I think some water's coming down

Cinematic reality

I think some water’s coming down, eh

That is what I wrote on 29 April 2024, a year ago, in a WhatsApp group of professors and students from the Institute of Hydraulic Research (IPH). The group had been created in September 2023, in the context of the heavy floods that inundated cities in the Taquari River Valley.

This group became active again in November 2023, when other rains caused new floods, this time hitting Porto Alegre and the metropolitan region. On that occasion, I helped create material for the press, which was released to illustrate what would happen if a flood like the one in 1941 were to occur again, without the dyke protection system. It was featured in G1 and Correio do Povo.

Without a protection system, Guaíba would flood the airport, Public Market, and stadiums, study says | Rio Grande do Sul | G1

Interactive map compares the largest floods in Porto Alegre’s history

Nothing is created, everything is copied. The idea for the map had already been the subject of the Undergraduate Thesis of my dear friend and colleague, Eng. José Augusto Müller Neto. But in 2023, the map needed to be more interactive and customised for public dissemination.

Fast forward to late April 2024, and reality was about to become far more cinematic.

After the message I sent to the group, we experienced the advent of the greatest hydro-climatic disaster in Brazilian history. From that moment on, it felt as though I had entered a psychedelic horror trip that would never end. When I finally managed to stop working, near the end of May, I had the impression that years had passed.

Information router

The result of so much work was the formation of a network of researchers who, by some miracle, managed to coordinate themselves to communicate vital information to society.

On the 1st of May, for instance, Eng. Matheus Sampaio, along with Professors Rodrigo Paiva and Fernando Fan, began a series of level forecasts for Lake Guaíba. These forecasts were made on a personal computer, based on simulations of hydrological and hydrodynamic models using publicly available data. The results were published on the Institute’s page in the form of bulletins.

Based on the forecast from the 2nd of May, Environmental Eng. Sofia Royer kindly “summoned” me to produce risk maps for Porto Alegre, similar to those from November 2023. That is when the maddening activities began. Still on the night of the 2nd of May, I posted a risk map on the GESPLA blog and sent the following message to practically all my contacts:

Folks, I hope you are all well. We have a critical scenario for Porto Alegre in the coming hours and days. It is possible that the imminent flood will exceed any historical record, including 1941. In one of the scenarios recently simulated at IPH, it is possible that the flood protection system (walls and dykes) will not hold. In that case, water from the Jacuí River and Lake Guaíba would flood a large part of Porto Alegre, just like in 1941. It wouldn’t just be internal water logging anymore, but the entry of external water. Check the interactive map in the link below for the areas that could possibly be affected in this scenario (for example, looking at the 1941 flood). This scenario is extreme, but it must be considered a possibility. The goal isn’t to panic, but to take this scenario seriously. The link also provides other resources and information, possibly updated. Best, Iporã Possantti, Environmental Engineer, PhD candidate at IPH/UFRGS (on 2/5/2024). https://www.ufrgs.br/warp/2024/05/02/mapas-das-cheias-historicas-em-porto-alegre/

On Friday morning, the 3rd of May, this text served as the basis for an institutional message from IPH, published in GZH.

Hydrologists urge Porto Alegre to prepare for evacuation; see what the flooding would look like | GZH

While the Institute’s professors were writing these official messages, I had to explain the map to a colleague from the Civil House, who was gathering information directly from the source to report to the President’s Office. Scenes like these began to repeat. My life, like that of many other scientists, became something of an information router for the next 30 days.

The synthesis of it all

Thanks to the technical competence of many colleagues, within 10 days we managed to organise the materials into a website that provided a synthesis of everything, which became known as the “map repository”.

The database we created (at insane speed) was very useful for other independent researchers calculating the scale of the disaster. Researchers from IPEA, for example, at the request of the Ministry of Social Development, used the data to estimate the volume of resources for aid to the displaced.

Later in 2024, we managed to resume activities more appropriate for researchers, such as writing scientific articles about what happened. I had the privilege of working on the writing and visualisations of an article describing the disaster in hydrological terms, recently published in the Brazilian Journal of Water Resources.

Another interesting article, which I am coordinating, focuses on a broader account of our activities. It hasn’t been published yet, but a draft of it, in Portuguese, can be accessed at the following link:

An account of the experience of risk communication by volunteer researchers during the 2024 climate disaster in Rio Grande do Sul, Brazil (data and preprint)

When will we have peace?

I confess that the 2024 flood did not leave me impressed by the high water levels. But I admit to being surprised by the low level of technical capacity of the public administrations in Rio Grande do Sul.

One example I will never tire of repeating was the decision by Porto Alegre City Hall to create a shelter at Pepsi On Stage, ignoring any technical guidance regarding the hydrological risk of that area. They hurriedly changed locations just before the site was completely submerged. Conclusion: there was no plan.

If a new flood occurred today, who would officially inform the main cities of the State of river levels with reasonable notice? Where can an ordinary citizen open an official interactive map and find out the degree of hydrological risk for any given place? Or find out, officially, the last maintenance date of a floodgate or a pumping station?

All of us technicians know that data and methods already exist to have a very robust starting point in this regard. There are already exemplary initiatives, such as SACE from the geological service, or the 2018 study by Metroplan.

But in general terms (and I may be being unfair), it seems that in a repeat scenario, we will depend on the voluntary bulletins of my colleagues and simulations done on personal computers. Then someone will have to make risk maps and share them on the internet.

Again.

When will we have peace?