Regime shifts in the multi‐annual evolution of a sandy beach profile

Abstract

Extreme storms occasionally induce extraordinarily large morphological changes, which may have major impacts on coastal resilience, tourism and the environment. Some of the changes are persistent, and they are defined as regime shifts. During a 28‐year period from 1986 to 2014, the foreshore and the inner transition zone of the Hasaki coast of Japan underwent four morphological stages separated by regime shifts in beach profiles. From stage 2 to stages 3 and 4, over a relatively short period between 2006 and 2008, the beach profiles in the foreshore and the inner transition zone drastically changed, mainly because of large offshore waves. From stage 2 to stage 3, the foreshore and the inner transition zone were greatly eroded. Then, from stage 3 to stage 4, although the inner transition zone was further eroded, the foreshore underwent accretion. The severe erosion of the inner transition zone over the 2‐year period formed a steep slope, which was inferred to have led to accretion in the foreshore in stage 4. Stage 4 persisted for approximately 7 years, and the beach profile had not returned to a similar morphology to those of stages 1 or 2 by the end of the study period. © 2018 John Wiley & Sons, Ltd.

Long-Term Observations of Beach Variability at Hasaki, Japan

“…In other words, the cyclone in 2006 may have changed the characteristics of the beach morphological changes, causing the foreshore to become steeper. The results are consistent with Kuriyama and Yanagishima [40] showing that the event caused regime shifts in the beach profile on the Hasaki coast. There was no clear difference in the mean profiles and S.D.…”

Influence of storm sequencing on breaker bar and shoreline evolution in large-scale experiments

“…Extreme storm events, such as storms peaking at high tide or storms of very large power, can generate severe erosion leading to an important change of the active beach profile (Kuriyama and Yanagishima, 2018). This relates, for instance, to erosion of the berm allowing subsequent waves to get further onto the beach resulting in an important narrowing of the beach width and possibly further erosion even under less energetic subsequent storms.…”

Changing Ocean, Marine Ecosystems, and Dependent Communities

“…The original dense vegetation is replaced by sparser vegetation (Zinnert et al 2019) and has a generally slow recovery (multiple years to decades) (Castelle et al 2017). In some instances, the changes persist over decades, resulting in a regime shift in the beach morphology (Kuriyama and Yanagishima, 2018). Such changes in vegetation and beach morphology in response to local disturbances were also related to shifts in the associated fauna composition (Carcedo et al 2017;Delgado-Fernandez et al 2019).…”