Lama, Giuseppe Francesco Cesare (2020) Flow resistance in open channels colonized by Phragmites australis: field experiments and modeling. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Resource language: English
Title: Flow resistance in open channels colonized by Phragmites australis: field experiments and modeling
Lama, Giuseppe Francesco
Date: 13 March 2020
Number of Pages: 109
Institution: Università degli Studi di Napoli Federico II
Department: Agraria
Dottorato: Scienze agrarie e agroalimentari
Ciclo di dottorato: 32
Coordinatore del Corso di dottorato:
Chirico, Giovanni BattistaUNSPECIFIED
Date: 13 March 2020
Number of Pages: 109
Settori scientifico-disciplinari del MIUR: Area 07 - Scienze agrarie e veterinarie > AGR/08 - Idraulica agraria e sistemazioni idraulico-forestali
Date Deposited: 20 Mar 2020 15:35
Last Modified: 31 Oct 2021 21:35

Collection description

The analysis and the prediction of the effects of the hydrodynamic interaction between water flow and riparian vegetation in natural and manmade vegetated water bodies are the main objectives of Ecohydraulics. Riparian vegetation has a paramount impact on both flow resistance and water quality in vegetated open channels. Defining the most appropriate management practice of riparian vegetation inside both natural and manmade water bodies is crucial for assuring a balance between a satisfactory level of hydraulic conveyance and a high environmental value of water. The presence of riparian vegetation significantly affects both mean and turbulent water flow fields, with important implications on oxygen production and transport of nutrients within vegetated open channels. Experimental analysis and modeling were performed in this thesis, to provide additional understanding of the hydrodynamic interaction between riparian vegetation and water flow at field scale in an abandoned reclamation channel colonized by rigid and emergent plants of Phragmites australis (Cav.) Trin. ex Steud., also known as Common reed. Different riparian vegetation management scenarios were evaluated: undisturbed conditions, partial riparian vegetation cover and total riparian vegetation removal. Field hydraulic tests were carried out for investigating the experimental cross sectional distributions of streamwise velocity and main turbulence features (Reynolds stresses and Turbulent Kinetic Energy). The outcomes of the experimental activities were employed for modeling the flow resistance of the examined vegetated reclamation channel by employing both 1D numerical simulations and literature models, which accuracies were assessed by comparing experimental and modeled vegetative global water flow resistance coefficients. In the case of partial riparian vegetation cover, a methodology based on the detailed analysis of the experimental cross sectional streamwise velocity distribution was proposed. This methodology provides estimates of global water flow resistance with prediction errors smaller than the direct application of the examined models. In the last part of the doctoral research program, the feasibility of Digital Hemispherical Photography (DHP) technology was evaluated for assessing Leaf Area Index (LAI) of mature Common reed plants to be exploited for flow resistance modeling of vegetated streams. The uncertainty of DHP-derived LAI was evaluated from a functional perspective, by estimating its impact on the uniform water flow velocity predicted with Västilä & Järvelä model. DHP proved to be a reliable technology for ecohydraulic modeling at field scale.


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