| 08 Aug 2025
A shifting pattern of tropical cyclone induced high river discharges in the Greater Mekong Region, 1970–2019
Abstract. On average flood events impact over 100 million people globally every year, and because of demographic changes and economic development in flood-prone areas, as well as climate change, the population exposed to flood risk is expected to double by 2050. Under anthropogenic climate change it is expected that flood events previously considered extreme will be occurring with more frequency, due to changing patterns of precipitation in a warming climate. It is, therefore, critically important to better understand how extreme weather events generate high river flows in exposed regions. Here we look specifically at the influence of precipitation from tropical cyclone (TC) activity on high river flows within one such exposed region: a 1.2 million km2 area of South-east Asia encompassing the entirety of the Mekong and Red River catchments, plus 13 smaller catchments along the coastal fringe of Vietnam (collectively referred to here as the Greater Mekong region, or GMR). We use a hydrological model (GM-HYPE) with ERA5 precipitation data to simulate streamflows over the last 50 years (1970–2019) with, and without, TC-linked precipitation. Our results demonstrate that TC-linked precipitation around the GMR generate notable increases in high (95th percentile) streamflows, and this is most notable in the steep sub-catchments draining to Vietnam’s northern coastline. These locations are more exposed to TC activity, and we determine that the elevated soil moisture levels there from monsoonal precipitation, prior to the typhoon season, are an exacerbating factor. Furthermore, trend analysis also shows that shifts in the spatial locations of TC-induced high river flows have been occurring since the 1970s: while statistically significant increases in TC-induced high river discharges are evident in localised regions of the GMR including the highlands of Laos and the Mekong’s delta region, declines in TC-induced high river discharges are much more widespread, with notable declines in the headwater and middle reaches of the Red and Mekong Rivers. Our findings on the changing pattern of high river flows in recent decades, in a region highly exposed to TCs, will be of great interest to strategic planners and flood managers. We conclude with a discussion on the impact of global climate model precipitation projections for this region, contrasting past/present (1980–2014), and future (2016–2050), GM-HYPE model results.
The paper quantifies the influence of TC activity on high river flows within a 1.2 million km2 area of southeast Asia encompassing the Mekong and Red River catchments, plus 13 smaller catchments located along the coastal fringe of Vietnam. In 2020, this Greater Mekong Region (GMR) supported a population 85 of over 160 million people.
1.The use of a 500km radius to crop TC related precipitation in the article does not fully demonstrate the applicability of this radius in the GMR region.
2.Table 1 only considers three variables (precipitation, soil moisture, slope), ignoring possible important factors such as land use, reservoir regulation, and previous rainfall. Suggest explaining the possible impacts of these potential factors in the discussion.
3.The author points out that the reliability of data in the 1970s and 1980s was low, but does not evaluate the specific impact on trend analysis.
4.Figure 5 shows future changes, but does not provide confidence intervals or inter model differences (such as multi model sets).
5.The abstract should succinctly summarize the research objectives, methods, key findings, and conclusions. I suggest reducing background information in the abstract and focusing more on the study's highlights and outcomes.
6.Some newest research work related with this paper can be added in the introduction. Diffusion evolution rules of grouting slurry in mining-induced cracks in overlying strata. Water injection softening modeling of hard roof and application in Buertai coal mine.
7.The conclusion mentions “useful for planners and managers”, but does not provide specific recommendations (such as which areas should prioritize strengthening flood control facilities). The authors should provide a summary of their main findings, the limitations of the study, and recommendations for future research in the conclusion.
8. There are several grammar mistakes in the paper, please revise and double-check throughout the whole manuscript. The language could benefit from further editing and polishing.