Martone, Ivo (2020) Field study on hydrodynamic drivers of magnitude and spatial patterns of hyporheic exchange at river confluences. [Tesi di dottorato]

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Tipologia del documento:	Tesi di dottorato
Lingua:	English
Titolo:	Field study on hydrodynamic drivers of magnitude and spatial patterns of hyporheic exchange at river confluences
Autori:	Autore Email Martone, Ivo ivo.martone@unina.it
Data:	12 Marzo 2020
Numero di pagine:	182
Istituzione:	Università degli Studi di Napoli Federico II
Dipartimento:	Ingegneria Civile, Edile e Ambientale
Dottorato:	Ingegneria dei sistemi civili
Ciclo di dottorato:	32
Coordinatore del Corso di dottorato:	nome email Papola, Andrea papola@unina.it
Tutor:	nome email Gualtieri, Carlo [non definito]
Data:	12 Marzo 2020
Numero di pagine:	182
Parole chiave:	environmental hydraulics; river confluence; confluence hydrodynamics; hyporheic exchange; vertical hydraulic gradient; heat tracing; hydraulic conductivity
Settori scientifico-disciplinari del MIUR:	Area 08 - Ingegneria civile e Architettura > ICAR/01 - Idraulica
Depositato il:	19 Mar 2020 16:37
Ultima modifica:	08 Nov 2021 12:21
URI:	http://www.fedoa.unina.it/id/eprint/13135

Abstract

Confluences are connections in riverine networks characterized by complex three-dimensional changes in flow hydrodynamics and riverbed morphology, and are valued for important ecological functions and hence guide the management and restoration of the whole river environment. This physical complexity is often investigated within the water column or riverbed, while few studies have focused on hyporheic fluxes, which is the mixing of surface water and groundwater across the riverbed. This study aims to understand how hyporheic flux across the riverbed is organized by confluence physical drivers. Field investigations were carried out at two low gradient, headwater confluences in Marcellus, New York, USA over 8 months, beginning from September 2018 to May 2019. The study measured channel bathymetry, hydraulic permeability, and vertical temperature profiles, as indicators of the hyporheic exchange due to temperature gradients. Confluence geometry, hydrodynamics and morphodynamics were found to significantly affect hyporheic exchange rate and patterns. Local scale bed morphology, such as the confluence scour hole and minor topographic irregularities, influenced the distribution of bed pressure head and the related patterns of downwelling/upwelling. Furthermore, classical back-to-back bend planform and the related secondary circulation probably affected hyporheic exchange patterns around the confluence shear layer. Finally, even variations in the hydrological conditions played a role on hyporheic fluxes modifying confluence planform, and, in turn, flow circulation patterns.

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