Quick solutions to Kampala flooding

By Daniel Opwonya

The numerous flooding events in Kampala show how land use management in the city has gone terribly wrong. Although most critics blamed KCCA, I think, collectively all the city dwellers bear some degree of responsibility.

Floods in Kampala are mostly rainstorm induced; meaning that understanding the interactions between the rainfall and the pathway the rainwater takes gives insights into finding solutions.

Kampala receives heavy rainstorms and when this is coupled with its hilly topography, not enough time is available for rainwater to infiltrate into the ground. Also, the increased use of impermeable surfaces like roofs and paved compounds quickly gather this rainwater and accelerates it to the streets which are themselves connected to either insufficient or blocked drainage channels or into low lying areas that comprise of destroyed wetlands whose infiltration and storage capacity have been significantly reduced. Hence what starts out as small puddles soon grow into fully-fledged flooded streets, therefore, making storm water management for Kampala city challenging. 

With this background, here are few quick fix solutions that, if implemented over the short-term, would significantly reduce the flooding in three to five years. These proposed solutions are only meant to arrest the situation for now while giving time for KCCA to engage experts for the more complex mid-term to long-term soft and hard solutions. 

First of all, let us think rainfall harvesting. Rainwater can be harvested from building roofs into tanks for sanitary use or soak pits for ground water recharge. It may be difficult to comprehend how a few buckets of rainwater from one roof can ease the flooding situation in Kampala.

Well, it is all about the numbers. If for example; you, your neighbours, malls, schools and hospitals start to harvest rainwater, the overall amount allowed to reach the streets at the same time is significantly reduced and by reducing the maximum flow rate, one reduces the potential for most floods to occur. In this regard, therefore, low cost gutters must be made available and enforced in construction.

Similarly, compound paving using solid pavers or tarmac should be changed to hollow pavers to allow for natural infiltration at homes and commercial buildings. In Germany, for example, city authorities charge property owners for every square meter of hard surface in one’s compound in an effort to reduce rainwater coming from these properties onto the streets.

Secondly, KCCA needs to create more green zones or work with the management of existing ones like Kampala-Golf Club, Kyadondo Rugby Grounds etc. for these areas to be re-designed to harvest or act as temporary retention basins for flood water during peak rains; after all, these kinds of extreme flooding as experienced last Friday are considered to have five to 10-year return periods meaning that the damages to these grounds can be minimal, if these grounds were utilised..

Thirdly, better management of rubbish and the control of the amount of sand from construction sites entering the drainage channels are very important because these block and therefore impede storm water. The obvious choice would be to demolish all buildings in wetlands, but as we all know, this is nearly impossible due to the power-money dynamics involved. So, win-win solutions that do not necessarily involve huge investments or demolition of buildings are your best bet on reducing the flooding situation in such a complex social-economical and environmentally challenged city like Kampala.

The writer is a water engineer