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Multitemporal assessment of changes in land cover associated with water transfers in dry forests: case study of the Chongón–El Azúcar system (Ecuador)

Abstract:

Tropical dry forests (TDFs) support biodiversity and ecosystem services but are increasingly exposed to anthropogenic and climatic pressures. Interbasin water transfers (IBWTs) reconfigure hydrology and can promote land-use/land-cover (LULC) change, yet their effects on Neotropical TDFs remain poorly quantified, particularly in Ecuador. This study characterizes LULC dynamics and drivers of forest loss in tropical dry forests within the area influenced by the Chongón–El Azúcar IBWT system (Ecuador) between 2019 and 2025. Cloud-free Sentinel-2 Level-2A mosaics were compiled for both years, and five LULC classes were mapped using seven optical bands and five spectral indices (NDVI, SAVI, MNDWI, NDCI, and NDBI) as predictors in a Random Forest (RF) classifier. The classifications showed very high performance (overall accuracy 97.89–100%; κ = 0.94–0.99). A transition matrix quantified gross and net LULC changes, and a pixel-based LASSO-penalized logistic regression related TDF loss to distance from the IBWT canal and spectral predictors (AUC = 0.9599). Between 2019 and 2025, TDF experienced a net loss of 1,223.77 ha, while agricultural land expanded by 756.21 ha, largely at the expense of forest, with most conversions concentrated within 0.15–0.30 km of the Chongón–Sube y Baja canal and around the El Azúcar reservoir. The turbid-water class in the reservoir increased by 145%, consistent with higher aquatic biomass and eutrophic conditions. Distance to the canal, low vegetation indices (NDVI and SAVI), and high water- and built-up–related indices (MNDWI, NDBI) significantly increased the probability of TDF loss, providing empirical support for 0.15–0.30 km ecological buffers and operational spectral thresholds to flag high-risk areas. We recommend redirecting agricultural expansion to already transformed soils, establishing riparian buffer strips along canals and reservoirs, strengthening nutrient management and aquatic macrophyte control, and implementing an operational satellite-based monitoring programme to inform land-use planning and the conservation of Neotropical TDFs affected by IBWT projects.