TY - JOUR
T1 - Can cheniers protect mangroves along eroding coastlines?
T2 - The effect of contrasting foreshore types on mangrove stability
AU - van Bijsterveldt, Celine E.J.
AU - van der Wal, D.
AU - Gijón Mancheño, Alejandra
AU - Fivash, Gregory S.
AU - Helmi, Muhammad
AU - Bouma, Tjeerd J.
N1 - Funding Information:
This work is part of the BioManCO project with project number 14753, which is (partly) financed by NWO Domain Applied and Engineering Sciences, and co-financed by Boskalis Dredging and Marine experts, Van Oord Dredging and Marine Contractors bv, Deltares, Witteveen+Bos and Wetlands International. Furthermore, the authors are grateful for the skills of the drone pilots Faiz Hamzah Adriono and Bagus Rahmattullah Dwi Angga and their dedication to fly the drone in a very challenging environment. We are grateful to Pak Slamet and Ibu Paini for providing us with a home during the demanding fieldwork periods, where Pak Muis' skills as a translator were greatly appreciated. The authors would also like to thank Annette Wielemaker for her helpful assistance with the GIS analysis. Finally, we are grateful to Peter Herman, Bas van Maren, Ad Reniers, Silke Tas, Wim Uijttewaal, Bregje van Wesenbeeck and Han Winterwerp for the many fruitful discussions on chenier dynamics and chenier-mangrove interactions.
Publisher Copyright:
© 2022 The Authors
PY - 2023/2
Y1 - 2023/2
N2 - Mangrove forests are increasingly valued as wave-attenuating buffers in coastal flood defence strategies. However, as mangroves are vulnerable to wave-induced erosion, this raises the question, how can the stability of these protective mangrove forests be promoted? To address this question, we investigate how mangrove dynamics in a microtidal system can be related to different types of foreshores. We used remote sensing to investigate mangrove fringe stability over multiple years in relation to intertidal mudflat width (i.e., emerged at low tide) and the presence stability of cheniers, which are sand bodies on top of muddy foreshores that are characteristic for eroding coastlines. In addition, we investigated local and short-term foreshore effects by measuring wave propagation across two cross-shore transects, one with a mudflat and chenier and one with a deeper tidal flat foreshore. The satellite images (Sentinel-2) revealed that mangrove dynamics over multiple years and seasons were related to chenier presence and stability. Without a chenier, a mudflat width of 110 m (95%CI: 76–183 m) was required to make mangrove expansion more likely than mangrove retreat. When a stable chenier was present offshore for two years or more, a mudflat width of only 16 m (95%CI: 0–43 m) was enough to flip chances in favor of mangrove expansion. However, mangrove expansion remained heavily influenced by seasonal changes, and was highly event driven, succeeding only once in several years. Finally, although mudflat width was a direct driver of mangrove expansion, and could be targeted as such in coastal management, our field measurements demonstrated that cheniers also have an indirect effect on mangrove expansion. These sand banks significantly reduce wave height offshore, thereby likely creating favorable conditions for mudflat accretion landward, and thus mangrove habitat expansion. This makes stabilization - and possibly also the temporary creation - of cheniers an interesting target for mangrove conservation and restoration.
AB - Mangrove forests are increasingly valued as wave-attenuating buffers in coastal flood defence strategies. However, as mangroves are vulnerable to wave-induced erosion, this raises the question, how can the stability of these protective mangrove forests be promoted? To address this question, we investigate how mangrove dynamics in a microtidal system can be related to different types of foreshores. We used remote sensing to investigate mangrove fringe stability over multiple years in relation to intertidal mudflat width (i.e., emerged at low tide) and the presence stability of cheniers, which are sand bodies on top of muddy foreshores that are characteristic for eroding coastlines. In addition, we investigated local and short-term foreshore effects by measuring wave propagation across two cross-shore transects, one with a mudflat and chenier and one with a deeper tidal flat foreshore. The satellite images (Sentinel-2) revealed that mangrove dynamics over multiple years and seasons were related to chenier presence and stability. Without a chenier, a mudflat width of 110 m (95%CI: 76–183 m) was required to make mangrove expansion more likely than mangrove retreat. When a stable chenier was present offshore for two years or more, a mudflat width of only 16 m (95%CI: 0–43 m) was enough to flip chances in favor of mangrove expansion. However, mangrove expansion remained heavily influenced by seasonal changes, and was highly event driven, succeeding only once in several years. Finally, although mudflat width was a direct driver of mangrove expansion, and could be targeted as such in coastal management, our field measurements demonstrated that cheniers also have an indirect effect on mangrove expansion. These sand banks significantly reduce wave height offshore, thereby likely creating favorable conditions for mudflat accretion landward, and thus mangrove habitat expansion. This makes stabilization - and possibly also the temporary creation - of cheniers an interesting target for mangrove conservation and restoration.
KW - ITC-ISI-JOURNAL-ARTICLE
KW - ITC-HYBRID
U2 - 10.1016/j.ecoleng.2022.106863
DO - 10.1016/j.ecoleng.2022.106863
M3 - Article
SN - 0925-8574
VL - 187
JO - Ecological engineering
JF - Ecological engineering
M1 - 106863
ER -
