Ecosystem services are increasingly being considered in decision-making with respect to mitigating future climate impacts. In this respect, there is a clear need to identify how nature-based solutions (NBS) can benefit specific ecosystem services, in particular within the complex spatial and temporal dynamics that characterize most river catchments. To capture these changes, ecosystem models require spatially explicit data that are often difficult to obtain for model development and validation. Citizen science allows for the participation of trained citizen volunteers in research or regulatory activities, resulting in increased data collection and increased participation of the general public in resource management. Despite the increasing experience in citizen science, these approaches have seldom been used in the modeling of provisioning ecosystem services. In the present study, we examined the temporal and spatial drivers in nutrient delivery in a major Italian river catchment and under different NBS scenarios. Information on climate, land use, soil and river conditions, as well as future climate scenarios, were used to explore future (2050) benefits of NBS on local and catchment scale nutrient loads and nutrient export. We estimate the benefits of a reduction in nitrogen and phosphorus export to the river and the receiving waters (Adriatic Sea) with respect to the costs associated with individual and combined NBS approaches related to river restoration and catchment reforestation.