A remote sensing–based assessment of long-term vegetation dynamics following dam construction in a Mediterranean watershed (Cyprus)

This study presents a methodological framework to assess the impact of dam construction on vegetation dynamics, using the Klirou–Malounta–Akaki Dam in Cyprus as a case study. Unlike many dams that incorporate controlled flood pulses, this structure lacks a designed flood regime, raising the question of whether observed changes in riparian vegetation are primarily driven by localized microclimatic or geomorphological factors rather than direct hydrological alterations. A temporal analysis covering 20 years before and after dam construction (1984–2024) was implemented to distinguish baseline vegetation conditions from post-construction shifts. The analysis focused on a downstream area within the Serrahis River watershed. Enhanced Vegetation Index (EVI) time series, derived from Landsat 5, 7, and 8 and processed via Google Earth Engine and R, were harmonized using a Random Forest cross-sensor calibration approach. Pixel-wise trend analysis at 30 m resolution revealed cluster areas of vegetation increase, suggesting localized greening effects. However, ground-truthing surveys revealed that such increases were often associated with the spread of non-native Eucalyptus spp., a drought-tolerant species adapted to stable or intermittent surface flows. While the EVI trends may imply ecosystem recovery, they also indicate a shift in species composition, potentially favouring resilient non-native taxa at the expense of native species reliant on seasonal flooding. These findings underscore the importance of interpreting vegetation indices in post-dam riverine ecological contexts. Although stabilized hydrology may enhance water storage, it can drive biodiversity loss, highlighting the need for balanced water management strategies in water scarce Mediterranean environments.