How to build a resilient city?
According to the UN, the urban population will increase to around 68% of the world's population by 2050, compared to about 56% today and compared to less than 30% in 1950. We can see how challenging it can be for the sustainable growth of cities. Forecasts regarding the spatial expansion of cities in times of the climate crisis give rise to enormous pressure on the need for pro-ecological activities and sustainable development of urban areas. The new urban areas that will change the current green fields both with old urban structures must be ready for extreme weather conditions: floods, droughts, and heat waves.
Impermeable materials include asphalt or concrete, the basic building materials of cities. These surfaces affect water retention in the city and lead to negative hydrological influence on urban areas.
Cities are 60 – 90% impervious
Appropriate implementation of green infrastructure supports the collection and filtering of water by reducing impervious areas in cities. Building green infrastructure increase biodiversity and leads to the mitigation of the harmful effects of the urban heat island phenomenon.
These should be planned appropriately to the scale of the city and combined into a system of tools to improve the functioning of the microclimate. Preventing the impacts of extreme weather conditions: urban stormwater or long periods of droughts. It is an essential element of modern urban planning.
The planners aim to design a space that allows you to create conditions that neutralise extremes and help you use them to your advantage in functioning.
Green urban infrastructure introduces many functions that positively affect the natural functioning of the city. For example:
Biological and physical filtration of water
Increased water infiltration into the soil
Water retention in the environment
Due to the increase in the probability of urban cataclysms, it is necessary to plan solutions to mitigate the danger of weather extremes, which can have a dramatic course, bringing victims and material damage.
Developing a defense mechanism for the urban ecosystem is crucial for minimising the effects of these phenomena and is the most important tool of contemporary spatial planning, including the conscious shaping of green urban infrastructure.
The idea of a "resilient city" should be a synthesis of lessons learned from crises and means the ability of cities to react flexibly and be able to change in changeable conditions.
Savings in the city budget
The solutions of the Green Stormwater Infrastructure (GSI) serve to relieve the traditional - gray infrastructure, allowing it to better functioning during heavy precipitation, which directly leads to
Appropriately selected plant species with the ability to biofiltration rainwater support the operation of rainwater drainage systems in many cities and bring measurable financial benefits to municipal budgets.
Accurate location of urban vegetation for pre-filtration of the water for creating water free of pollutants, in a smaller amount, enters the sewage systems of cities. The growing popularity of similar solutions, due to relatively low costs, is alternative to traditional engineering solutions in the city, and at the same time, they allow for water retention.
These solutions also reduce financial outlays by limiting the local floods caused by the increased frequency of extreme weather events in urban areas. It is one of the main reasons for the popularity of implementing such solutions in many cities.
New urban vegetation is beneficial for the physical and mental health of the citizens. These areas improve air quality, introduce shade - extremely valuable during hot weather, and increase contact with nature in densely urbanised places, where most often there are places devoid of urban greenery, which is good for health and reduces the risk of hospitalisation.
Reduction of the amplitude of surface and air temperature also contributes to extending the service life of urban infrastructure - we will describe it in the next article, so we encourage you to:
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Author: Maciej Jurzyk | Oasis City Lab 08.05.2023
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Urban flood, source: unslpashed.com
The imperviousness of Warsaw, impervious areas are marked in red, own studies based on Copernicus data
Scientific basis and sources:
C.S Holing (1973) Resilience and Stability of Ecological Systems
H. Landsberg (1981) The urban Climate
Arnold C.L et al. (1996) Impervious surface coverage: The emergence of a key environmental indicator
J. A. Sobrino, N. Raissouni (2010) Toward remote sensing methods for land cover dynamic monitoring: Application to Morocco
Ban. Y (2016) Multitemporal Remote Sensing: Methods and Applications
T. Oke (2017) Urban Climates
IRMiR (2020) Miasta wobec zmian klimatu