In-depth exploration of precipitation dynamics in the Wadi El Bey watershed (North-eastern Tunisia): comprehensive study of rainfall variability and its relationship with teleconnection patterns

This study is interested in examining monthly precipitation data, registered over the period (1980–2019) in eight rainfall stations in the Wadi El Bey Basin (North-eastern Tunisia). First, inter-annual rainfall variability is examined using statistical elementary analysis, Bertin matrix and the Continuous Wavelet Transform (CWT) method. Next, the relationships between monthly rainfall and climatic signals are established based on the Wavelet Coherence (WC) method. Elementary statistical analysis, the Bertin matrix, and CWT highlighted both temporal and spatial variability of precipitation in the study area. Temporal variability manifests itself both in the short term, characterized by seasonal effects, and in the medium and long terms, revealing an alternation between wet and dry years. Spatially, the results indicate that the watershed can be divided into three distinct zones, with the most significant precipitation occurrences located in the north and the northwest. WC analysis showed a significant correlation between monthly precipitation data and different climatic indices. The Mediterranean Oscillation (MO) and the Atlantic Multidecadal Oscillation (AMO) indices were found to be highly correlated with precipitation at the annual scale. At the interannual scale, rainfall variability was shown to be mainly related to the South Oscillation Index (SOI) and to Antarctic Oscillation (AAO) at the 8–12-year mode, introducing a novel perspective and shedding light on a previously unexplored climatic factor affecting regional precipitation patterns. The insights gained from this study may be useful in the development of decision-aid tools, resulting in more effective disaster risk mitigation strategies and enhancing water management practices in the region.