Annual before–after–control–impact detection and mining-scenario sensitivity in a coastal sandy basin, southeastern Madagascar (1993–2022)

This version supersedes the previous version. It corrects the earlier interpretation of mining-specific soil-water storage change by replacing the previous before/after framing with an explicit mine–reference BACI interpretation. The revised analysis no longer supports a strong annual mining-specific ΔSW deficit as stated before; instead, it indicates weak annual BACI contrasts and a dominant shared regional trajectory, while retaining scenario results as mechanistic sensitivity tests. The hydrological effects of coastal mines are difficult to separate from regional basin trajectories, particularly in tropical systems with sandy soils, wetlands and strong interannual variability. This study re-evaluates mine–climate interactions in the Taolagnaro basin of southeastern Madagascar using Soil and Water Assessment Tool (SWAT+) simulations for 1993–2022 and a mining-versus-reference before–after–control–impact (BACI) design centred on a 2008 threshold. Annual hydrological response unit (HRU) water balances are aggregated by area weighting to compare the Mandena mining footprint with an internal basin reference zone. No annual hydrological variable shows a post-2008 BACI contrast that clearly exceeds interannual variability. Percolation yields the most pronounced mean negative contrast but remains too dispersed to constitute an isolated mining response. Post-2008 trajectories of the mining and reference zones evolve largely together, indicating a dominant regional dynamic. A low/mid/high scenario chain nevertheless shows that SWAT+ strongly redistributes the water balance when a disturbance is imposed on the mining HRUs. The study therefore distinguishes annual BACI detection from simulated mechanistic sensitivity, and cautions against over-attributing post-2008 hydrological change to mining at the annual scale in this coastal setting. This is an independent author version released under CC BY 4.0.