Bamboo Fences as a Nature-Based Measure for Coastal Wetland Protection in Vietnam

Cong Mai Van,Anh Ngo,Tri Mai,H T Dao

doi:10.3389/fmars.2021.756597

Abstract

Climate change has induced sea-level rise and a high intensity of storms, which create high nearshore waves. These caused severe mangrove degradation and erosion along the coastal wetland areas in the Mekong Delta in Vietnam. Mangroves in the coastal wetland foreshore can withstand only some certain design storm waves and grow under several certain submerged conditions. Therefore, reducing waves and shallowing wetland elevation for recovering mangroves and protecting them in an early birth state is important. Bamboo or melaleuca fences have been used as a nature-based solution to reduce waves and currents approaching the shore for these above purposes along Vietnamese Mekong deltaic coasts. This paper investigates wave transmission through the bamboo fence system and assesses its effectiveness in protecting the mangroves. Waves were simultaneously measured at two locations for comparison: in front of and behind the fences. The result shows that the wave reduction by the fences is considerable, and sedimentation occurs rapidly in the shelter areas behind the fences, which is highly favorable for the recovery and growth of mangroves. Next, the empirical formulae have been proposed for relationships between the wave transmission coefficient of the fence and the dimensionless wave-structures parameters, such as the relative water depth, the wave steepness, and the fence freeboard. The findings create a basic technical reference for designing a naturally friendly-based solution by using bamboo and/or wooden fences in coastal protection generally and protecting mangroves specifically. The outcome of the research contributes to narrowing an existing gap in Vietnamese design guidelines for coastal wetland protection and also facilitates the use of locally available eco-friendly materials for coastal management along the Vietnamese Mekong delta coasts.

Highlights

Coastal regions are historically the most densely populated areas globally, which benefit from the open ocean and provide inputs for economic development, such as navigation, coastal industries, tourism, and recreation
Coastal regions are increasingly threatened by the sea-level rise and coastal hazards, such as intense storm surges and hurricanes
This paper analyzes the observed data from a practical model for mangrove planting to understand the efficiencies of a wooden fence on waves reduction and transmission at the coastal area in Nha Mat ward, Bac Lieu city, Vietnam

Summary

INTRODUCTION

Coastal regions are historically the most densely populated areas globally, which benefit from the open ocean and provide inputs for economic development, such as navigation, coastal industries, tourism, and recreation. Hard solutions to prevent coastlines sensitive to the sea-level rise become more prevalent. In the Mekong deltaic coast, the reduction of mangrove forests has been even more serious/severe since the combination of sea dikes and aquaculture, such as shrimp ponds, is presented along the coastal area. The mangrove belt systems used for reducing waves and currents to protect coastlines and sea dykes were investigated and presented in Mazda et al (1997). This paper analyzes the observed data from a practical model for mangrove planting to understand the efficiencies of a wooden fence on waves reduction and transmission at the coastal area in Nha Mat ward, Bac Lieu city, Vietnam. Sedimentation in the researched area has been observed and will be analyzed and presented in this paper

METHODOLOGY

RESULTS AND DISCUSSIONS

CONCLUSIONS AND RECOMMENDATION