. The increased water volume released at Jinghong is 2.7 billion cubic meters so far and is 94% more than inflow. In order to alleviate the drought situation in the Mekong delta region, the Chinese government decided to further increase the release discharge to 2000 m3/s within 27 days. In Chiang Saen, the water level in the Mekong began rising rapidly from 2.3-2.5m on March 15 to 3.29m on March 18 evening.
Hydropower stations are playing important role in the Lancang-Mekong Cooperation Mechanism
This initiative is a specific action of the newly established Lancang-Mekong Cooperation Mechanism (LMCM) which was announced in the end of 2015 in Jinghong City, Yunnan Province of China. It is the first sub-regional cooperation mechanism initiated by the six countries located along the Lancang-Mekong River. Among the five directions of the LMCM, water resources collaboration is expected to be developed as a flagship filed in the LMCM.
“The discharge of water into Mekong River proves again the good cooperation on water resource management between the Mekong countries and China, which is an important part of the Mekong-Lancang River cooperation mechanism,” the Ministry of Foreign Affairs and International Cooperation said in a statement. Government officials of Cambodia, Thailand, and Vietnam also welcomed China to discharge water into the Mekong River.
Actually, this is not the first practice in which China’s hydropower projects alleviated drought in the Mekong region. Large cargo ships couldn’t pass through Chiang Sean port in Chiang Rai province, Thailand due to low water level during drought season. Recently, the situation was ameliorated when more water was released from China’s dams to increase the water level in the Mekong River, so that the large cargo ships could navigate normally. As early as 2010, hydropower projects on the Lancang River released more water to alleviate the drought in the Mekong region. Compared with these past operations, the initiative in 2016 is more targeted and the scale is larger because two huge reservoirs of Xiaowan and Nuozhadu are in commission now and the water regulation capability is much better than before. Moreover, as an operation principle, the oscillation of release flow at Jinghong was controlled below 300m3/hour so that the water level fluctuation at the outlet does not exceed 1.0 m/hour.
Transboundary Hydropower Operation Calls for Long-term Mechanism
In the future, the cascade hydropower project reservoirs on the Lancang River are anticipated to play a more important role in alleviating the impacts of extreme hydrological events. And the mitigation of adverse environmental effects also requires the operational improvement of the cascade dams. Specialists have indicated that hydropower development and operation will be the core of water resources collaboration in the Lancang-Mekong river basin as these can contribute significantly to the sustainable water use in this transboundary region. The effective operation of cascade hydropower projects in the Lancang-Mekong River Basin will advance the equitable and sustainable use of water to harmonise the interests of relevant nations and regional people’s lives. We can expect that the operation of the cascade hydroelectric projects on the Lancang River will be improved with more consideration of the economic and environmental requirements of downstream countries.
But we should be aware that the annual runoff of Lancang River is approximately 13.5% of the total runoff of the Mekong River. This means we are not able to be completely dependent on the hydropower stations on the Lancang River to help alleviate drought and flood in the Mekong countries. In the long run, we can even expect an integrated river basin operation and management scenario for key hydropower projects on mainstream and tributaries of the Lancang-Mekong River.
Long-term mechanisms of technical cooperation, communication and management are critical for the transboundary hydropower operation. The technical cooperation between Lancang-Mekong countries should be improved to study the direction and magnitude of climate change and water resources response in this region. The conditions for the hydropower operation adjustment should be determined. The academics and practitioners should also monitor the effects of hydropower adjustment and study the approaches for better results. The Lancang-Mekong countries should communicate more closely for information sharing and requirements exchange to meet the pressing needs. The Mekong countries should also understand that China overcomes practical difficulties and suffers economic loss as a result of hydropower operation adjustment. Benefit sharing and loss compensation mechanism may be considered to be established for the long-term effective operation of this initiative.
Dr. Xuezhong Yu is a senior hydro-environmental scientist at Ecofish Research Ltd. He is a water resources and environmental specialist with over 20 years of experience as researcher and consultant. In 2008-2010 he participated in the development of Hydropower Sustainability Assessment Protocol which is widely accepted and recognized globally as an enhanced sustainability assessment tool used to measure and guide performance in the hydropower sector.