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

Abstract

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 (εr, 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 εr.

Bulk Drag Predictions of Riparian Arundo donax Stands through UAV-Acquired Multispectral Images

“…NDVI UAV map values were correlated to ground-based LAI measurements of Arundo donax portion effectively interacting with flow to obtain LAI* maps to estimate the bulk drag coefficients C D associated with 30 cross-sections identified along the examined vegetated drainage channel. It was possible applying the predictive model of vegetative flow resistance proposed by Västilä and Järvelä [4] once the experimental values of the main hydraulic and hydrodynamic features measured at the same channel's cross-sections [49][50][51][52] were known. The strong capability of UAV-acquired multispectral imagery in estimating the bulk drag coefficients C D of the examined vegetated drainage channel fully covered by 9-10 m high Arundo donax stands was then demonstrated by a comparative analysis performed between C D prediction assessed by considering the average observed and UAV-based LAI measurements at the same 30 channel's cross-sections, respectively.…”

Drone and sensor technology for sustainable weed management: a review

“…Precision agriculture relies on technologies that combine sensors, information systems, and informed management to optimize crop productivity and to reduce the environmental impact [50]. Nowadays, precision agriculture has a broad range of applications and it is employed in different agricultural contexts including pests control [51], fertilization, irrigation [52,53], sowing [54] and harvesting [55]. Precision agriculture can be effectively applied to IWM also.…”

A full‐scale study of Darcy‐Weisbach friction factor for channels vegetated by riparian species

“…In such a perspective, soil bioengineering stabilization practices (e.g., live staking, live fascine installation, vegetated geogrids, vegetated cribb walls) (Ferro, 2019b; Florineth, 2007; Gray & Sotir, 1996) can be considered a good option to manage open channels in order to guarantee healthier ecosystems and at the same time a considerable reduction of the erosive phenomena. However, the definition of a simple and accurate model for assessing the global flow resistance coefficients is still a challenging issue in soil bioengineering practices and in programming the management of riparian vegetation in open channels (Lama et al, 2020).…”

“…Lama et al (2020) tested the applicability of the model of Baptist et al (2007) and Stone and Shen (2002) for estimating the vegetative Chèzy flow resistance coefficient. The results of these models were compared with the measurements collected during an experimental campaign conducted in a reclamation channel colonized by Common reed ( Phragmites australis [Cav.]…”