Tecnalia presents the results of the Green Anoeta case study and proves the importance of nature-based solutions when adapting cities to climate change
Modelling exercises for a micro-scale simulation of thermal comfort and surface runoff have been carried out in the framework of the LIFE IP Urban Klima 2050 and ECOINNOVADOR Estudio projects to improve surface runoff with nature-based solutions.
On 10 November, Tecnalia presented the results of the modelling exercises for the micro-scale simulation of thermal comfort and surface runoff in the Green Anoeta area to various departments of the Donostia/San Sebastián City Council.
These modelling exercises aim to analyse the effectiveness of urban projects that include nature-based solutions (NbS) to address the challenges facing cities in the context of climate change.
The exercises carried out at Green Anoeta combine the results of two applied research projects: the assessment of the effectiveness of nature-based solutions to improve thermal comfort in climate change scenarios (in the context of the LIFE URBAN KLIMA 2050 project, specifically action C4.1) and the assessment of the effectiveness of nature-based solutions to improve surface runoff and flood prevention (in the context of the ECOINNOVADOR Estudio project to improve surface runoff by means of nature-based solutions).
The modelling exercises yield the following results in the comparative analysis between the project’s situation (optimal scenario) and the baseline situation (current urban design):
- More comfortable cities: 71% of the area improve its thermal comfort indicators. There will be areas where there is an improvement of up to 5 °C, especially where nature-based solutions are implemented.
- Residents’ health: the project will reduce the areas at low risk of hyperthermia. 19% decrease in the area under PET levels compatible with increased risk of hyperthermia for residents.
- Volume of water retained by NbS: NbS have an influence on the permeability of the soil and the increased infiltration capacity of the soil. A total of 650 m3 of water is retained in all sub-basins due to the influence of the NbS. (Comparison between baseline and optimal feasible scenario, without CC).
- Runoff in sub-basins: NbS have an influence on the reduction of surface runoff. A decrease of 4.55% of the total runoff volume is recorded in the study area (optimal feasible scenario, without CC).
- Sewer system: The main runoff affects the capacity of the urban drainage network absorption points. Decrease of 42% (19) wells subject to flooding in the study area (optimal feasible scenario, without CC).
- Flooded surface at Anoeta: Surface runoff and saturation of the drainage network has an influence on the flooded surface. Reduction of 25% (750 m2) of the flooded area, as a result of the observation of the wells (optimal feasible scenario, without climate change).
- Volume of water retained by other rainwater retention features: Other solutions for rainwater retention may be considered. 7,000 m3 of water retained in the (6) retention basins and the wet roof in this project. (Comparison between baseline and optimal feasible scenario, without climate change).
The results at Green Anoeta show the importance of nature-based solutions in the adaptation of cities and highlight that their implementation is more effective in climate change scenarios than under current climate conditions, which means that they are cost-efficient.
As a result of these exercises and others with a similar scale of application in Bilbao and Vitoria, the lessons learnt will be used to create a guide that will enable the integration of adaptation to climate change as a vector for decision-making in urban design processes.