Prague: What are snails and fountains for? Fight the heat with trees
In Prague, as in cities throughout Central Europe, as a result of climate change, temperatures are slowly ending and extreme weather events are increasing. “More frequent occurrences of tropical or heat waves are very likely on likely days,” Peter Konvalinka, Chairman of the Technology Agency of the Czech Republic (TA ČR). That is why the project of domestic researchers was created, which will be provided financially by TA CR in the amount of 2.1 million crowns. The Academy of Sciences of the Czech Republic (CzechGlobe) and Palacký University in Olomouc (UPOL) also collaborated on it.
Trees and lawns, saviors of the city?
For example, trees in an open area in the city center during the day feel a cooling effect on the air temperature up to about 8 and a half to 11 degrees Celsius in the shade compared to the temperature in the sunlit area. In the streets, trees have a smaller effect, on average approx 4 degrees Celsius, and at night, on the other hand, it slightly suits the feeling temperature. “Trees generally reduce air temperatures throughout the day, depending on the time the reduction varies between 0.4–2.1 °C,” says Michal Lehnert from UPOL.
Although an unirrigated lawn has a surface temperature equal to hot soil, an irrigated one can up to 20 degrees lower. However, it is essential that there is a bond to the lower layers of the soil, otherwise it will heat up like a concrete pavement. This is an example of grassed tracks. Other results show elements of blue infrastructure and water work.
The fountains in the squares have a minimal effect on reducing the air temperature. Water jets or mist gates reduce the air temperature by approximately 1.2 °C. In addition, the cooling effect only binds to the non-surrounding water element. Sprinkling the streets does require a surface temperature, but only for 20 minutes and only by 1.3 to 3.1 degrees Celsius.
However, it cannot be said that any measures are unnecessary. “On the other hand, they have a different function – sprinkling the side reduces dust in the streets, the fog gate is “loved” by children, and drinking cups are important for fluid supply during a heat wave,” help Jan Geletič. Green facades and roofs are also not very effective in reducing the air temperature, but that’s about it surface temperature or retain rainwater. The effectiveness of a measure is one side of the coin, the utility is the other.
“For example, the historic fountains in Olomouc’s squares have zero functionality, but only have historical and aesthetic value,” says Jan Geletič. The same could be applied to Prague. For modern measures, functionality should prevail. As far as water is concerned, drinking fountains waste minimal water, but rainwater is not used much. According to Jan Geletič, cities should focus on this.
The situation in Prague
The climate project was developed in cooperation with representatives of the cities of Brno, Olomouc, Ostrava and Pilsen. He provided the researchers with the necessary background, data and feedback. “Practically, one could say that similar conclusions apply to Prague as to Olomouc (both cities have monuments registered on the UNESCO list),” says Jan Geletič from the Academy of Sciences.
Cities praiseworthy, the state insufficient?
According to conservationist Petr Stýbl, lower administrative units approach nature better than regions and the state. “Municipalities certainly take care of nature much more than the state,” presented by Petr Stýblo. He cites the trend of not mowing lawns as an example. When grass is taller, it holds water more easily, is cooler, and becomes a natural home for insects and animals. At the state level, the situation is far worse. Laws are said not to be written to protect nature.
“When nature gets in the way, some lobby wins permission to destroy it,” criticizes the conservationist and adds: “Local people want nature. When they can, they protect themselves through the municipalities.” They say that the employees cannot see nature from their city offices at the regional offices. “On the state level, conservationists are losing one battle after another,” adds Petr Stýblo. It is said that only when people begin to feel the effects of the climate crisis “on their own skin” will they become more ecological.
How quickly does the temperature rise in a car in direct sunlight? Videohub
The municipality is betting big
“Klika change is useful not only in Prague, but also in other metropolises for a long time, and we are already preparing for better temperatures in the world,” Tadeáš Provazník, the municipality’s press spokesman, tells Blesk. In recent months, the city has adopted a number of strategies, for example the Climate Plan hl. m of Prague by 2030. “We also pay close attention to the proportion of vegetation elements and green areas in the built-up area, especially in the wider center of Prague,” Provazník adds.
Even though they grow like mushrooms after the rain, it is said that snails and other similar water features in the streets are not supposed to reduce the temperatures in the city in the long term, but serve to cool the city temporarily (especially in the summer months) and of course to cool the inhabitants in the streets of the city. The municipality is investing in the revitalization of orchards and courtyards, as well as the planting of new trees, the reconstruction of parks, squares and waterfronts. The snail and the drinking bottle are said to be only an accessory.
“One specific preference would, from our point of view, be effective, therefore trying to increase the temperature related to climate change in several mentioned ways,” answers Provazník. From 2020 to 2024, more than 200 city projects are “launched”. “We take care of parks and greenery to a greater extent and plant new trees, and over the last four years, about half a million new trees have been planted in Prague. We purchase electric cars for the capital and city organizations, thereby reducing emissions, and we support car sharing and bicycle transport to a greater extent,” he adds in conclusion.
The City Hall of Prague 2 has placed new snails in the streets. (2021)
Author: ÚMČ Prague 2