Cascading failures of Critical Infrastructure during floods in Manzese Ward — Dar es Salaam
Turning a Mancala board game into a flood impact assessment tool
Authors: Hessel Winsemius, Shristi Vaidya, Nyambiri Kimacha, Andres Diaz Loaiza
A vlog post about CIrcle-Bao can be found on https://www.deltares.nl/en/news/failures-critical-infrastructure-floods-training-red-cross-volunteers-dar-es-salaam/
Critical infrastructure such as roads, power stations, transformers, water points and health centres, plays an important role in the functioning of wards in Dar es Salaam. If critical infrastructure fails, the livelihoods and particular vulnerable groups in society cannot function properly. And the problem is: they do fail! There are many flood prone wards in Dar and these floods disrupt or destroy this infrastructure. The complexity is that as one infrastructure fails, others may as well in cascade. As part of a GFDRR/DFID funded “Challenge Fund” project, Deltares, VU University Amsterdam, Tanzania Red Cross Society and Red Cross Red Crescent Climate Centre, developed a physical tool to allow local stakeholders to understand their own vulnerabilities related to critical infrastructure and cascades of failure. Let’s start this blog with a short fictive story.
“My name is Grace. I lived in a small house in Manzese ward — Dar es Salaam close to the Manzese BRT station. It was just me and my boy Mwansa. It had always been like that it seemed. His father never wanted to acknowledge him and left when he heard of my pregnancy, so it was just the two of us managing.
It was a night in December. I heard a distant rumble of a thunder storm. Slowly but steadily the noise of the thunder was getting closer. Suddenly heaven opened up. My boy Mwansa didn’t like heavy rainfall. He woke up and cried. The noise of the heavy downpour on our tin roof was so loud that I almost couldn’t hear him. Luckily I just repaired the roof so I was dry and warm. I comforted Mwansa and he fell back a sleep. After a few hours, the rains passed, as the last drop fell, suddenly, a few blocks away, I heard a loud bang. People were screaming.
The next day, everything looked normal again. The sky was crisp clear. I took Mwansa to fetch water at the water point a few houses away, before bringing him to school. Upon arrival, the operator looked at me and said: “Don’t you know that there has been a blow out? Power’s gonna be off for a long time so the pump of the water point doesn’t work anymore!” That must’ve been it! The big bang must have come from the blow out!
Not a problem. The nearest water tap was about half a kilometer away across the stream. Mwansa sang loudly and ran ahead. He forgot all about the rainfall of the night before. I walked carrying my container on my head. But then Mwansa came running back. “Mama, mama, there’s water everywhere. The smell is terrible!” As I passed the corner of the hardware store, I looked over a dramatic scene. The road, descending to the bridge was flooded. In a distance I could see the bridge. It looked like a huge tree floated into the small bridge’s pier. Its branches extended all the way over the road and a large pile of solid waste had accumulated in front of it. It was impassable.
What to do! I needed water! I walked to Mwansa’s school but there I was told that the school was flooded and also there no water was available. The flood water had contaminated the water source and drinking it would mean a certainty of diarrhea. I couldn’t take Mwansa to my work on the market, my boss doesn’t like children. The last time I took him he told me he would beat him out of the market place if I would ever bring him again…”
Cascading flood impacts
The story of Grace may be slightly dramatized, but it is still quite reasonable to assume that this may happen. The story demonstrates that not all flood impacts are direct but that they instead may be caused by failure of so-called “Critical Infrastructure”. These are goods, services and infrastructure that people need to function properly in a neighbourhood. Grace’s living situation is seriously disrupted, not because her house and property is under water, but because water points in her neighbourhood have failed, her son cannot go to school, and because of that, her job’s on the line, because she is not allowed to bring her boy with her.
Who is vulnerable?
Grace’s story shows that particular groups in society may be disproportionally vulnerable to flood impacts. Women and children are particularly vulnerable, because they strongly rely on infrastructure that may fail during flooding. In Dar es Salaam, women in general have the largest responsibility to keep the house running, and therefore, carrying water and taking care of children lies in their hands. The disruption of water means that women may have to walk much further to get their daily required water supply and the disruption of school means that they also have to attend to children who by extent are left without education.
CIrcle-Bao: inventorizing cascading impacts through failing critical infrastructure on vulnerable groups
The basis of Grace’s story does not come out of thin air. It was collected by 5 Tanzania Red Cross Volunteers (TRCS), all inhabitants of Manzese ward.
