Floods and related problems after the 1980s in Khovd, Western Mongolia

Abstract Global warming has increased flood hazards, even in semi-arid regions. The extremely low normal surface water flow in these regions complicates hazard assessment and flood risk awareness. In this study, we first investigated recent flood trends since the 1980s in the major city of Khovd using meteorological data and satellite images to clarify climate change and its impacts in western Mongolia, which have not been reported before. The results showed that the frequency of heavy rain has increased gradually, despite a significant decrease in total annual precipitation. 75% of the total precipitation in the city of Khovd occurs in summer. Moreover, the frequency of daily precipitation exceeding 10 mm and the maximum daily precipitation have increased, and the frequency of flooding has increased since 1987. We also found that traces of floods were clearly recorded in Landsat images nine times since 1992 to 2022. The Buyant River, which flows northward along the western edge of Khovd, has not flooded in the past few decades, but flash floods flowing directly down from the southern mountains have struck Khovd. The study also revealed poor flood control structures and a lack of knowledge among residents. As a Mongolian custom, many residents spend the summer in ger s (mobile living tent) along the Buyant River, and the increase in the flow rate of the Buyant River over the past few decades further increases the risk of disaster. To reduce the increasing risk, it is necessary to strengthen flood control facilities and raise awareness pertaining to the lifestyles of local residents. This example is likely to be universal for reducing flood risk in semi-arid Asia.