ABSTRACT The combined effects of climate change and anthropogenic activities induce significant sea-level alterations, changing beach morphologies. While the effects of water level rise on coastal regions have been extensively studied, the consequences caused by water level fall, particularly in enclosed water basins, have received limited attention. The Bruun rule is an empirical approach for estimating the erosion of sandy beaches in response to sea level rise. This study evaluates the efficacy of the Bruun rule and associated methods under water-level fall conditions. An extensive investigation was followed to understand Bruun’s rule application and its hypotheses in this context. Cross-shore profiles were collected from three stations: Larim, Farahabad, and Miankaleh, located along the southeastern coast of the Caspian Sea between 2013 and 2021. Results indicate that Bruun’s predictions are more reliable, considering their accuracy and applicability. Additionally, active zone bed slope emerges as the most significant factor influencing Bruun prediction, performing well with slopes between 0.013 and 0.016. Moreover, Bruun’s hypotheses were assessed by comparing the observed profiles and water levels over 7 months, 2 years, and 3 years, revealing a lag time contradicting Bruun’s hypothesis. Results further indicate that the Bruun rule overlooks the impacts of water level fluctuations.
Read full abstract