Assessment of the potential of bioengineering intervention for retarding cyclonic wind and storm surge in coastal Bangladesh

Abstract

Bioengineering is the technique of using live materials – particularly vegetation to provide engineering solutions. Nature-based, eco-friendly, and flexible solutions are being widely explored around the world as we strive for sustainability. Bioengineering strategies have demonstrated their effectiveness in mitigating natural hazards such as soil erosion and cyclonic effects in different parts of the world, particularly in East Asia, Europe, and the Americas. The artificial intervention measures using hard engineering strategies rely heavily on concrete and steel for protection from natural hazards, which is expensive and difficult to reliably maintain for the developing countries with smaller economic might. An expansion of bioengineering in these countries can provide an effective and economically feasible solution to coastal protection. Bangladesh is frequented by tropical cyclones almost every year due to the geographical positioning of the country. The Western Coastal Zone of Bangladesh is protected by a buffer zone in the form of the Sundarbans mangrove forest. However, the Central Coastal Zone is with minimal buffer and virtually exposed to the Bay of Bengal, while the Eastern Coastal Zone is with moderate strip elongated mangrove covers. In this thesis, the potentiality of bioengineering in the context of coastal Bangladesh has been explored. The mixed research methodology has been utilized, using both Primary and Secondary Data, and the collected data has been synthesized and interpreted to come to a conclusion. It has been established by NDVI analysis of the Coastal Zone of Bangladesh between the years 1990 to 2020 that the Central Coastal Zone has traditionally lacked dense vegetation. However, an increase in the vegetation extent and density has been observed through the data analysis that indicates the positive effects of the recent afforestation initiatives. The analysis of Wind Speed and Water Level data has established that the gauge stations which are located around the mangrove cover consistently experience lower wind speed and lower water levels during cyclonic events compared to the stations exposed to the coast. This effect has also been found to be pertinent in the case of storm surges for specific cyclonic events where the stations with mangrove cover generally recorded lower storm surges except for cases when the landfall was nearby. Semi-Structured Interviews had been carried out to extract primary data and the data has been analyzed to gather the perception of the local people and interpret their attitudes towards an expansion of bioengineering measures. Through the synthesis and interpretation of the data, it has been found that there is widespread recognition among the local coastal residents about the beneficial effects of a forest buffer at the coast. However, through primary data analysis, the issue of land stress has been found to persist in such a densely populated country as Bangladesh. Nevertheless, there is a potential for adopting a strategically designed policy incorporating soft engineering methods in conjunction with hard engineering methods to protect the coastal area from natural hazards such as cyclones, under a framework of Integrated Coastal Zone Management, which will be socio-technically, environmentally, and economically beneficial in the context of coastal Bangladesh.