Saving the ecosystem: Engineered Wetlands - a sustainable solution for mangrove depletion

Apart from planting mangroves, we need to address reason for their decline.

KARACHI: To preserve mangroves, we need to do more than just plant them - we need to address the reasons for their decline and achieve a long-term solution.

The social, economic and environmental importance of the mangrove forests and their threatened status in Pakistan is well-established. Most of the conservation projects that have been initiated so far have focused on planting mangroves and raising awareness among the communities. While planting additional mangroves may contribute to a short-term increase in the vegetation cover, a failure to tackle the underlying reasons for their decline would mean that long-term benefits are not achieved.



Major threats to the mangrove forests include pollution, human exploitation and lesser availability of fresh water in the crucial mixing zones where the mangroves survive. To redress this negative development, we need viable measures to remove these threats.

One such measure is to use the opportunities provided by nature - using wetlands as a ‘pollutant filter’ to cleanse polluted domestic sewage. Along the Karachi coastline and beyond, most of the mangroves have been cleared to make way for boating marinas. The dense mangrove cover is now only available across the coastline in the creek system.

Ecotone wetlands

One possible approach to sustainably protect these threatened mangrove ecosystems could be the development of ‘Ecotone Wetlands’ or artificial wetlands along the coastline. The sewage of the village can be collected and transferred to a specially designed wetland, where some species of indigenous sub-semi arid forest variety that can be used for fodder orfuel wood are planted. The sewage can be channelled sub-surface into the wetland to provide nutrients to the plantations and thus a unique combination of marine plus terrestrial and natural plus constructed ‘Ecotone Wetland’ can be operated.

With the availability of alternative sources of fuel wood and fodder, a reduction in pollution load, the mangroves will benefit. The local community, particularly women, who can be the main focus of the capacity-building process, will be trained in sustainable resource use.

Ecological engineering

The project will be based on the concept of ‘Ecological engineering’, which relies on the nature’s ability to self-design a self-sustaining ecosystem. Even within Karachi, such an experiment can be done along the backwater areas. This will also help treat sewage and can be extended to create a recreational facility. Since such a project offers an integrated approach, the community can also benefit along with the ecosystem.

A major cause of diseases in such coastal communities is improper sanitation. Once sewage is collected, transferred and treated, and then disposed off in a proper manner, the neighbourhood’s condition will improve. Subsequently, the health of these residents and their savings will also get better. Another short-term improvement that the residents will see is an improvement in financial condition as they will find employment in the project to develop this ‘Ecotone Wetland’. This will reduce the level of exploitation of the mangrove ecology. Since the mangroves act as nurseries for a variety of aquatic life, especially shrimps, the survival of the mangroves indirectly gets translated into financial benefits for the fishing community, as well.

The writer is an urban planner and runs a non-profit organisation based in Karachi city focusing on urban sustainability issues. He can be reached at [e-mail]

Published in The Express Tribune, December 9^th, 2013.