Rainwater Harvesting Seen as Solution for Drought and Flood Control

NAIROBI - Bitter irony: in recent years Nairobi has experienced severe flooding and widespread water shortages, due to poor urban planning and collapsing infrastructure systems that are failing to support the Kenyan capital's expanding population.

Large parts of the city are not properly served by water and sanitation infrastructure, particularly crowded areas like the Eastlands estates of Umoja, Makongeni and Doholm but also wealthier enclaves such as Karen and Langata.

At the same time, the rapid expansion of the city has led to sealing off of large surface areas, increasing the speed and volume of storm water run-off. Furious flooding exposes and damages water pipelines and chokes drainage channels with debris, spilling raw sewage into the streets.

David Mburu, chair of the Kenya Rainwater Association, says because there is too much surface cover, rain water is prevented from percolating into the ground. Some city residents who have opted for boreholes as an alternative to the intermittent water supply are now experiencing inadequate yields.

Mburu says there is a need to encourage both the harvesting of rainwater from buildings and directing run-off water into system of drains that would recharge the groundwater levels.

"Not all this water should be harvested and stored since we also need to recharge our groundwater levels by encouraging use of construction material that allows for seeping of run-off water into the ground or leaving as much surface that allows infiltration of water as possible," he says.

Peris Otachi, a resident of Kayole Estate, lost a brother in the 2001 floods, the worst experienced in Nairobi in recent years. "Flooding in Nairobi has become an annual ritual which unfortunately is never addressed by the city council or the government despite causing deaths and massive destruction."

Eleven people were killed by floods in Nairobi in 2001; while police cannot confirm the exact numbers, at least 21 more people have been drowned in flood waters since then. Otachi, whose younger brother's body was only found on the banks of the Nairobi River four days later, is now among residents who strongly believe that the floods can be controlled and the rainwater made better use of.

"It all starts with demystifying the rainwater harvesting technology," says Mr Stephen Mutoro."Let the people know it is within their reach to do it and its for their benefit in that they would reduce their water bills and access adequate water for non-potable use." Mutoro is the Executive Secretary of the Kenya Water and Sanitation Network (KWSN), a water consumers’ lobby group based in Nairobi.

"We need to create methods to capture rainwater as surface water is inadequate to meet demand in congested, over-paved metropolitan cities," says Professor Shaukat Abdulrazak, executive secretary of the National Council of Science and Technology.

A government statutory institute, the Council supports simple but effective rainwater harvesting methods as a solution to the over-paved city verandahs and streets. These include the installation of gutters to capture the roof water and setting up of underground storage tanks, especially by those putting up new homes and buildings.

How to get the process under way is a matter of some debate. Officials from the newly-created Nairobi Metropolitan Development (NMD) ministry, a new management structure for the greater Nairobi area, say rain water harvesting is to be enhanced to address the twin issue of flooding and water scarcity in the city of three million people, 75 percent of whom live in water-scarce slum and low income areas.

"We want to enhance effective rain water harvesting under an investment framework for water and sewerage services in the proposed metropolitan area in addition to managing metropolis’s water resource management capacity," NMD minister Mutula Kilonzo promised during the launch of the draft on the proposed metropolis by President Kibaki in January 2008.