Flooded or floating cities? An investigation on flood management systems in Latin American, Caribbean and European cities

• Stefania Vallejo (Ecuador) and Claudia Wiese (Germany)
• 26. August 2020

While flooding is one of the most frequent natural disasters in the world, not all countries have the same financial and technical means to deal with its consequences. The following article looks at the differences in flood management systems in Latin American, Caribbean and European cities with the aim of pointing out problems and finding cost-effective, innovative solutions to prevent and deal with the consequences of flooding.

Introduction

Regularly, news about the El Niño phenomenon ravaging Latin America and the Caribbean (LAC) with severe flooding are broadcast all over the world. In 2015 alone, 150 000 people had to flee their homes swept away by raging torrents in Paraguay, Northern Argentina, Southern Brazil and Uruguay.[1] According to the UN report “The Human Cost of Weather Related Disasters,” 2.3 billion people were affected by flooding events between 1995 and 2015, accounting for around 56% of those affected by weather-related disasters.[2] However, the world is unequally affected: for example, while LAC countries struggle to deal with the human as well as financial consequences and barely invest into prevention mechanisms, European countries have been developing well-functioning mitigation strategies. Additionally, most floods happen in densely populated urban areas which is particularly challenging for LAC cities, where rapid and chaotic urbanisation has led to the emergence of illegal settlements highly vulnerable to natural disasters. Climate change, as well as the anthropogenic destruction of natural defence systems such as forests in and around cities, will certainly contribute to the rise of flooding in the next decade. So, why did LAC countries do so little to mitigate flooding risks and what should they do in the future? Should they follow the European model, or is that too costly?

The following article will shed light on how LAC and European cities cope with flooding due to heavy rain or water level rise. Although these two regions are quite different topographically and socio-economically, it is worth looking into best practices and point out areas where the European Union (EU) and LAC countries can cooperate with each other for more efficient flood protection mechanisms. For instance, the EU has developed a legal framework for the implementation of structural responses (notably, dikes or tidal regulation systems) and non-structural ones (e.g., flood maps) which might be of interest for LAC countries, of which most do not even have an early warning system.

1. Integrated approach for flooding management in European cities

 On the European continent, the number of disasters attributed to flooding has risen since 1998. According to a study conducted by the ENHANCE Project, the occurrence of extreme and catastrophic floods will increase to a rate of 1 every 10 years by 2050 compared to the current rate of 1 every 16 years.[3] The study also indicates that the average annual economic losses caused by flooding in Europe will total € 23.5 billion – which represents over five times the amount for the 2000 to 2012 period. [4]

Within the EU, Flood Risk Management (FRM), which aims to reduce the likelihood and impacts of floods, is based on both structural and non-structural responses that follow two directives: the EU Water Framework Directive 2000/60/EC and the EU Flood Directive 2007/60/EC. The latter focuses on prevention, protection, preparedness, emergency response, recovery and lessons learnt.[5]

Regarding structural response systems, the German city of Hamburg has built cascading flood embankments to minimise the effects of possible floods of the Elbe River. In the HafenCity area, dikes and buildings built upon plinths are part of the structural response of the harbour city to mitigate the effects of flooding and all new buildings stand on artificial bases that are built at 8 meters above sea level. Furthermore, new roads and bridges have to be built over 7.5 meters above sea level. [6] In its neighbouring country, the Dutch city of Rotterdam implemented the Delta Works Program that involved the building of dike-rings and damming of bays with floodgates. The Maeslant Barrier is an example of a movable gate whose doors close when the sea level rises above 9.1 centimetres.[7]

Among the non-structural measures implemented in Europe, flood emergency planning is the cornerstone of the FRM. These plans are mandatory in flood risk areas containing comprehensive contingency plans that cover crisis management before, during and after flooding events. In the Netherlands, flood and evacuation maps along the Rhine basin show mandatory evacuation routes. Furthermore, Land Planning – which consists of a set of preventive measures that aim to avoid the construction of buildings in flood basin areas – discourages any construction that forms an obstacle to the natural flow of water. In the United Kingdom, authorities and citizens can access an interactive online Flood Map, a portal that provides up to-date information on flooding events. The goal of this initiative is to increase awareness among people regarding flood risk and to encourage them to take preventative actions. The website also serves as a portal for planning permissions in flood-prone areas for the inhabitants of England and Wales.[8]

