Why Map Open Drainage? And How?

by: April 4th, 2011 comments: 3

Open Drainage

I believe that the reasons to map open drainage in the slums are well known and are obvious to most people. Everyone who’s ever been to the slums knows that open drainage presents a huge health hazard to the people living around it. In combination with poor or non-existent water and sanitation systems, open drainage presents a recipe for disaster which is always present and can erupt at any time and wreak havoc amongst the populations. If I quote a few experts on the dangers that open drainage poses:

“Potholes in the streets, pools of stagnant water, and waste gushing from bathrooms and kitchens provide breeding sites for malarial mosquitoes and other spreaders of disease.” (Nwaka, Geoffrey I. “The Urban informal Sector in Nigeria”)

“Most slum households must fetch their water from a standpipe and deposit their waste in open drains. The rate of infection is high; therefore there is constant risk of epidemic.” (Gulis et. Al. “Health status of people of slums in Nairobi, Kenya”)

“In slum areas, a minor flood is not just inconvenient. It is life-threatening. With open drains and overflowing latrines even a small flood means that children have to wade through raw sewage.” (Willem Alexander, HRH, Chair of UNSGAB. “World Water Day Op Ed”)

In an article on the health status of people of slums in Nairobi, Kenya the authors conclude that: “Environmental conditions can have major influences on health status. Therefore, environmental improvements are important in the improvement of health status.” (Gulis et. Al. “Health status of people of slums in Nairobi, Kenya”)

As my friend Simon, a long-time resident of Mathare and our Map Mathare Coordinator, put it on the Mathare Valley blog: “One does not need to be a scientist to know what would happen in case of disease outbreak. The improvement of proper water distribution and repairing the broken water pipes coupled with constructing good drainage system is the key to fighting common illness in the slums.”

What I can add to all of this is that in order to improve or at least start improving living conditions, you need to first know and understand the situation on the ground. By mapping open drainage areas, our mappers are providing the first detailed geographical information about how open drainage is distributed throughout Kibera and Mathare, thus providing necessary information to anyone hoping to solve the problem.

This I believe answers the question of why and brings me to the next question: How?

Obviously open drainage creates “appalling living conditions,” but maybe not so obviously, it creates appalling mapping conditions too! Open drainage winds and curves between houses, often sinks below them, intersects, flows, stands, overflows, merges with the content of broken sewage lines (sewage lines burst and sewage comes above ground, mixing with the content of open drainage), and creates pools of standing water. Open drainage is the main collector of garbage: garbage in open drainage areas often clogs drainage systems, thus creating floods during rains. All of this mesh slowly flows downwards, usually towards rivers that pick it up and carry it further downstream, polluting the environment sometimes hundreds of kilometers away.

In order to understand the scale of the problem in Mathare and Kibera we went on an investigative – or, if I put it in army terms, reconnaissance – mission with our teams to see the problem first hand. Our participants surveyed the problem, and their input helped us to better understand what we’re up against. We walked through the slum evaluating different drainage lines and problems we faced in mapping them, Sebastien (our new volunteer) and I then facilitated the mappers to decide on which points of interest we should collect and in what order.

Investigating the problem

Findings from the field regarding open drainage include:

  • Open drainage has many sources and it forms for many reasons (resulting from topography and from human actions)
  • It comes in many forms regarding the content and structure (garbage, water, sewage, earth trench, concrete trench, etc.)
  • It has main channels with many tributaries

We came to realize that drainage systems in slums (Kibera, Mathare) basically work as micro river systems! This made us understand that it has to have an outlet, and both Kibera and Mathare have outlets in the form of rivers that run through them.

All of this helped us made our action plan:

  • All the drainage flows towards the rivers, so we started collecting data along the rivers.
  • The next step is to collect data for the main channels, which lie along the main paths.
  • After this, we focused on the smaller paths in the slum, collecting points of interest along the way. This includes the start and end points for “following” a drainage line, intersections of different lines, man-holes (along sewage lines), and broken sewage lines. At intersections, we’re collecting the directions of different intersecting lines
  • Throughout this process, the use of building extraction (when possible) helps us sketch the drainage lines

After the extensive data collection we’ll use the satellite imagery and building extraction to help us determine the exact positions of drainage lines.

Mapping Open Drainage

So, what’s next?

Just knowing and understanding the situation will not make it better. This means that our process cannot end with mapping, but will take the map and the information we collect a step further to actually make the information useful and create an impact. The next step is bringing together community members, stakeholders, NGOs, local administration and government representatives and expose the problem with a method I like to call: “A punch in the face” – where we present the problem, with maps and other media, in all its vastness, and hopefully get some heads thinking and acting upon the information which is presented. The map lets stakeholders present problems to responsible actors in a comprehensive and difficult to ignore manner, making the issues more concrete than just words by providing detailed geographical representations of their scope and characteristics.

In order for this last step to be successful, local ownership, insights, and understandings of both the issues at hand and how mapping and presenting information can help bring change, is crucial. Creating this local ownership amongst key stakeholders – namely the local Map Mathare and Map Kibera teams – has to start from the very beginning of the process. We are working hard to create this local ownership from the beginning in Mathare and to bring a greater sense of ownership to the Kibera teams.

Map Kibera and Map Mathare are currently involved in vast mapping operations regarding Water and Sanitation in both Mathare and Kibera, two of the biggest slums in Nairobi. These projects are big as the issues they are trying to address and will present test whether exposing vast quantities of information about a particular issue truly has the ability to influence change. As I often say: Collecting data, as complicated and hard as it may be, is the easiest part here.

[More of the same on Mapping: No Big Deal]

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§ 3 Responses to “Why Map Open Drainage? And How?”

  • Will says:

    Do you have any other representations of the data besides the map on this page? I’m interested in the specifics of how you collected and will use this data.

    • primoz says:

      Hi Will,

      Yes we have quite an extensive array of data.

      We have shapefiles of open drainage lines in 4 villages of Mathare, we also have shapefiles of open defecation areas, toilets and water points containing very detailed information for the whole of Mathare.

      I Kibera we have shapefiles of toilets, water points, dumping sites, etc. On top of this we have maps which were drawn on top of our maps by the residents of Kibera. By doing so they pointed out the biggest problems and also solutions regarding the issue (I’m just working on them now). In Kibera we’re currently re-doing Water and Sanitation mapping there.

      We also have couple of hours worth of video footage, hundreds of pictures and numerous residents accounts.

      At the moment we’re in the process of merging all this data and creating something useful for all interested parties.

      You’ll be able to see our progress on this page and if you need some specific information you can also contact us.


  • Katie Boyle says:

    Congrats on your great work. I also work in public health and GIS, based in the US but doing both local and international health projects. I am currently putting together videos of slums and came across your blog. Please let me know if you need any GIS assistance on your project.
    Katie Boyle

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