November 23rd 2017

Society / Environment

Nairobi's water crisis easy to redress if we get priorities right

By increasing the number of trees in parks and including them in infrastructure, Nairobi will experience increased rainfall which will consequently increase the water supply. Additionally, trees provide shade, they reduce soil erosion, and they increase the drainage of surface runoff.

By Angeline Mbogoangelinejaymz@gmail.comSaturday, 14 Oct 2017 15:51 EAT

The Ndakaini Dam, Nairobi's main water source.

Water supply challenges in Nairobi go as far back as the 1970s. Water supply is 20 percent below overall demand. What’s more, according to the World Population Review, the Nairobi population has grown by 3.402 million since 2009 bringing the current population at about 6.54 million. That is to say that the water demand is increasing annually while efforts to increase water supply remain minimal.

Thika Dam provides 430,000m3 per day of water to Nairobi residents. This amount accounts for 84 percent of the total water supply for Nairobi residents. The remaining 16 percent is catered for by groundwater and rainwater. According to a University of Nairobi domestic water consumption case study in 2001, the per capita water consumption for Nairobi residents is about 0.119 m3 per day. Therefore, with the total water supply standing at about 570,000m3 per day, it is correct to state that the water demand in Nairobi is higher than the water supply even without factoring in industrial and commercial water consumption.

With this in mind, one can see the danger that the Nairobi residents will experience in the future if the water supply is not increased to meet the constantly growing demand.

Nairobi relies on other counties for most of its water supply. While dependence is not necessarily a bad thing, the capital city has overlooked potential water sources such as its rivers. Rivers are a reliable source of water but only when clean. Unfortunately, Nairobi County boasts several polluted rivers that were once uncontaminated and a source of water for the nearby villages.

These villages developed into slums and the rivers were polluted as the slum population increased. So while the residents of slums such as Mathari, Korogocho, Mukuru and Kibera would be relying on the Mathari and Ngong River for water, they have to rely on water kiosks and groundwater. The Nairobi River which is also polluted denies residents of Dandora, Kariobangi South, and Shauri Moyo of a potential water source. What’s more, if the Nairobi River were to be rehabilitated, it would not supply sufficient water since its volume has been greatly affected by urban development.

Another potential water source is the Nairobi Dam which has a storage capacity of 98,000m3. Regrettably, it is polluted and currently is covered with hyacinth.

Furthermore, rainwater harvesting is a potential water source for Nairobi residents. Yet, this option has been largely ignored. This is disappointing because a lot of tenants have to endure water rationing, a practice that would be unheard of if rainwater was harvested. Until rainwater is harvested both in small scale and large scale, Nairobians will continue to suffer losses from floods during the heavy rains.

Boreholes are popular throughout Nairobi County. There are about 3,500 known boreholes while another 40 were added by the County Government in 2016 to increase water supply. Nevertheless, the use of groundwater needs to be controlled. Aquifers can take a century to recharge which means that restricting the overexploitation of groundwater is necessary.

According to the Water Act 2002, any person wishing to drill a borehole should first seek permission from the Water Resources Management Authority. The reason why a permit is required is to ensure that a site is suitable for groundwater abstraction.

Rainwater is important because it recharges surface and groundwater sources. On the other hand, forests are important in the capturing of rain. As a result, while forests such as Karura, Aberdare, and Olulua need to be conserved, urban forestry should be increased as well.

By increasing the number of trees in parks and including them in infrastructure, Nairobi will experience increased rainfall which will consequently increase the water supply. Additionally, trees provide shade, they reduce soil erosion, and they increase the drainage of surface runoff.  

The rehabilitation of polluted rivers may prove expensive and complicated, but it can be done. Pushing developers to include rainwater harvesting structures on the rooftops of buildings can go a long way in increasing the water supply. Urban forestry will not only contribute to increased rainfall but also enhance aesthetics and reduce floods.

In a nutshell, while it is obvious that there is a water demand-supply gap in Nairobi that needs to be bridged and there are solutions, the future will depend on how these solutions are prioritized.

The writer is a graduate physical/urban planner with a love for writing





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