# The Influence of Hard Protection Structures on Shoreline Evolution in Riohacha, Colombia
## 1 Introduction
[21] examined the evolution of 12 shore platform beaches along the Cascais coast, Portugal, using Digital RGB orthophoto maps. [PERSON] et al. [22] integrated satellite imagery with UAV-based photogrammetry to assess beach-cliff erosion at Pacheco Beach, Brazil. [PERSON] et al. [23] used Landsat-8 imagery and automatic shoreline extraction to analyze anthropogenic impacts on the Maravanthe Coast, India, revealing an 8% decrease in erosion zones and a 7% increase in accretion zones. Beyond natural processes, human interventions--such as coastal protection structures--play a key role in shoreline evolution. Hard engineering solutions like seawalls, groins, and breakwaters are often implemented to mitigate erosion, but they can significantly alter sediment dynamics. While these structures may stabilize targeted areas, they often induce downdrift erosion, disrupt natural sediment transport, and modify deposition patterns, leading to unintended consequences for adjacent coastal systems [24]. As a result, historical data and predictive modeling are essential for forecasting future shoreline changes and adapting coastal management strategies accordingly [25]. Numerous models of varying complexity have been developed to estimate and predict coastal erosion, helping to project shoreline positions and assess risks. Among these, key approaches include the Bruun rule [26], the Kalman filter method [27; 28], historical data extrapolation [20], the Coastal Evolution Model (CEM) [29], XBeach [30], and the Generalized Model for Simulating Shoreline Change (GENESIS) [31]. These models can be applied individually or in combination, depending on the specific coastal environment, data availability, and study scale. Integrating multiple models and validating them with field data enhances the accuracy and reliability of coastal change predictions. This study investigates coastal development in the urban area of Riohacha, the capital of La Guajira Department on the Colombian Caribbean coast. Although research on shoreline dynamics and erosion modeling has advanced considerably in recent years, few studies have applied a combination of predictive modeling approaches in the Caribbean context, particularly in medium-sized urban areas with significant geomorphological heterogeneity and infrastructure pressures. This lack of integrated modeling applications limits the ability to assess future coastal risks with higher confidence. The present study addresses this gap by applying and comparing three modeling techniques--HTA, EHD, and KFB--along a representative coastal segment of the Colombian Caribbean. It aims to analyze the potential correlation between the construction of seven groins and the resulting coastal changes, specifically the growth of the coastline where the structures are located and the erosion observed in the southern cliff zone. The primary hypothesis is that the groins have contributed to the stabilization and accretion of the coastline near the structures, while inducing erosion further south, leading to a cause-and-effect relationship between human intervention and coastal response. For this purpose, the images available before (1987-2006) and after (2009-2022) the anthropic interventions have been rectified, profiled, and analyzed. The work includes the statistical analysis of the evolution of coastlines; the calculation of modified surfaces; and the application of predictive models (up to 2045) that should serve as a basis for future land management, providing a point of support for decision making in any coastal region.