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A time to (water) harvest: The data behind Kenya’s impending water crisis

By Purity Mukami

The rainy season can be a frustrating time in Kenya. Flooding in Mombasa and Narok. Backed up drains in Nairobi and the threat of Cholera in Naivasha. Add to that, almost all that water, running into rivers and into the Indian Ocean. It is even more frustrating if you think that this water won’t be available to you in a couple of weeks time. I know it frustrates me.

One day, while I was stuck in hours-long traffic on the Thika superhighway, and in a deluge, I got so frustrated that I did the math on the amount of water that was furiously raging through the town, getting lost.

Assume that Thika road is one straight highway, off of which Kenya decides to harvest water.

Thika Road is 50km long. Assume also that the 8 lanes is equivalent to about 12 meters wide. Then the surface area of the superhighway would be 600,000 square metres. If there is a drizzle of 10mm, the amount of water that would run over the superhighway would be; 6,000,000 litres of water, or 6000 cubic metres of water. This is enough water to sustain 60, 000 individuals who use about 100 litres (5 20-litre-containers) per day.

According to the above graph, Thika station received total rainfall of about 25 mm between 5th and 11th March this year. So, we could have collected 12,000,000 litres of water, putting into consideration 20% water loss from evaporation and absorption. That’s enough to sustain 120,000 Kenyans using 100 litres for one day.

If you consider areas around Kabete weather station that received a total rainfall of 100.6mm the same week, and take surface area of 50,000 by 12 meters, 48,288,000 litres of water just ran through to the nearby river, with some of it finally winding up in the ocean. Putting together amounts from major highways such as Mombasa road, Ngong road, the southern bypass, northern bypass, Outer ring Road, Langata road etc., we likely lost somewhere in the tens of millions of litres of water. If we take the entire Nairobi County which is 696,000 sq., and take the rainfall to be an average of 50mm within 24 hours, about 27,840,000 litres of water go to ocean every day it rains;11% of the 200 000  cubic metres of Nairobi’s daily water deficit. Coming close home , if you utilize a quarter of an acre of land to collect rainwater,  out of 50mm within 24 hours one would collect (50mm*1011.714 sq. m*0.8 after a loss of 20 %) 40,468.56  litres of water.

A 10,000-litre salty water tank would cost about KSH 2500 hence one day’s collection of rain water would save one about KSH. 10,000. However, a 10, 000 litre water tank would cost KSH 70,000. So, it would cost an individual about KSH. 280,000 to buy four tanks each of 10, 000 litres capacity collecting the water from a quarter acre ground surface. So for the 36% of Kenyans who are defined as poor by the Kenya National Bureau of Statistics most recent household study, it would be difficult to imagine harvesting a substantial amount of water to use during the dry season; unless of course the government was to subsidize the cost of water harvesting. Even then, it would be tough.

Water deficit and scarcity is likely to become a major global, regional and communal cause of conflict, or a compelling driver to war.

For the past three years, hundreds millions of shillings have been set aside either for drought or flood mitigation. Most recently, Mike Mbuvi Sonko, Nairobi’s Governor, set aside Ksh. 194 million for flood mitigation. It is unlikely that even part of the money was used for research; design and building of sustainable water harvesting systems. Yet, therein may lie Nairobi’s, and Kenya’s answer to its water problems.

In the video below, architect Judy Kebenei, a green architecture enthusiast, claims that building greener roofs and pavements would considerably reduce flooding by absorbing some of the water that runs off the hard surfaces many roofs are made of.

The Rwanda genocide memorial park in Kigali, and the Coca Cola building in Upper Hill, Nairobi, among others, use the building principles that Kebeneni describes.  She also says that drainage systems designed for recycling of the rain and wastewater would reduce floods and the water shortage that is usually experienced after the rains end.

As evidenced in Africa Uncensored’s recently published environmental series, End of the River, water deficit and scarcity are likely to become a major global, regional and communal cause of conflict, or a compelling driver to war. Worldwide, about two out of every three people live in areas that face serious freshwater shortages according to UNESCO. Population growth, irrigation projects, industrialization and effect of climate change have been pinned as key causes of water shortages.

