4 minute read
Mubarraz Island
Mubarraz Island, Abu Dhabi, United Arab Emirates
Planting mangrove habitat for shoreline protection. Offshore of Abu Dhabi in the Arabian Gulf, Mubarraz Island has faced increasing shoreline erosion. In the 1980s, an international oil company initiated the beneficial use of 12 million cubic meters of dredged seabed material from a channel-dredging operation for the construction of a causeway on the island to protect oil pipelines and serve as a road connection. For environmental enhancement and protection from erosion, mangrove habitats were created along the shorelines of the causeway. Over a 35-year period, more than half a million nursery-raised mangrove seedlings were planted annually. Initial plantings focused on environmental enhancement and were successful in only sheltered corners of the causeway. Since 2009, a new Engineering With Nature (EWN) approach has been adopted by creating artificial tidal channels that are excavated parallel to the causeway and planted annually with tens of thousands of seedlings. Because of the innovative approach and persistent planting over many years, mangrove vegetation has been successfully established along nearly seven kilometers, or approximately 20%, of the causeway’s shorelines, with new plantings along an additional nine kilometers underway. For this use of EWN approaches, the project was awarded a PIANC Supporter of Working with Nature certificate in July 2021.
Article Cover: The Mubarraz Island mangrove plantation along the excavated causeway, which was created from beneficially used dredged material. (Photo by Abu Dhabi Oil Co. Ltd [Japan] [ADOC Japan])
Producing Efficiencies
A nature-based solution using planted mangroves was adopted to protect shoreline erosion along the causeway. Artificial tidal channels, running parallel to the causeway, were created for the specific purpose of providing suitable habitat for the mangroves while leaving a protective barrier of dredged material between the channels and the sea. Ultimately, once the sea has eroded the barrier of dredged material, the mangroves behind it will have established successfully and grown into mature stands capable of resisting the hydrodynamic forces of tides and waves to effectively protect the causeway from further erosion.
Using Natural Processes
The entire causeway was built from beneficially used dredged material. The tidal channels were subsequently excavated within this dredged material to a depth known to result in tidal inundation characteristics conducive to the growth of Avicennia marina (gray mangrove). Because of their dense and extensive network of stems, pneumatophores, and cable root systems, the mangroves are able to protect the shorelines from erosion through attenuating wave energy and binding and trapping sediments, thereby contributing to the protection of critical oil pipeline infrastructure. Mangrove planting activities at Mubarraz Island have been highly successful and continue to this day.
Broadening Benefits
The mangroves have attracted significant biodiversity over the years, including more than 60 bird species and an assortment of gastropods, crabs, and fishes. With the ability to self-repair and maintain, mangrove plantings have proven to be a significantly cheaper and more sustainable solution to shoreline protection than conventional engineering approaches. Costs of mangrove planting were five- to tenfold lower than the costs of sheet piling or other hard engineering solutions. This project demonstrated that planting mangroves on dredged material was feasible, even under extreme climatic conditions, offering a costeffective, low-maintenance, and sustainable solution for shoreline protection, with added benefits for biodiversity conservation.
Promoting Collaboration
This project demonstrated that it is feasible for an oil company to operate responsibly within a wider marine protected area by working closely together with environmental authorities and international experts over a multidecadal time scale to preserve and significantly enhance environmental values in a climatologically extreme region. Internal mangrove planting work procedures were drafted, and staff that were trained in nursery and planting techniques persisted year after year to plant hundreds of thousands of mangrove seedlings, learning along the way from successes and failures, resulting in more than 17.5 hectares of healthy mangrove stands in various stages of maturity.
