Is it still a hot summer or already a drought in the city?

In 2022. Europe experienced the hottest summer in the history of measurement [1]. This year has seen the hottest days and the hottest week [2]. At the same time, other regions are plagued by heavy rainfall and flooding [3]. What’s going on with this weather? Such questions are commonly heard.

In our climate zone, climate change is causing more violent and extreme weather events. We see that this is not a topic for future generations, but for now, right now. The drought in the city seems to be less severe, because – so far – there has always been water on tap. In rural areas, residents have been experiencing declining water levels in wells or even their disappearance for years, as well as crop losses. The drought in the city is not so visible, but does that mean it is not there? Things are not made easier by “social memory”: it is much better at recreating episodes of flooding and waterlogging, which are often severe in cities, while droughts are much less well remembered – water supplies are not stopped, and when it is really hot, cooling water curtains are set up.

Drought in the city

Drought in the city is not just about dry, sun-scorched lawns. It’s also worse air quality (more dust, photochemical smog), it’s an urban heat island problem (concrete and other surfaces, such as roofs, heat up, hold heat longer and give it back at night, making it very difficult for the air to cool down), it’s a health risk for children, the elderly and those with civilization diseases. After all, this is the city we want to escape from.

And cities are expanding, vacant spaces are being developed, trees are being removed (because the leaves are getting dirty, because they restrict access for emergency services, interfere with the construction of the next flyover or other road project or office building). For decades, Polish cities have had the idea that a paved square is a 1) easier to keep clean, 2) a mass event can be held on it, 3) you can conveniently park your car. The process of “urban sprawl” continues unabated, with rural areas becoming suburban, “cube” driveways being laid around houses, and gardens being replaced by foil-lined and white pebble-strewn creations.

These trends make heat waves and urban drought increasingly severe, and precipitation leads to flooding (rapid urban flooding) more often and faster. Because drought and flooding are always two sides of the same coin. In addition to natural causes, human economic activities, excessive land reclamation and improper land management have a huge impact on their occurrence.

Let’s look at the data (Table 1). Seemingly, they are not alarming. According to the CSO/BDL, between 2003 and 2020 the share of built-up and urbanized area in Poland increased by only 1 percentage point.

Specification	2003	2005	2010	2015	2020	growth
	%	%	%	%	%	p.p.	km2
Share of built-up and urbanized area in total area	4,6	4,7	5,0	5,3	5,6	1,0	3127

However, in practice, this means that in 17 years there has been as much “concreted” area as if nearly 10 additional cities the size of Krakow had appeared! (with an area of 327 square ^kilometers each). Can you imagine them on a map of Poland?

What does the increase in built-up and urbanized area and urban drought have in common? On a sealed surface (built up with buildings, from parking lots, from streets and sidewalks), rainwater runs off instead of soaking in. Both the terrain and (perhaps especially) the degree of sealing are important (Figure 1). In very tight areas, runoff can exceed 85%. What else is worth paying attention to in the context of urban drought? Beautifully maintained, frequently mowed lawns take in much less rainwater than wildflower lawns, the water mostly runs off them and they often need watering the very second day after a rain.

Many Polish cities are taking steps to unseal surfaces and manage rainwater. In simple terms, two main currents can be said (Figure 2). At the same time, the water stored in the tanks can be intended for later use. Here it is important to note a dichotomy: the approach that is still dominant, i.e. drainage of rainwater, and in opposition to it, the management of rainwater as close as possible to where the rainfall occurs. In summary, the discharge of rainwater is not considered to be its management (although one can find different divisions in the literature).

Attempts to counter drought in the city can – and should – be on a variety of scales, but this column chooses to focus on actions that any resident can take that contribute to reducing their environmental pressure and preventing drought. Of course, a lot depends on where a person lives, but you should always try.

