Nature-based solutions for watershed management: An investigation on water-related ecosystem services delivery at multiple spatial scales
Mariana Marchioni, Franco Raimondi, Gianfranco Becciu, Claudia Dresti
Abstract
• Nature-Based Solutions modify the flow of water-related Ecosystem Services for stormwater retention. • “Water flow” and “water quality regulation” Ecosystem Services were assessed for urban watershed. • Ecosystem Services assessed through Rainfall-runoff, Build-up and wash-off and 1D steady flow modelling. • Combining different types of Nature-Based Solutions techniques yields better performances than a single type. • Nature-Based solutions enhance co-benefits related to water quality, microclimate and biodiversity. 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.