Reinventing cities for the extreme rains and droughts to come06/18/2020
By implementing simulation models and continuous monitoring, extreme weather situations can be foreseen and thus reduce their effects. Credit: Project BINGO.
FRANCESCO RODELLA | Tungsteno
2019 was the hottest year in Europe since records began. If the forecasts are correct, the extreme periods of hot weather in recent years will become more frequent and will be accompanied by related phenomena such as heavy rains and droughts, whose impact on cities can be devastating. This is especially true in the Mediterranean basin, which is warming 20% faster than the global average. Cities need to adapt to resist the effects of these adverse weather situations. This is the objective of BINGO, a European project that proposes innovative solutions in water management to meet this challenge.
Badalona, in the Barcelona metropolitan area, is one of the urban areas most sensitive to the impact of these phenomena. The city —which has some 220,000 inhabitants— faces two main problems from the outset. One is that it can suffer from flash flooding when it rains heavily because water flows rapidly from the upper part of the city to the lower area, which in extreme cases can endanger people or property. Another challenge is that during the heaviest rainfall the sewage system overflows, releasing wastewater into the sea and polluting its beaches. Floods recur in cycles of approximately three, four or five years; however, the sewage system discharges can occur up to four or five times in the same year, according to Beniamino Russo, professor at the Polytechnic University of Catalonia and the University of Zaragoza, as well as project manager at the company Aquatec.
Big data and simulation models to alert citizens
To reduce this impact, Russo and his team, with the collaboration of municipal administrators and technicians, have proposed various adaptation measures. Those of a structural nature include the construction of new tanks and sewage lines. The installation of sustainable drainage systems, such as the use of green roofs, the creation of infiltration ditches or the installation of permeable pavements, is also planned. In addition, non-structural measures have been proposed, such as the implementation of a comprehensive early warning system for the public. This initiative combines the monitoring of service and infrastructure networks with more innovative techniques that allow simulation models to be used to forecast these extreme events, including heat waves and air pollution. In this way, operating procedures and protocols for warning residents and visitors can be established.
The installation of sustainable drainage systems as well as an early warning system for the public will allow cities to better resist the effects of extreme weather events. Credit: AVAMET.
The team led by Russo has studied the potential evolution of rainfall and its impact over the next decade, and until the end of the century, through climate projections provided by the Free University of Berlin (Freie Universität Berlin). From there they have concluded that extreme rainfall events could increase by up to 15% in Badalona, which would mean an increase of up to 30% in damage due to flooding. "The hydraulic risk associated with potential economic or human life losses is not proportional to rainfall," explains Russo. In fact, the project has also studied the economic cost of these scenarios if action is not taken to limit their impact: urban flooding would entail an additional annual cost of 1.9 million euros for the region, while in the case of pollution as a result of the spills, it could reach up to 1.4 million euros per year.
All these initiatives are part of the European project BINGO to improve the resilience and adaptation of cities to extreme weather conditions. But the impact of climate change is not exclusive to the regions of the Mediterranean basin. Other areas of Europe will also suffer the consequences of this anthropogenic phenomenon, as shown by the 20 public and private organisations participating in this project, developed between 2015 and 2019 with funding from the EU’s Horizon 2020 programme. In addition to Badalona, five more cases have been studied within the framework of BINGO, each with different characteristics, both in terms of orography and geographical location, in Portugal, Norway, Germany, the Netherlands and Cyprus.
The design of structures for water containment helps prevent flooding in the event of torrential rains, frequent for example in the surroundings of the Wupper River (Germany). Credit: Georg Sander.
Changes in planning and improvements in water management
Thus, it has thus been possible to analyse the consequences of the more intense droughts and floods expected from climate change in the lower Tagus basin, and what their impact will be on farmers in this area of Portugal. It has also been observed how the scarcity of rainfall will affect the water supply in the rural communities of the Troodos mountain system in Cyprus. The effect of less rainfall, or more flash flooding, around the Wupper River, a region of Germany that also has a large number of dams, has also been analysed. The other two cases under observation are the groundwater reservoir in the large Dutch forested area of Veluwe, and the urban drainage system in Bergen, Norway, one of Europe's wettest cities.
Making these cities and regions better able to adapt to and resist these effects is possible according to those responsible for this programme, who have put forward various solutions to achieve this. These measures require new planning and management improvements, such as the use of wastewater for irrigation in the Troodos mountain area. Other measures include the provision of information and forecasts, for example, to all users of the water resources of the Tagus, or the building of structures for water management, such as a retention basin to prevent flooding in the analysed area of the Wupper River.
"Cooperation and coordination between local actors with management responsibility and researchers is the key to providing adaptation measures that are truly implementable," notes Russo. In his opinion, although it is difficult to say whether or not we will be in time to avoid serious impacts in the area of water management due to climate change, we do have the arguments to justify our actions in the fight against it. In fact, these pilot projects, developed under the umbrella of the BINGO project, will allow these innovative initiatives to be designed for other cities in order to make them more resilient and, therefore, more liveable and safer for their inhabitants.
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