Nature-based solutions for watershed management: An investigation on water-related ecosystem services delivery at multiple spatial scales

The expansion of urban areas, driven by population growth and economic activities, places significant pressure on water resources, affecting both quality and quantity. Furthermore, climate change alters rainfall patterns, leading to more frequent and intense events in many cities. This increases the risk of flooding and water pollution, as drainage systems become more frequently exceeded and impervious surfaces rise. In this context, Nature-Based Solutions (NBS) offer a way to address urban and societal challenges by mimicking natural processes like infiltration and evapotranspiration, thereby promoting the Ecosystem Services (ES) delivery. This research aims to identify the most effective NBS combination to tackle urban flooding challenges, by assessing the “water flow regulation” and “water quality regulation” ES. Using hydrological modelling and ES assessments in the Seveso River watershed in Northern Italy, the study found that combining NBS for stormwater management with river restoration significantly reduces peak flow rates, discharged volumes, flooded areas and pollution, also improving the river ecological quality. Different NBS scenarios were evaluated across various spatial scales, demonstrating their ability to enhance ES. The results highlight NBS multifunctionality, not only improving “water flow regulation” and “water quality regulation” services, but also providing multiple co-benefits.