On the main methods to estimate the soil hydraulic properties of the Nature-based solutions

Nature-based solutions (NBS) are very popular techniques to solve several problems in urban areas. These techniques proved several benefits such as stormwater management, heat island reduction, air and water quality improvement, and biodiversity enhancements. Among these techniques, are green roofs, green walls, grid permeable pavement, bio-retention basins, constructed wetlands, and infiltration trenches. Although the benefits of these techniques are significant, their use is still limited and not widespread because the hydraulic characteristics of the materials involved in their construction are often unknown. Most of these NBS has the soil, or any porous media, as the main layer. In this way, the definition of the hydraulic properties of the porous media involved in the construction will help designers, researchers, and practitioners to choose the best materials for the purpose. In this way, this study will explore the main methods to define the hydraulic properties of a porous media, both in situ and in the laboratory, comparing the accuracy of the results achieved, time-consumg, data measurement, and boundary conditions.