Let’s start with language, as it shapes consciousness. In many cities, we find programs or goals written into strategies for drainage. This means – in a nutshell – building an oversized infrastructure that discharges rainwater to a receiver (in accordance, we should add, with the standards and technical requirements of the infrastructure), which – on the one hand – uses its predicted capacity relatively infrequently throughout the year, and on the other hand – we can never be sure that there will not be a rainfall so intense that the built gray infrastructure will not be able to accommodate it. In addition, the increasing sealing of urban surfaces is intensifying the volume and intensity of runoff.
Rainwater picks up pollutants from sealed surfaces and discharges them into receiving waters, often without treatment or using only separators, which has a negative impact on water quality. Prof. A. Janucha-Szostak called this way of dealing with rainwater and snowmelt “from the cloud to the pipe,” which perfectly reflects the situation.
Rainwater – challenges
It is therefore necessary to move away from the practice of urban drainage to systems that manage rainwater and snowmelt. It’s more than just drainage. We manage resources, and we discharge wastewater. That’s why it’s so important to promote thinking about rainwater and snowmelt not as a problem, but as a resource. The main challenge is to stop precipitation at the point of occurrence to prevent accelerated runoff.
This will make it possible to take advantage of all the opportunities offered by the presence of water in the city. We are, of course, talking about the implementation of Nature Based Solutions (NBS) and Blue Green Infrastructure (BGI) . In turn, we omit consideration of the difference between NBS and BGI. Let’s call this approach “from the cloud to nature, without the pipe.” Catalogs of blue-green infrastructure and catalogs of good practices can be easily found in Internet resources, including in Polish, so I will not cite classifications or examples of specific solutions.
Blue-green infrastructure is a network of strategically planned natural and semi-natural or completely human-transformed areas that, through the use of natural processes such as shading, effects on air movement, seepage, evaporation, runoff and others, lead to improvements in environmental quality, especially urban, reduce pollution, reduce surface runoff, increase soil and plant retention, reduce local temperatures during hot periods, etc., and support socio-cultural functions.
Rainwater – the benefits of managing it
Numerous scientific studies indicate that managed rainwater and snowmelt provide benefits far greater than if it is discharged (I will present these in future posts). However, due to the difficulty of valuing them, as well as the separation of actors who bear the costs and reap the benefits, common in externalities , their emphasis is often forgotten. While the literature on external costs is extensive, that on external benefits is somewhat more modest, which is precisely what we are dealing with in the case of rainwater management.
In simple terms, externalities are involved when the activities of one entity affect the operating conditions of another entity, and there is no automatic compensation between the entities. Impacts can be positive or negative, unilateral, multilateral or reciprocal. If we can determine their value, we call them external benefits or costs. The introduction of external costs into the offender’s account is called internalization of external costs.
Various approaches, analyses and valuations can be found in the literature. However, I wanted to focus on cataloging and systematizing the benefits of urban rainwater management. This catalog is not closed, but as broadly as possible indicates benefits in various categories: ecological, functional, economic, landscape, socio-cultural and legal .
Rainwater – selected benefits
|organic||Restoration, protection of aquatic ecosystems, improvement of hydrological conditions;reduction of pollution pressure on rainwater recipients;soil conservation;protection, restoration of plant and animal habitats, preservation and restoration of biodiversity;improvement of the microclimate in the city, reduction of pollution;minimization of the negative impact of investments on the environment;increase and creation of migration corridors.|
|functional||Supporting flood protection;protecting water from pollution, pretreating discharged rainwater;reducing the intensity of maximum flows in the receiving basin;protecting groundwater and in receiving basins from pollution;supporting drought protection;reducing the risk of wildfires;reducing the urban heat island effect;improving air quality and microclimate in the city;irrigating plants, green spaces.|
|economical||Increase in property values;reduction in city maintenance costs (including irrigation of green spaces and cooling of squares and tracks, creation and maintenance of the transportation network);reduction in energy consumption;reduction in property damage and losses caused by flooding,reduction in property losses and compensation costs;reduction in the cost of creating and maintaining gray infrastructure;increased competitiveness and attractiveness of degraded areas as a result of rehabilitation in accordance with the needs of residents;increase in economic activity in the sphere of catering services and supporting sports and tourism activities in the vicinity of new, attractive green spaces with water.|
|scenic||Urban renewal;integration of urban space, reducing fragmentation;creation of additional space for recreation and sports.|
|socio-cultural||Improving living conditions in the city (lowering the temperature, reducing air pollution and the amount of allergens in the air);improving the health of residents;supporting cooperation between authorities and residents, public participation, responsibility for common areas;protecting unique local assets;creating places to spend time together, activating and integrating residents;promoting equal access to resources, egalitarianism, targeting vulnerable social groups: children, the elderly;reducing moral damage (resulting from loss of property and post-flood trauma);increasing or maintaining opportunities for recreational use of water reservoirs.|
|legal||Fulfilling international obligations;meeting national requirements for water protection.|
Implementation of blue-green infrastructure
It should be clearly emphasized that in the implementation of blue-green infrastructure there must be an effect of scale, one, two or even ten “installations”, although locally they will generate positive changes, at the scale of the city will not produce noticeable effects. Implementation of these solutions must be systemic, planned and required, and even supported. Only the integrated action of hundreds or even thousands of facilities will cause the city to start behaving like a sponge, absorbing rainwater and snowmelt, reducing the risk of flooding, including rapid urban flooding and flooding from sewers. On the other hand, it becomes more resistant to the effects of drought and heat.
This means that the implementation of BGI has an impact on reducing the effects of urban heat island, urban smog island and even urban noise island. The social effects of implementing blue-green infrastructure, community involvement, anti-exclusion effects, etc., cannot be underestimated. At the same time, as an environmental economist concerned with green and climate investments, I can’t help but reflect that investments in nature-based solutions are anomalies for financiers. Here, there is no reduction in value over time; on the contrary, in most cases, an increase is observed, something that modern investment efficiency calculus cannot cope with for the time being. But that’s a topic for further consideration.
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.
In the article, I used, among others. From the works:
 Communication from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions Green Infrastructure – Enhancing Europe’s Natural Capital /* COM/2013/0249 final */.
 More widely: Śleszyński J., Ekonomiczne Problemy Ochrony Środowiska (Warsaw: Paries, 2000); Fiedor B. et al, Podstawy ekonomii środowiska i zasobów naturalnych (Warsaw: C.H. Beck, 2002).
 Rosiek K., Sealed surface levies as an instrument for sustainable management of rainwater and snowmelt, Prace Naukowe Uniwersytetu Ekonomicznego we Wrocławiu, Ekonomia środowiska i polityka ekologiczna, Ekonomia środowiska i polityka ekologiczna.453 (2016), 270-81; Ksymena Rosiek, ‘Wody Opadowe Jako przedmiot Gospodarowania’, Economy in Practice and Theory, vol. 44, 3, 2016, 61-76 <http://dx.doi.org/10.18778/1429-3730.44.05>.
 Rosiek K., Sealed surface charges as an instrument for sustainable management of rainwater and snowmelt, Prace Naukowe Uniwersytetu Ekonomicznego we Wrocławiu, Ekonomia środowiska i polityka ekologiczna.453 (2016), 270-81; Rosiek K., Wód Opadowe Jako przedmiot Gospodarowania, Gospodarka w Praktyce i Teorii, vol. 44, 3, 2016, 61-76 <http://dx.doi.org/10.18778/1429-3730.44.05>.