In single-family housing:

• Collecting rainwater from the roof of the building for watering plants in the garden (saving on water bills);
• changing the way plants are planted (always in holes, depressions, so that rainwater does not run off so quickly);
• Turning lawns into perennial gardens, ornamental grasses, etc. – They are beautiful and require less maintenance than a lawn;
• Removing the film – using cover plants;
• Using natural materials to reduce evaporation and weed growth, such as coconut mats, cardboard boxes (and preferably both);
• Less frequent mowing of lawns;
• abandon the use of artificial fertilizers, which cause rapid growth of the green part, but shallow rooting, in favor of biofertilizers that promote the development and growth of plant roots, rather than the growth of the green part, so that the lawn can be mowed less often and is more resistant to drying out;
• introduction of rain gardens [4] (absolutely not ponds);
• Using water from washing vegetables in the kitchen to water plants at home or on the terrace;
• Abandoning the illegal discharge of rainwater into sewers or roadside ditches in favor of managing it on the plot (through collection or infiltration).

Drought in the city, in dense collective housing, also finds numerous opponents. Admittedly, there are fewer opportunities, but that doesn’t mean there aren’t any.

In collective housing (blocks of flats):

• Checking whether the cooperative/community/manager has a policy for greenery maintenance and whether it is in line with the city’s rules (frequency and height of mowing, timing of first mowing);
• Demand that records be changed in favor of greener ones; see if flower meadows, rain gardens, mowing only 50 cm from the curb, shrubbery instead of lawns (e.g., ground cover roses, colorful barberries and other low shrubs) can be introduced; perhaps a neighborhood planting campaign;
• Turning the balcony into a green oasis, but try to water the plants with water from washing fruits and vegetables, rinsing rice or potatoes (just make a habit of washing them in a bowl);
• to see if there is a program in the city to create community gardens, maybe this will create a common, friendly space in a close neighborhood;
• Submitting green projects to the civic budget.

Heat waves and drought in the city are becoming a real problem that affects the quality of life and well-being of residents. The best way to respond to these problems is to introduce sustainable rainwater management systems in the city based on blue-green infrastructure [5]. Every resident can make an effort to contribute less to urban drainage and therefore urban drought.

Dr. Ksymena Rosiek – researcher, teacher, employee of the Cracow University of Economics, in the Department of Sustainable Development Finance. Member of the Association of Environmental and Resource Economists. A contributor to the OEES WaterLab think tank. He specializes in sustainable development issues, with a particular interest in the city’s ecosystems, blue and green infrastructure. Stormwater management from an economic perspective in an era of climate transition, environmental costs and benefits in the context of the Circular Economy, common goods and the impact of Revolution 4.0 on the public sector are the subject of current research.

She has authored and co-authored nearly 100 scientific articles and scientific monographs, as well as publications in professional journals. Participant of international congresses in the US, Europe, Japan and South America. He has been working with research centers in Japan for years. Involved as an expert in national and international projects related to the economic aspects of water management, including in the context of climate change adaptation.

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In the article, I used, among others. From the works:

[1] https://climate.copernicus.eu/extreme-heat-widespread-drought-typify-european-climate-2022 (accessed 26.07.2023)

[2] https://climate.copernicus.eu/european-heatwave-july-2023-longer-term-context (accessed 26.07.2023)

[3] https://floodlist.com/europe,(accessed 26.07.2023)

[4] Rain garden in 5 steps http://www.gdmel.pl/images/dokumenty/9-ogrod-deszczowy-w-5-krokach.pdf (accessed July 31, 2023).

[5] Blue-Green Infrastructure for Mitigating Climate Change in Cities – Technical Catalogue, Sendzimir Foundation 2019 , https://sendzimir.org.pl/publikacje/blekitno-zielona-infrastruktura-katalog-techniczny, Green-Blue Infrastructure Catalogue. Part II. Guidelines and Solutions, Municipal Waterworks and Sewerage in Bydgoszcz, 2017, http://www.mwik.bydgoszcz.pl/index.php/2012-08-06-06-20-22/470-katalog-zielono-niebieski and K. Lejcuś, E. Burszta-Adamiak, K. Wróblewska, M. Spitalniak, D. Marczak, J. Misiewicz, J. Dobrzańska, H. Orzeszyna, Catalog of Good Practices, Ch. II – Principles for Sustainable Stormwater Management in the Built-Up Area, 2020 , https://www.wroclaw.pl/zielony-wroclaw/katalog-dobrych-praktyk-zlap-deszcz,(accessed 31-07-2023).