In highly urbanized contexts, green roofs are increasingly studied and utilized as sustainable solutions for capturing and modulating runoff to achieve hydraulic and hydrological invariance. They reduce the total volume of runoff and mitigate the ridge flow returned to the sewer system through two hydrological processes: rainfall retention, which is the permanent removal of stormwater, and runoff detention, which is the transient storage of rainfall. Both processes are conditioned by the physical and hydraulic properties of the substrate or culture medium, a key aspect that is still little investigated. This thesis represents a contribution to fill the gap of knowledge in the field of hydraulic characterization of substrates for green roofs, with a view to environmental sustainability and circular economy. Through a comprehensive and multi-scalar methodological approach, this thesis assessed: i) the effects of adding different organic soil amendments, such as compost, vermicompost, and pruning residues, on the soil water retention curve and the related indicators of soil physical quality (SPQ); ii) the assessment of the retention and detention capacities of a volcanic medium suitable for green roof system under intense rainfall events; iii) the changes in substrate hydraulic characteristics of a prototype green roof plot throughout the lifecycle The soil water retention curve, θ(h), was determined by the tension hanging water column apparatus and the pressure plate extractors. Measurements of the hydraulic conductivity fuction, K(h), were conducted by either the evaporation method and the MiniDisk Infiltrometer (MDI). A needle rainfall simulator was applied to determine the retention/detention of green roof microcosms assembled with different drainable layers) a field assessment of substrate hydraulic changes throughout the lifecycle on a prototype green roof plot. The hydraulic conductivity curves, K(h), were determined by using the MiniDisk Infiltrometer (MDI).All the amendments applied demonstrated a positive impact on the hydraulic properties of the substrates, significantly enhancing the soil water retention and improving physical quality. The results underscore the potential of organic amendments to improve soil structure and optimize water management, as they increased plant-available water in coarse-textured soils and improved the air/water balance in fine-textured soils. However, soil texture and aging of the substrate proved to influence the soil physical quality, therefore careful consideration must be given to soil texture and the temporal variability of the beneficial effects on the soil physical quality, which tend to diminish over time, when the selecting selection of the amendment, determining its optimal dosage, and planning the application schedule. Moreover, the volcanic medium analyzed has demonstrated a favorable hydrological response, thus encouraging its use in combination with amendments like compost or vermicompost. This establishes it as an effective and sustainable choice for the mineral component of a green roof substrate in Mediterranean climates, especially when it is combined with a well-balanced mixture of organic materials such as compost or vermicompost.
(2025). Hydraulic characterization of eco-sustainable growing substrates for urban green infrastructures.
Hydraulic characterization of eco-sustainable growing substrates for urban green infrastructures
BONDI', Cristina
2025-01-29
Abstract
In highly urbanized contexts, green roofs are increasingly studied and utilized as sustainable solutions for capturing and modulating runoff to achieve hydraulic and hydrological invariance. They reduce the total volume of runoff and mitigate the ridge flow returned to the sewer system through two hydrological processes: rainfall retention, which is the permanent removal of stormwater, and runoff detention, which is the transient storage of rainfall. Both processes are conditioned by the physical and hydraulic properties of the substrate or culture medium, a key aspect that is still little investigated. This thesis represents a contribution to fill the gap of knowledge in the field of hydraulic characterization of substrates for green roofs, with a view to environmental sustainability and circular economy. Through a comprehensive and multi-scalar methodological approach, this thesis assessed: i) the effects of adding different organic soil amendments, such as compost, vermicompost, and pruning residues, on the soil water retention curve and the related indicators of soil physical quality (SPQ); ii) the assessment of the retention and detention capacities of a volcanic medium suitable for green roof system under intense rainfall events; iii) the changes in substrate hydraulic characteristics of a prototype green roof plot throughout the lifecycle The soil water retention curve, θ(h), was determined by the tension hanging water column apparatus and the pressure plate extractors. Measurements of the hydraulic conductivity fuction, K(h), were conducted by either the evaporation method and the MiniDisk Infiltrometer (MDI). A needle rainfall simulator was applied to determine the retention/detention of green roof microcosms assembled with different drainable layers) a field assessment of substrate hydraulic changes throughout the lifecycle on a prototype green roof plot. The hydraulic conductivity curves, K(h), were determined by using the MiniDisk Infiltrometer (MDI).All the amendments applied demonstrated a positive impact on the hydraulic properties of the substrates, significantly enhancing the soil water retention and improving physical quality. The results underscore the potential of organic amendments to improve soil structure and optimize water management, as they increased plant-available water in coarse-textured soils and improved the air/water balance in fine-textured soils. However, soil texture and aging of the substrate proved to influence the soil physical quality, therefore careful consideration must be given to soil texture and the temporal variability of the beneficial effects on the soil physical quality, which tend to diminish over time, when the selecting selection of the amendment, determining its optimal dosage, and planning the application schedule. Moreover, the volcanic medium analyzed has demonstrated a favorable hydrological response, thus encouraging its use in combination with amendments like compost or vermicompost. This establishes it as an effective and sustainable choice for the mineral component of a green roof substrate in Mediterranean climates, especially when it is combined with a well-balanced mixture of organic materials such as compost or vermicompost.File | Dimensione | Formato | |
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