Climate change has exerted a significant impact on the hydrological conditions of the Lancang-Mekong River Basin (LMRB), according to Tian Fuqiang, a professor of hydraulic engineering at Tsinghua University. He said that data substantiates the notion that, over the past 120 years, climate change, especially extreme weather occurrences, has escalated the frequency of droughts.

"The decade from 2010 to 2020 saw notable drought incidents, such as the severe droughts in 2016 and 2019-2020, primarily caused by El Niño phenomena rather than factors like reservoir construction," Tian said.

Tian referred to the research findings of "Phase 1 of the Joint Study on the Changing Patterns of Hydrological Conditions of the Lancang-Mekong River Basin and Adaptation Strategies," conducted by the Lancang-Mekong Water Resources Cooperation Center and the Mekong River Commission Secretariat. 

Researchers used the Standardized Precipitation Index (SPI), the Standardized Precipitation Evapotranspiration Index (SPEI), and the Standardized Runoff Index (SRI) from sources of the Climate Research Unit gridded Time Series, ERA5-Land, and Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) to analyze droughts.

The technical report of the Phase 1 research, completed in August 2023, concluded that "climate change shows significant impact in the basin," based on the analysis of long-term trends, frequency, duration, intensity, and the role of El Niño. 

The report notes a remarkable similarity in drought frequency changes between 2000–2009 and 2010–2020 for meteorological droughts (SPI by CHIRPS) and areal hydrological conditions (SRI by Variable Infiltration Capability model) over the Mekong River Basin.

It says that both dry and wet seasons show trends toward more severe droughts over large areas of the LMRB, and the period of 1950–2021 shows considerable spatial changes in both these indexes when compared to 120-year data (1901–2021). This suggests that the trend towards "drier" conditions is more recent and is likely to be related to the changing climate.

The report also indicates that meteorological droughts in the LMRB are significantly influenced by El Niño events, with their intensity serving as a reliable indicator of the severity of meteorological droughts in the basin.

Tian said that global climate change and the resulting more severe droughts and floods will have an increasingly significant impact on hydrological conditions in the basin, making it crucial for countries in the area to share more meteorological and hydrological information. 

The information-sharing platform under the Lancang-Mekong Cooperation framework serves as an important mechanism to facilitate this process, he said.

The professor also stated that, in addition to natural factors like climate change, human endeavors such as infrastructure development and water management also interact with natural factors and affect the total water volume, duration, and distribution of water in the basin.

"Hydrological changes are constantly occurring, and the dominant factors vary depending on the time and location, requiring specific analysis," Tian added, noting that it is important to accurately understand these impacts and changes and actively pursue mitigation and adaptation measures.

He called on Lancang-Mekong countries to strengthen coordination and cooperation based on the principles of fair and reasonable utilization to jointly address the impacts of climate change on water resources.

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