The floods were the worst in decades

Accra’s flooding episodes have become complicated, leaving policymakers confused.

Fortunately, research by the Department of Civil, Geo Environmental Engineering at the Technical University of Munich has proposed a retention basin for reducing Accra flood risk.

The basin will temporarily store the water and then be discharged purposely downstream. 

Flood analysis by the research team showed the overall reduction of flood risk by 28%. In monetary terms, this translates to a yearly risk reduction of about €5 million.  

In this respect, the European commission and water (UEC, 2003) recommend, among others, an integrated river basin approach and the retention of water.

Using rainfall data from 1980 to 2017, the research team simulated the best option for a retention basin in the Odaw-Korle Catchment.

The basin, estimated to cost about €50 million, was simulated with a 6.82 million metric cubed of water.

It is designed to close at the bottom outlet in the case of flood and the discharge managed up to the design event for a 100-year return period.

If the flood is heavier than the design event, the water will be released through a spillway.

The study yet to be published is significant in supporting efforts by the Ministry of Works and Housing to implement the 2021 National flood control programme and the Accra City Resilient Plan launched by the AMA in 2019.

However, the findings have been subjected to internal validation using an almost similar basin built in Germany in 2009 at about the same cost.

The Study was undertaken by Benedikt Bauer as part of an MSc programme.

The supervisors were Prof. Dr Ing Markus Disse and Qing Li (MSc), both of the Technical University of Munich, Germany. Professor Dr Jorge Eduardo Leandro of University Siegen, Germany and Professor Divine Ahadzie, Centre for Settlements Studies, KNUST.