Possible causes of abnormal spring flooding in Kazakhstan in 2024

In the spring of 2024, Kazakhstan experienced significant flooding that caused the submersion of numerous settlements and transportation infrastructure. The hydrological regime of rivers in the plains of Kazakhstan is characterized by short-lived spring floods and a summer-autumn-winter low water period. The volume of spring runoff can vary greatly from year to year, sometimes by more than 100 times. The arid and dry climate of Kazakhstan is characterized by hot summers, cold winters, and relatively low precipitation levels, ranging from 350 to 500 mm per year. The volume of spring flooding is mainly determined by the ability of the soil to facilitate the transit of meltwater to the riverbeds during the active snowmelt period. Therefore, snow deposit, winter soil freezing, and the dynamics of seasonal snow thawing play the key role in controlling the regime and scale of spring runoff. Weather factors related to the formation of large volumes of spring floods are very diverse, from autumn soil moisture before the formation of a stable snow cover to weather conditions during active snowmelt days. This study examines a number of key weather parameters related to the formation of the spring flood in 2024. On the basis of data from FEWS NET USGS (Famine Early Warning Systems Network by U. S. Geological Survey) products, 20-year time series of Soil Moisture Anomaly (December) and Snow Water Equivalent Anomaly (February 15) were considered. The ERA5-Land reanalysis data, which combines forecasts from the ECMWF ERA5 (European Centre for Medium-Range Weather Forecasts Reanalysis v5), climate models and ground-based information from the World Meteorological Organization have been used to characterize the temperature regime of the Arctic intrusion of extremely cold air in Kazakhstan in the second half of February 2024. It was concluded that the abnormally high soil moisture at the beginning of the winter and extremely cold air at the end of the winter resulted in a low soil absorption capacity in Kazakhstan during the spring snowmelt. As a result, the meltwater was effectively collected in river runoff, leading to a significant scale of spring flooding. Local weather conditions during the active snowmelt days in the 2024 season did not play a significant role. It appears that the abnormally high level of spring flooding was inevitable regardless of the spring weather conditions.