The AMAREX work package 3 "Functional extension of blue-green infrastructure (BGI) to prevent heat and drought" is being worked on by the Institute for Sanitary Engineering, Water Quality and Solid Waste Management at the University of Stuttgart. Blue-green infrastructure (BGI) refers to various measures for the natural handling of rainwater in settlements. Rainwater use, local infiltration, and evaporation are primarily intended to reduce or avoid high and rapid rainwater runoff. Positive effects of BGI are improved groundwater recharge and reduction of heat stress through evaporative cooling. However, the effect of BGI as a precaution against heat and drought is limited, since conventional systems are not technically designed for the larger and manageable storage volumes required for this purpose.
With the expected increase in extreme heat and drought phases as an effect of climate change, urban heat and drought prevention is a highly relevant municipal task. This work package investigates and evaluates what effect decentralized BGI can have for heat and drought prevention if they are functionally adapted and optimized as BGI-U systems - i.e. by adding manageable storage volumes for usage - to the requirements of heat and drought prevention. For this purpose, the practical planning and implementation potentials will be investigated and evaluated in pilot areas. By means of long-term studies with the green type facade greening, the hitherto missing database on climate-dependent temporal and qualitative irrigation requirements is being developed in cooperation with project partner HELIX Pflanzensysteme GmbH.
Firtsly, BGI-U must be clearly defined from a technical point of view. This is done by developing a catalogue of measures to describe the basic application and operational requirements of BGI-U systems. Furthermore, it will be investigated where and under which boundary conditions BGI-U can be located in urban areas and how this can lead to the decrease of water shortage situations in the environment during heat stress and drought phases. For this purpose, the potential use of BGI-U systems for local precaution against heat stress and drought is determined for an investigation area in Cologne with a geographic information system (GIS), the corresponding geodata (digital terrain model, cadastral and area information, green types) and climate data (precipitation, temperature) identified in particular through the provision of process water for the irrigation of urban green spaces.
An existing water intake-storage-provision (WSP) model is to be further developed using results from the comparative model simulations from WP 2 and supplemented by a module for the treatment effect of BGI-U systems to form a WTSP model. This model, furthermore, needs to be ultimately validated in order to be able to more precisely calculate the effect of BGI-U systems with regard to their storage, treatment and supply capacity of process water to prevent heat stress and drought.
By means of long-term investigations on the evaporation rate and plant growth of the green type facade greening, a detailed database on climate-dependent temporal and qualitative irrigation requirements is being developed in cooperation with the project partner HELIX Pflanzensysteme GmbH. Gaps in the data for other green types are being closed in cooperation with the project partner StEB Cologne, the Office for Landscape Maintenance and Green Spaces of the City of Cologne, and the Horticultural/Green Spaces Offices in Frankfurt and Karlsruhe.
A very characteristic integral approach in AMAREX is the common transfer of results of work package 3 with the results of work packages 2 and 4 into a web tool. Thus, subsequent to the project, municipalities and authorities will have an effective tool to assess the potential of BGI-U systems for the precaution against heat stress and drought as well as for the prevention of flooding for their own study areas.
In the currently ongoing first project phase, the catalogue of BGI-N systems is being compiled. Furthermore, in cooperation with the project partner StEB Cologne, the GIS potential analysis is also being developed for a study area in Cologne. At the same time, 3 retention cisterns will be connected to different areas -green and bitumen flat roofs as well as a low-traffic area- on the outdoor area of ISWA and the facade greening elements of the project partner HELIX Pflanzensysteme GmbH will be set up. In a long-term test, the facade greening elements are then to be irrigated with the different surface runoffs temporarily stored in the retention cisterns.