Evaluation of Flow Resistance Models Based on Field Experiments in a Partly Vegetated Reclamation Channel

Geosciences

GiuseppeFrancesco Cesare Lama¹  GiovanniBattista Chirico¹  Federico Preti²  Alessandro Errico²  Luca Solari³  Simona Francalanci³ 

[1] Department of Agricultural Sciences, Water Resources Management and Biosystems Engineering Division, University of Naples Federico II, 80055 Portici (NA), Italy;Department of Agricultural, Food, Environmental and Forestry Sciences and Technologies, University of Florence, 50144 Firenze, Italy;Department of Civil and Environmental Engineering, University of Florence, 50139 Firenze, Italy;

关键词: partly vegetated reclamation channel;    common reed;    resistance models;    vegetative chézy’s coefficient;    dcm;    composite cross section;   

DOI  :  10.3390/geosciences10020047

来源: DOAJ

【 摘 要 】

This study presents a methodology for improving the efficiency of Baptist and Stone and Shen models in predicting the global water flow resistance of a reclamation channel partly vegetated by rigid and emergent riparian plants. The results of the two resistance models are compared with the measurements collected during an experimental campaign conducted in a reclamation channel colonized by Common reed (Phragmites australis (Cav.) Trin. ex Steud.). Experimental vegetative Chézy’s flow resistance coefficients have been retrieved from the analysis of instantaneous flow velocity measurements, acquired by means of a downlooking 3-component acoustic Doppler velocimeter (ADV) located at the channel upstream cross section, and by water level measurements obtained through four piezometers distributed along the reclamation channel. The main morphometrical vegetation features (i.e., stem diameters and heights, and bed surface density) have been measured at six cross sections of the vegetated reclamation channel. Following the theoretical assumptions of the divided channel method (DCM), three sub-sections have been delineated in the reference cross section to represent the impact of the partial vegetation cover on the cross sectional variability of the flow field, as observed with the ADV measurements. The global vegetative Chézy’s flow resistance coefficients have been then computed by combining each resistance model with four different composite cross section methods, respectively suggested by Colebatch, Horton, Pavlovskii, and Yen. The comparative analysis between the modeled and the experimental vegetative Chézy’s coefficients has been performed by computing the relative prediction error (ε_r, expressed in %) under two flow rate regimes. Stone and Shen model combined with the Horton composite cross section method provides vegetative Chézy’s coefficients with the lowest ε_r.

【 授权许可】

Unknown