Early warning and forecast systems are also key measures in the flood prevention repertoire of European cities. The Flood Alert System (FAS)[9] and the European Flood Forecasting System, based on the LISFLOOD[10] rainfall simulating model, help forecast flooding up to 10 days in advance. In Augustenbord in Malmö, Sweden, authorities implemented flood risk management and waste management procedures with sustainable urban drainage systems (SUDS).  Measures included retention ponds and green roofs – which act as a natural rainwater management device that uses vegetation and soil to reduce the runoff response.[11]

2. Flooding in Latin American and Caribbean cities call for better risk management strategies

Contrary to European countries, most LAC countries do not have a well-designed regulatory framework to deal with natural disasters. According to the Inter-American Development Bank (IDB), LAC countries face the highest median costs per disaster with a cost of about 0.18% of GDP per event.[12] Additionally, total disaster costs in the last three decades (1980-2010) surpassed those of the previous eight decades between 1900 and 1980.[13] The latter trend is not only a consequence of climate change but also of population growth and the rapid and uncontrolled process of urbanisation. Between 1970 and 2015, the urban LAC population rose from 50% to 80%, leading to overcrowded, unstructured cities prone to the development of slums in dangerous areas (e.g. in flood prone areas) and crucially lacking risk management strategies as well as the necessary infrastructure – such as pluvial drainage systems – to cope with extreme weather phenomena. As a consequence, 86% of registered disaster events in LAC between 1980 and 2009 happened in urban and peri-urban areas entailing large-scale human displacements and casualties.[14]

However, despite the increased flooding risk, many LAC cities fail to develop efficient disaster management systems because of their high upfront costs. For instance, the above-mentioned Dutch Maeslant Barrier cost about €635 million including dike reinforcements.[15] Yet, some easily implementable and cost-effective strategies exist; following heavy rainfall in 2002, which led to the death of 74 people and 120 injured, the Bolivian city of La Paz developed an early warning system and a risk map for better land use planning. In 2011, heavy rainfall led to a mega-landslide, which affected 26% of the city; however, thanks to the efficient early warning system, everyone could be evacuated in a timely manner and no human lives were lost.[16] Although the consequences of landslides are different from those of flooding, the latter example clearly illustrates the power of an early warning system in the prevention of human fatalities. Another interesting approach lies in ‘constructing with nature.’ The idea is that infrastructure projects should respect the environment within and around cities and to use these natural resources as barriers against flooding. For instance, mangroves can reduce wave heights as much as 66%, providing a cheap and efficient natural barrier against flooding in coastal cities.[17] Unfortunately, mangrove forest destruction has been highest on the Caribbean coast where cities would benefit most from this natural protection system.

In addition to these easy implementable measures, dams, large scale upgrading of housing substance and more efficient pluvial drainage systems are also desirable. For instance, drainage systems are often blocked by uncollected waste. In La Paz, about 30 tonnes of rubbish per day end up in the drainage system and therefore it cannot fully operate when needed.[18] Hence, recycling would be one way to face this problem. To finance these structural response systems, LAC cities have several options. For example, since the severe flooding incidents in Colombia between 2010-2011, generating a loss of USD 11.2 billion, the country has worked closely with the Dutch Government to develop an early flood management system and sustainable cities schemes with the expansion of parks as natural flood protection areas.[19] Besides, to get a better grasp of informal settlements in disaster-prone areas, the city of Bogota implemented a cadastre system to register housing constructions. The system not only enabled the identification of urban areas but also the collection of property taxes, which increased local government revenues 2.5 times and thus its financial capacity to cope with natural risks.[20]

Conclusion

In the past, LAC countries have not invested sufficiently in risk management strategies because of the lack of a legal framework and high upfront cost of structural mitigation responses. To tackle these problems, a three-pronged approach for LAC countries in managing this risk could greatly improve the current situation. The first component of the approach consists of international collaboration – the example of Dutch-Colombian collaboration illustrates a great opportunity for LAC countries to effectively anticipate and manage future flood risk – leveraging decades of investigation, investment and lessons learnt in flood-prone Western Europe. The second is to focus initially on non-structural solutions that put countrywide preventative policies and processes in place. For instance, the implementation of a flood management plan for each and every river basin should be developed. Non-structural solutions require relatively low investment (compared to structural measures) and can be effectively adapted from European best practices.  Finally, the third approach is to selectively invest in structural solutions, which focus on structural investment in the highest risk cities with an emphasis on natural solutions into a safe sustainable urban future.

