This study investigates the evolution of the Rakaia River mouth barrier, the processes influencing its morphology and position, and its impact on the local Rakaia Huts community. This is done by analyzing 30 years of beach profile, river cross-section, and marine/fluvial data. Analysis of LiDAR using Arc GIS Pro along with data manipulation and presentation in Excel was used to enhance our understanding of barrier dynamics. Additionally, statistical analysis of time series data using R Studio and Excel allowed us to examine the influence of various factors such as river flow, wave action, sedimentation, and storm events, on the barrier's erosion and sediment transport patterns.

Our findings revealed a significant shift in the barrier's positioning over time. Between 1991 and 2008, the barrier exhibited progradation of 134 m, advancing towards the sea. However, since 2008, it has undergone a notable retreat of 60 m. Meanwhile, the beaches on either side of the barrier have continued to prograde, highlighting the complexity of coastal processes and likely interplay of sediment transport from the river to the coast. These findings have significant implications for flood management practices and community planning in the Rakaia Huts region. By understanding the historical and ongoing changes in the barrier, local authorities can make informed decisions to mitigate potential risks and safeguard the community. This research contributes to our broader knowledge of coastal barrier systems, particularly the complex interaction of hydrological and coastal processes under both natural and human-induced influences.

While this study does provide valuable insight, it is essential to acknowledge limitations. The reliance of the study on pre-collected data may have restricted the accuracy of the analysis. Future research could benefit from real-time data collection, or at a more sub-annual temporal scale, and the use of advanced techniques like drone-based aerial imaging and repeat LiDAR to ensure the data is accurate.

In conclusion, this study identifies the timing and drivers of key shifts in barrier position for the Rakaia River mouth barrier. Increased knowledge and a thorough analysis of its evolution contributes to the current understanding of the hydrological and coastal processes shaping the barrier, and implications for the local community.