Nairobians and Mombasa city dwellers will access one tenth of their water requirement. Simply put; if you will need 100 litres a day, you will only be able to access 10 litres

In Kenya, a multi-sectorial study that was done by JICA (Japan International Cooperation Agency) for over 3 years, concluding in October 2013. It showed that there was already a 44% water deficit- that is 1,418 million cubic meters per year, of water that could not be met. The Athi Catchment area, where the country’s major cities Nairobi and Mombasa lie recorded the highest deficit of 65%. By November 2014, Nairobi was facing a water shortage of 250 million litres according to the report that was presented to the then Water and Irrigation cabinet Secretary Eugene Wamalwa.

According to the JICA report, by 2010, half of Kenya’s water was being used for irrigation. It is estimated that this will rise to 84 % in the year 2030. If the rate of climate change does not slow down, only 2 % of the available water may be left for livestock and 12% for domestic use in Kenya.

With rural-urban migration expected to double by 2030, major irrigation schemes listed in Kenya’s Vision 2030 economic blueprint, and the 127,277 acres currently under irrigation according to the National irrigation Board expected to be implemented fully, the deficit is expected to rise to 70% countrywide and to 91% for the catchment area that harbors the two major cities in Kenya. This means that Nairobians and Mombasa city dwellers will access one tenth of their water requirement. Simply put, if you will 100 litres a day, you will only be able to access 10 litres.

This is because, according to the Vision 2030 blueprint, Kenya plans to irrigate 100,000 hectares of land annually to achieve its 1,000,000-acre goal of irrigated land by 2030, starting with the Galana Kulalu national food security project. Already, that scheme is facing its own challenges with low crop yields. This is in addition to the major irrigation schemes that add up to 43,271 acres under irrigation in Mwea, Ahero, West Kano, Bunyala, Bura and Perkerra and 127,277 acres irrigated in various projects in 34 out of the 47 counties. Turkana County leads with 29,900 acres under irrigation followed by Baringo with 15,400 acres. Ironically those are among the counties that quite often face food shortage during the dry season. This video gives you a background of all of Kenya’s irrigation schemes, versus Kenya’s food insecurity challenges.

Could Kenya’s water insecurity lead to conflict? The signs from other water scare areas certainly point to this possibility, as evidenced by animosity among neighboring countries. They have had difficulties in agreeing on how to use their shared water bodies such as Lake Victoria, the river Nile, Zambezi river and river Niger sustainably.

According to the JICA report, by 2010, half of Kenya’s water was being used for irrigation. It is estimated that this will rise to 84 % in the year 2030. If the rate of climate change does not slow down, only 2 % of the available water may be left for livestock and 12% for domestic use in Kenya.

Back to my own  domestic maths. While all the rain water is furiously running to the nearby rivers and more irrigation schemes are being implemented , a study of supply of water to the 12 apartment units where I live, (I’ve had the same neighbours for the last 5 years) showed  that the  water  deficit started hitting middle class town dwellers early in 2017. This is when water supply to each home drastically decreased  by half on average, and the price per one unit (1000 litres) of water  increased by about 55%. This is despite the fact that family sizes have grown from two people to at least four on average. Most of us now rely on less than 10,000 litres per month, whereas some of us lived on  more than 15,000 litres when we moved in five years ago.

This literally means that most of us either have to halve the amount of water used for various activities such as cleaning clothes, flushing the toilet, washing utensils, hand washing and cleaning the house, or buy more water. Even that option may not be available in a few years. Worse than sitting in traffic on a rainy day, Kenya is facing a day when it will miss its water altogether.

The Calculations

Thika Road is metres long. Assume also that the 8 lanes are equivalent to about 12 meters wide. Then the surface area of the superhighway would be

Thika station received a total rainfall of about 25 mm between 5th and 11th March this year, so we could have collected 25*600,000*0.8=12,000,000 litres of water=12,000,000 litres, putting into consideration 20% loss of the water.

If you consider areas around Kabete weather station that received a total rainfall of 100.6mm the same week, and take surface area of 50,000 by 12 meters, litres of water.

If you utilize ¼ acres of land to collect rain water, of 50mm within 24 hours one would collect 50mm*1011.714 sq. m*0.8 after a loss of 20 % = 40,468.56 litres of water.

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About the Author
Purity Mukami is a Statistician and University Lecturer. She is a data analyst at Africa Uncensored.
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