Unraveling the Spatio-Temporal Evolution of the Ranchería Delta (Riohacha, Colombia): A Multi-Period Analysis Using GIS

The Ranchería River delta, located in Riohacha, Colombia, exemplifies the complex dynamics of coastal systems influenced by environmental and anthropogenic factors. This study analyzes the spatial and temporal evolution of the delta’s shoreline over the past two decades (2003–2023) using Google Earth imagery, the Digital Shoreline Analysis System (DSAS) within a GIS environment, and statistical methods such as ANOVA and Tukey’s test. Satellite images from 2003 to 2023 were processed to evaluate shoreline evolution through metrics like the Net Shoreline Movement (NSM) and Linear Regression Rate (LRR). The results reveal a predominant trend of accretion, with values reaching up to 260 m of NSM, particularly between 2003 and 2018. However, the 2018–2023 period shows a shift toward stabilization and localized erosion (e.g., the NSM ranges from 96 m of erosion to 32 m of accretion), with significant changes in the northeastern area (the delta’s Santa Rita arm) attributed to anthropic and natural factors (e.g., absence of mangroves or ongoing human activities). The comparison of LRR and NSM values reveals consistent linearity in shoreline behavior across the study period, suggesting stable coastal processes during accretion-dominated phases and increased variability during recent erosion. Variability across zones highlights the role of natural barriers like mangroves in mitigating erosion. The findings underscore the importance of integrating long-term data with recent trends for shoreline management and emphasize adaptive strategies to conserve critical ecosystems while addressing the socio-economic needs of local communities.