Hydrological response to climate change: Dam inflow dynamics in the Côtier Constantinois East and Medjerda-Mellegue basins

Abstract

In a context of increasing climate change, this study evaluates the impact of climate variability on water resources. To achieve this, it analyses annual inflows were analysed at 15 stations located upstream of dams in the Côtier (Coastal) Constantinois East and Medjerda-Mellègue watersheds between 1958 and 2024. Several statistical methods were employed, including Pettitt's breakpoint test, the Mann-Kendall trend test, Sen's slope, the Standardised Runoff Index (SRI) and Innovative Trend Analysis (ITA). The results reveal a significant and persistent decrease in annual inflows, with breaks in the data identified as early as the 1970s in the south and from the 1990s onwards in the north. Reductions observed range from 38% to 47% in the north, exceeding 70% in the south. The SRI index indicates a predominance of drought periods in the south, whereas the north experiences a more balanced cycle of wet and dry periods. The Mann–Kendall test and Sen’s slope estimator consistently indicate significant decreasing trends in annual inflows at most stations. This is further supported by the Innovative Trend Analysis (ITA), which confirms a generalized decline across the study area. These results emphasise the clear impact of climate change on regional hydrological regimes and the necessity of adapting water resource management strategies.