They were trained by a team from Deltares, VU University Amsterdam and Tanzania Red Cross Society head quarters, to conduct a structured stakeholder dialogue about flood impacts on critical infrastructure, and how failures of critical infrastructure may be caused by cascades. Remember that due to flooding surrounding Grace’s house, there was a transformer blow-out, electricity failed, and by extent, also the water point near Grace’s house failed, causing her to have to look for water elsewhere. The dialogue is structured by using a newly designed physical tool called “Circle-Bao”, based on our original digital tool CIrcle. The tool consists of a round board, based on the popular Mancala game “Bao”, a set of coloured pawns, each colour representing a particular critical infrastructure, and coloured cards, representing impacts that one infrastructure can have on the next. The nice thing about CIrcle-Bao is that it can be locally produced. We had a local craftsman make two boards for use within Tanzania. If you wish to reproduce the board and workshop, please have a look at our guidelines.
CIrcle-Bao can be attended by a total of 10 stakeholders, each representing a single critical infrastructure (CI). In Manzese, the identified most important CIs included Roads, Electricity, Market, Solid waste and drainage, Places of worship, Water points, Police, and the Human settlement. The CIs are represented by a colour on the Bao-board, as well as that same colour in the form of pawns. Each CI starts with the same amount of pawns in his/her color. The discussion goes as follows.
First, the “facilitator” asks each CI representative when that particular CI experiences some direct impact of flooding and when it experiences complete failure. This can be indicated by means of the water depth. What impacts are experienced specifically and which groups in society are affected is the most important focus of the discussion. A “recorder” summarises the discussion on pre-printed cards. The facilitator does a complete round so that each CI representative can speak and its impacts can be discussed. The summary card is placed on a pawn of the same colour as the box that represents that CI and placed in the inner Direct Impact ring of the Circle-Bao board.
Then a second round is done. But now, per CI, the facilitator asks which CI is affected in cascade by failure of the CI under investigation. Any CI raising a hand is investigated for the severity of the impacts experienced and the discussion on impacts is summarized on a pre-printed card by the “recorder”. The recorder selects a green, yellow or red card, according to agreed upon levels of severity associated with these colors (green, mild impact; red, severe impact). The card is placed on a pawn of the colour of the CI causing the havoc, but placed in the box of CI that experiences the impact in the outer Cascading Impact ring of the Circle-Bao board. An important role here lies with the “observer”. The observer is the one in the team carefully assessing how the discussion goes. If the discussion is too much off topic or the facilitator is too much engaged in the discussion rather than facilitating it, the observer can intervene and try to get the discussion on track.
Meaning of the results
After the two rounds (direct, and cascading impacts rounds) are done. The board is full of data, represented by colors. For any given CI, the data can be interpreted and summarised as follows:
- The amount of pawns representing that CI that is left with the CI representative after the discussion. The lower this amount, the larger the number of cascading impacts this CI causes on other CIs.
- The amount of pawns of other colors, put into the CI’s Cascading Impact Ring. The higher this amount, the more cascading impacts this CI receives from other CIs.
- The color codes of the cards, describing the cascading impacts of other CIs. If these are concentrated in the red domain, the CI receives severe cascading impacts. If these are more in the green, the impacts are relatively mild.
After the session it is therefore straightforward to assess the CIs that, upon failure, cause the most misery, and the ones most susceptible to misery caused by others. The Red Cross volunteers and participating stakeholders discovered in this way that the most severe impacted CIs through cascading were roads and schools, while the CIs causing the most misery when failing were water points and electricity. Whilst investigating their direct impacts of failure, we found that women and children are more affected when these fail. This is embodied in our fictitious story of Grace and her little boy Mwansa.
So what now?
The CIrcle-Bao session showed that cascading impacts exist in Manzese, and that these can be substantiated through discussions and stories. But more importantly, the outcomes represent first concrete and stakeholder supported evidence which infrastructure cause the largest vulnerabilities and to which groups in society. Ideally, these infrastructures should be designed or retrofitted to become more robust to floods. New infrastructure should be better spatially planned or built less vulnerable. We hope that this evidence is brought to the right decision levels in due time. Finally, we hope that CIrcle-Bao can be brought to the next level and embedded as a physical tool to improve the understanding of flood risks with and for stakeholders affected by it.
Acknowledgements: we thank all Red Cross volunteers for attending our training. We are very grateful to Mohamed Issa Mohamed, Jackline Msabaha, Magdalena Albert Leo, Anthony Cosmas Nguzo and Jonas Maheto for conducting the CIrcle-Bao workshop after their training. Finally, particular thanks go to Jonas Maheto, Bernard Mashauri and Prosper Boaz Ngetelwa for their amazing translation work during the training as well as the CIrcle-Bao session.
