Water Infrastructure Ressources (Institute)

IWA-II

Integrated Management of Urban Water Resources to Promote Blue-Green Infrastructures II

Project duration: 01/2022 - 12/2023

Departments in charge:

siwawi
rewa

Persons in charge:

Funding:

  • Deutscher Akademischer Austauschdienst (DAAD)

Project partner:

  • Universidade Federal do Mato Grosso do Sul (Brasilien)

Project description:

To strengthen the urban climate and increase the sustainability and resilience of urban areas, integrated management of urban water resources and the nutrients and pollutants they contain is needed. Especially in emerging economies such as Brazil, uncontrolled urban growth into "megacities" leads to overloading of existing gray infrastructure (e.g., overloading of wastewater treatment plants and sewer networks, etc.) and overuse of conventional water resources (such as groundwater, spring water, bank filtrate, river water, or lake or reservoir water), which is significantly exacerbated by the negative consequences of climate change, as increasingly felt in Germany and worldwide. All this results in the need to apply sustainable urban water resource management to urban infrastructure in order to improve the urban climate and increase the resilience of settlement infrastructure.

The targeted application of resource-based approaches (such as water and nutrient cycling, use of secondary sources for resource recovery, resource efficiency, etc.) can contribute to strengthening urban resilience and upgrading urban blue-green infrastructure. Blue-green infrastructures include a network of natural and semi-natural areas that provide essential ecosystem services, taking into account water and vegetation elements. They thus offer a way to counteract the consequences of climate change, which manifest themselves, for example, as weather extremes such as heavy rainfall and associated flooding or prolonged periods of drought. Especially during hot spells, blue-green infrastructure can provide cooling through evaporation or shade, among other benefits. Maintaining and expanding urban blue-green infrastructure also relieves pressure on existing gray infrastructure, such as the sewer system and central water and wastewater treatment plants, while combating the negative impacts of climate change and limiting uncontrolled emissions of pollutants into the environment. Growing populations, as well as surge loads from heavy rain events, regularly cause flooding of sewer networks, overloading of wastewater treatment plants, and thus uncontrolled discharge of pathogens and pollutants into urban areas and the environment. The Corona pandemic has made this issue even more relevant in the past year.

Even though the upgrading of urban blue-green infrastructures enables both the creation of retention areas for heavy precipitation and an increased evaporation or cooling capacity in the city, as well as bringing a number of other positive effects, the maintenance of this network of natural and near-natural elements creates a significant additional demand for water that must be met. For this purpose, in addition to intermittent precipitation water, whose availability is also directly negatively affected by climate change, other urban water resources, such as domestic and commercial graywater flows, must also be tapped and made available for various climate-impacting uses (irrigation of greenery, evapotranspiration) as well as other uses (commercial service water use, toilet flushing, etc.) in order to simultaneously mitigate the negative impacts of climate change and relieve pressure on existing infrastructure. In the case of graywater, there is an increased need for treatment compared to rainwater in order to achieve the quality required for the respective intended use, but on the other hand, graywater flows occur almost continuously, which is why they can be used for irrigation without long storage times after treatment and, if necessary, hygienization, or can be fed to other uses and thereby contribute directly or indirectly, e.g. by relieving the burden on conventional water resources, to regulating the microclimate. The sole use of precipitation water as irrigation water is coupled with increased demand for storage volume due to its discontinuous occurrence and the already increased water consumption during long periods of drought, and is hardly feasible in confined urban areas. Nevertheless, combined graywater and rainwater harvesting can be beneficial. In addition to use as irrigation water, water resources treated to the required quality of use should also be available for service water use in residential areas (e.g. toilet flushing) and/or commercial areas (e.g. cleaning purposes), which again results in a reduction of conventional fresh water resources and thus promotes the sustainable use of water as a resource in urban areas.

Within the framework of various measures, country-specific differences and similarities in the occurrence and composition of the urban water resources under consideration and in risks associated with their use in Brazil and Germany will be investigated. Through joint research and further development of existing technologies studied by the research groups of both countries, as well as through the knowledge developed in the project on impacts on adjacent systems (users, environment, resources, residuals, existing infrastructure), innovative research in the field of treatment and use of urban water resources will be achieved. By all measures involving the young scientists in an international environment with top-class scientists and by offering them a platform to develop and present their results within the framework of the project, PhD students of both groups will be specifically supported.