Coastal River Dredging

Needs Address

Measures against storm surges, flooding, inundation

Adaptation effects

Can help reduce saline intrusion after flooding

Overview and Features

Dredging enhances the natural drainage ability of coastal rivers to unblock waterways and maintain their depth and therefore their drainage potential. Dredging also facilitates better drainage at times of flooding as well as to boost dry season flows to critical areas. 

Cost

• Equipment
• Labour
• The Bhulua River Re-excavation in Bangladesh, which took place from 1998-99 and from 2001-02 cost 1 million USD for each re-dredging (Agrawala et. al. 2003).

Energy source

• Fuel etc. for construction equipment
• Human resources 

Ease of maintenance

Depending on progress of siltation processes 

Technology performance

Over-dredging has in the past had adverse environmental consequences

Considerations

• Requires comprehensive management systems that incorporates understanding of inter-system processes to ensure dredging does not imbalance ecosystems further upstream
• Equipment requirements are determined by dredging needs e.g. the scale, and frequency of dredging
• Increased frequency of extreme events may demand increased reactive dredging rather than proactive efforts
• Planning processes must account for future likely climate processes and changes

Co-benefit, suitability for developing countries

• Improved  drainage facility
• Increased crop production
• Dredged sediment can be used for nourishment activities
• This requires appropriate equipment, resources and know how, hence   some institutional support to conduct at an effective level required

Information Resources

Agrawala, S., Ota, T., Ahmed, A.U., Smith, J. and van Aaist, M. 2003. Development and Climate Change in Bangladesh: Focus on Coastal Flooding and the Sundarbans. Organisation for Economic Co-operation and Development. Available at: http://www.oecd.org/env/cc/21055658.pdf [04 December 2014

CEDA, 2012. Climate Change Adaptation as it Affects the Dredging Community. Central Dredging Association Position Paper. Available at: http://www.dredging.org/documents/ceda/html_page/2012-05-ceda_positionpaper-climatechangeadaptation.pdf [04December 2014]

Yun, C. 2007. A New Era of Win-win Cooperation. Western Dredging Association. Available at: https://westerndredging.org/index.php/woda-conference-presentations/category/56-session-2d-sediment-management [07 April 2015]