Rainfall Regime Shifts as a Proxy for Hydrological Climate Change Vulnerability

Abstract

In the context of intensifying global climate change, the hydrological system of moderately continental and arid regions exhibits extreme sensitivity. The atmospheric rainfall regime is used as a key proxy indicator to assess this vulnerability, as the deficit of atmospheric moisture and shifts in precipitation patterns directly threaten regional water resources security. This study aims to quantitatively analyze the long-term shifts in the rainfall regime within Mykolaiv region and determine their direct contribution to escalating hydrological vulnerability. To achieve this goal, a comprehensive environmental monitoring approach was employed, involving the analysis of multi-year meteorological data from 1980 to 2024, supplemented by information from geographical databases (e.g., Google Earth Engine) and official regional environmental reports. Statistical analysis methods were utilized. A detailed analysis was performed on the seasonal redistribution, frequency, and intensity of precipitation. The analysis established that the Mykolaiv region, Ukraine, is characterized by a persistent atmospheric precipitation deficit, with average annual figures critically ranging between 409 and 469 mm. The main climate factors driving hydrological vulnerability are not merely the total quantity, but the significant shifts in the pattern of fallout. Firstly, there is a clear seasonal imbalance, disrupting the region's natural hydrological cycle. Secondly, an increase in intense, short-duration storm events has been recorded. This diminishes the effectiveness of soil moisture penetration and generates rapid surface runoff, paradoxically increasing the risks of both soil drought and flash flooding. Finally, the calculation of the GTC consistently demonstrates the predominance of very dry and moderately dry conditions over many years, unequivocally confirming a clear tendency towards aridification (desertification) in the southern districts. Thus, these quantitative and qualitative changes in the rainfall regime serve as a direct and reliable indicator of the region's increasing hydrological vulnerability. These shifts negatively impact the stability of aquatic ecosystems, notably leading to the shallowness of the Southern Buh River, and necessitate the urgent development of integrated adaptation strategies to enhance water resilience.