Dam Projects Likely to Negatively Impact Longer-Term Security Environment in South and Southeast Asia

China has approved plans to construct the world's largest dam on the Yarlung Zangbo River, which flows into the Brahmaputra near the Indian border. While China claims the project will not harm downstream countries, several concerns persist. These include the risk of community displacement, ecological degradation, and China's strategic use of such projects to increase influence along the border region. Due to the remote locations of China's Brahmaputra dams within Tibet, the construction of the dam requires significant infrastructure development, including road, rail links, and housing for the workers and their families. Beijing can use the creation of such dams to exert greater influence over its peripheral and disputed areas, particularly near the contested Arunachal Pradesh State, which China claims as part of “Southern Tibet.”

Although Sino-Indian border tensions have reduced since both states agreed to greater dialogue and cooperation in October 2024, China's influence over the flow of the Brahmaputra River continues to create anxiety in New Delhi over border disputes. China has deliberately ceased sharing data on water figures with India since their 2017 border stand-offs, making it harder for India to predict water flows during monsoon seasons.

The proposed dam location also lies in a seismically active region. It could pose a significant risk to downstream areas in India and Bangladesh should an earthquake severely damage the dam. Besides the risk of earthquakes, the Brahmaputra is prone to severe flooding and erosion in the spring, when the Himalayan snow melts, and in summer, due to monsoonal rains.

Recurrent flooding along the Brahmaputra River has prevented India from accessing critical border areas in Arunachal Pradesh, severely damaging roads, bridges, and communication lines. This has increased concern in New Delhi that in a future conflict, China could exploit dam control and deliberately flood the region to disrupt Indian military movement or delay a counteroffensive to an invasion. In a likely response to these concerns, India has consequently began building three dams along the Brahmaputra River and its tributaries to ensure they maintain greater control over water flow and mitigate large-scale flooding in the future.

Studies show that dry season flows on the Mekong River can be unstable or severe, in some areas for extended periods, with droughts becoming more intense and frequent in the early dry season November-January. Climate change, with continued warming and increased climate variability, will likely exacerbate water shortages.

The Mekong is also an important inland waterway for traditional cargo, passenger transport, and international trade route between numerous riverine communities along the river and wider international markets. Further reductions in the water levels in the river are likely to extensively impact international and domestic trade.

A 2022 agreement between Cambodia, China, Laos, Myanmar, Thailand, and Vietnam to conduct a joint study on the Mekong River's changing hydrology marked a notable step forward in regional water diplomacy. For nearly two decades, China had only shared wet-season data with downstream countries. Under the new agreement, it committed to sharing dry-season flow data as well—an important development given that water levels are most sensitive to dam operations during this period. 

A decrease in sediment concentrations due to dams upstream will substantially change the rivers' morphology. The Ganges-Brahmaputra Delta is particularly vulnerable as the Brahmaputra River is a relatively young river and highly susceptible to channel migration. Irrigation is the main water user in the Brahmaputra and Mekong basins at 80 and 70 percent, respectively. Water scarcity and a reduction in arable land are likely to result in reduced agricultural yields and food insecurity.

Recent droughts close to the coastal areas of the Mekong River Delta have left more than one million Vietnamese without freshwater to use for agriculture. They have also led to salinity intrusion, making the land unusable. As a result, Vietnam views the Delta as a food and economic security risk due to its reliance on goodwill from countries that have greater power over the flow of water.

Hanoi has therefore become hostile towards infrastructural projects that could affect the flow of the Mekong, including Cambodia's proposed Funan-Techo canal project. This project would see Cambodia create a direct 180-kilometer (112-mile) link between the port town of Kep upstream to the Phnom Penh Autonomous Port along the Mekong River. This would allow Cambodia to ensure a direct shipping link from the Gulf of Thailand to the Mekong, bypassing parts of the Mekong owned by Vietnam. Hanoi has expressed concerns over this project due to the minimal environmental impact studies, with its main problem being that the canal could divert water from the Mekong Delta and exacerbate future droughts. 

Downstream countries in South and Southeast Asia increasingly regard water insecurity—driven by the dual threats of flooding and scarcity—as a critical national security concern. Climate change, environmental degradation, and population growth will intensify the situation. However, the ability of downstream countries to respond remains limited to frameworks like the "No Harm Principle,” water sharing agreements, diplomatic dialogues, and international legal systems. Thus, these transboundary rivers could drive regional tensions and act as a flashpoint among affected local populations along the border regions.

Learn more about leveraging our industry-leading regional and subject matter experts for intelligence that helps your organization stay ahead of risks to your people and operations.