Assessing the Climate and Hydrological Effects of Blue-Green Infrastructure in Urban Brownfield Regeneration

The rapid human population growth is driving profound transformations in urban development. Expansions driven by land revenues and inadequate land use policies are driving the increase in frequency and intensity of the urban heat island (UHI) effect and urban flooding. These detrimental consequences are exacerbated by the climate change, that is causing more frequent and more intense extreme weather events. The installation of blue-green infrastructures (BGI) is a promising strategy to achieve sustainable development, promote inclusivity, decrease inequalities, combat climate change and halt biodiversity loss.

Scientists have developed numerical models capable of simulating sustainable stormwater management and the temperature response to the given land covers. Only recently has their combination been explored and it is essential to evaluate co-benefits as well as trade-offs. In this study, we integrate in one framework, with a one-way feedback, the inputs and outputs of two globally used BGI planning-support modeling tools (i.e., SWMM and TARGET). Importantly, we refined TARGET so that remote sensing data can be exploited. In practice, we introduce the possibility to account for the spatial variability of land cover properties (e.g., albedo values) for more accurate modelling and of Land Surface Temperatures, for validation purposes. The framework allows us to understand how hydraulic elements and land use change affect stormwater quantity management as well as urban temperatures.

We apply this framework to a mixed industrial/residential neighborhood in the Municipality of Modena, a city with about 180,000 inhabitants located in the northern part of Italy, in the Po Valley. The area is particularly suited for the study given the precedent sprawling of industrial buildings in the historical rural area, which nowadays has been incorporated in the city and surrounded by residential areas.

The analysis compares the current urban configuration with alternative scenarios involving the retrofit of industries and conversion of abandoned industrial brownfields into BGI. The results demonstrate that brownfield regeneration through BGI can deliver measurable co-benefits for urban drainage and microclimate at the city scale. These findings support multi-objective BGI planning as a viable strategy for climate change mitigation and adaptation in medium-sized cities.