Ghana must rethink drainage systems or face worsening floods — GhIE warns

The Ghana Institution of Engineering (GhIE) has called for an urgent overhaul of the country’s stormwater management policies.

They warned that the country’s current drainage systems were no longer capable of addressing the realities of rapid urbanisation, climate variability, and increasing flood risks. 

The call, which was in a statement copied to the Ghana News Agency in Accra on Monday, followed growing evidence that conventional drainage infrastructure, designed primarily to move stormwater downstream as quickly as possible, had become inadequate for modern urban environments, particularly in Accra and other rapidly expanding metropolitan areas. 

A policy brief presented by the institution stated that Ghana’s cities can no longer rely on traditional, centralised, conveyance-based drainage systems.

“Rapid urban expansion, widespread paving of land surfaces, poor waste management practices, and increasing rainfall intensity have significantly exceeded the capacity of existing drainage networks. 

“Flooding in Accra is no longer simply a seasonal occurrence. It is increasingly becoming a structural challenge driven by rapid urbanisation, loss of natural infiltration areas, and fragmented management systems,” the policy brief noted. 

The institution observed that flooding incidents had become more frequent and severe over the past decade, occurring even during periods of relatively low rainfall.  

“This suggests that the problem extends beyond climate change and reflects deeper weaknesses within existing stormwater management systems.” 

The institution highlighted that many drains had effectively become conduits for solid waste, reducing hydraulic capacity and compromising their intended function.  

The policy brief also noted that hydraulic constraints within the Odaw-Korle drainage system continued to contribute to recurring flood events across parts of the capital. 

The document identified institutional fragmentation as a major obstacle to effective flood management. 

“Responsibilities are spread across multiple agencies, while administrative boundaries often do not align with natural drainage basins, making coordinated catchment-wide planning difficult.” 

To address these challenges, GhIE is advocating a transition towards decentralized, nature-based stormwater management systems that mimic natural hydrological processes.  

Recommended interventions include permeable pavements, bioswales, rain gardens, green roofs, detention systems, infiltration facilities, riparian buffers, and rainwater harvesting. 

The institution is also calling for a national post-development runoff control policy to ensure that new developments do not generate runoff volumes and peak flows beyond pre-development conditions. 

In addition, GhIE recommended a national rainwater harvesting policy, stronger enforcement of land-use regulations, catchment-based planning units, protection of waterway buffer zones, and greater private-sector participation in green infrastructure development. 

According to GhIE, adopting these measures could significantly reduce flood frequency and severity, improve water quality, lower long-term infrastructure costs, create green jobs, and strengthen Ghana’s resilience to climate change. 

“The evidence is clear,” the report concludes. “Ghana must shift from downstream, conveyance-based engineering to upstream, decentralised, nature-mimicking stormwater management. The time for policy reform is now.” 

The recommendations aligned with the best global practices in sustainable urban drainage and support the achievement of the United Nations Sustainable Development Goals, particularly SDG 6 (Clean Water and Sanitation) and SDG 11 (Sustainable Cities and Communities). 

المصدر: MyJoyOnline (GH)