References

[1]BBC Mundo (2015); Evacúan a 150.000 personas en Paraguay, Uruguay, Argentina y Brasil por inundaciones; URL: https://www.bbc.com/mundo/noticias/2015/12/151226_america_latina_argentina_paraguay_uruguay_brasil_inundacion_desplazados_ppb (Last Access: 13/07/2018).

[2] UNISDR; The Human Cost of Weather Related Disasters 1995-2015; URL: https://www.unisdr.org/2015/docs/climatechange/COP21_WeatherDisastersReport_2015_FINAL.pdf  (Last Access: 13/07/2018)

[3] Enhancing Risk Management Partnerships for Catastrophic Natural Disasters in Europe

[4] European Commission (2014), Science for Environment Policy: European costs could increase almost five-fold by 2050. http://ec.europa.eu/environment/integration/research/newsalert/pdf/372na7_en.pdf

[5]European Commission (2014), Links between the Floods Directive (FD 2007/60/EC) and the Water Framework Directive (WFD 2000/60/EC). https://circabc.europa.eu/sd/a/124bcea7-2b7f-47a5-95c7-56e122652899/inks%20between%20the%20Floods%20Directive%20and%20Water%20Framework%20Directive%20-%20Resource%20Document

[6] Voorendt, Mark (2012), Flood Defences: Hamburg, https://www.flooddefences.org/hamburg.html

HafenCity Hamburg GmbH. (2018), Flood-secure bases instead of dikes: safe from high water in HafenCityhttps://www.hafencity.com/en/concepts/flood-secure-bases-instead-of-dikes-safe-from-high-water-in-hafencity.html

[7] Grossman, Daniel. (2015), A Tale of Two Northern European Cities: Meeting the Challenges of Sea Level Rise.https://e360.yale.edu/features/a_tale_of_two_northern_european_cities_meeting_the_challenges_of_sea_level_rise

[8] Hegger D. et al. (2016), A view on more resilient flood risk governance: key conclusions of the STAR-FLOOD project.http://www.starflood.eu/documents/2016/03/d6-4-final-report-webversion.pdf.

[9] European Commission (2017), European Flood Awareness System.  https://www.efas.eu/

[10] LISFLOOD model is a hydrological rainfall-runoff model that is capable of simulating the hydrological processes and thus provide predictions on flooding.  Burek, P et al. (2013), LISFLOOD: Distributed Water Balance and Flood Simulation Model. https://publications.europa.eu/es/publication-detail/-/publication/e3b3c713-c832-4614-8527-f3ab720192f8

[11]Hegger D. et al. (2016), A view on more resilient flood risk governance: key conclusions of the STAR-FLOOD project.  http://www.starflood.eu/documents/2016/03/d6-4-final-report-webversion.pdf

[12] Inter-American Development Bank (2013), Infraestructura Sostenible para la Competitividad y el Crecimiento Inclusivo; Estrategia de infraestructura del BID

[13] ILLESCAS Coral F., BUSS Stefan (2016); Ocurrencia y Gestión de inundaciones en América Latina y el Caribe – Factores claves y experiencia adquirida; BID.

[14] MANSILLA Elisabeth (2010); Riesgo Urbano y Politicas Publicas en America Latina: La Irregularidad y el Acceso al Suelo; ISDR, UNDP, Corporación OSSO.

[15]Website of Deltawerken (construction of the Measlant Barrier) http://www.deltawerken.com/Indispensable-/464.html

[16] FILHO Walter L. et al. (2018), A Comparative Analysis of Climate-Risk and Extreme Event-Related Impacts on Well-Being and Health: Policy Implications; Int. J. Environ. Res. Public Health, 15(2), 331.

[17] MCIVOR Anna, MÖLLER Iris, SPENCER Tom, SPALDING Mark (2012); Reduction of Wind and Swell Waves by Mangroves; Natural Coastal Protection Series ISSN 2050.

[18]ILLESCAS Coral F., BUSS Stefan (2016); Ocurrencia y Gestión de inundaciones en América Latina y el Caribe – Factores claves y experiencia adquirida; BID.

[19]ISHIZAWA Oscar A. (2018); The Disaster Risk Management Challenge for Small Cities; World Bank Blog – Latin America & Caribbean.

[20] TROHANIS Zoe E. (2018); What is the first step for organizing Peru’s cities?; World Bank Blog – Latin America & Caribbean.