PNNL

Abstract

Ecological functions and processes in the river corridor are influenced by the exchange of water, solutes, and energy between the surface stream and its catchment, and thus regulate downstream water quality [e.g., Brunke and Gonser, 1997; Krause et al., 2011; Wondzell and Gooseff, 2014; Ward, 2015]. These exchange fluxes are collectively termed river corridor exchange and integrate the stream, hyporheic zone, and riparian zone along the river network [Harvey and Gooseff, 2015]. Several recent studies have extended feature- and reach-scale findings to predict ecological functions of river corridors at basin scales relevant to resource management [e.g., Gomez-Velez and Harvey, 2014; Kiel and Cardenas, 2014; Gomez-Velez et al., 2015; Bertuzzo et al., 2017; Helton et al., 2018]. These approaches require a scaling relationship to predict river corridor exchange across space and through time. Discharge is a logical scaling factor and has been studied as a control on river corridor exchange in both space (i.e., along a network) and time (i.e., under different hydrologic conditions at a fixed location). However, discharge is an integrator of forcing at different scales and leads to potentially different predictions of river corridor exchange [Ward & Packman, 2018]. For example, increases in discharge have been found to cause increases, decreases, or no change in river corridor exchange [Morrice et al., 1997; Butturini and Sabater, 1999; Hart et al., 1999; Jin and Ward, 2005; Wondzell, 2011, 2006; Zarnetske et al., 2007; Schmid, 2008; Karwan and Saiers, 2009; Schmid et al., 2010; Fabian et al., 2011; Ward et al., 2013a]. Clearly, to use discharge as a scaling factor to predict river corridor exchange, a more complete description of the exchange-discharge relationship is required.