Understanding the Hydrogeochemical Response of a Mountainous Watershed Using Integrated Surface‐Subsurface Flow and Reactive Transport Modeling

Abstract

Mountainous watersheds supply a significant portion of the water resources used in regions downstream of these headwater catchments, particularly in arid and semi-arid regions. These watersheds are especially sensitive to the climate changes that are likely to impact the management of water resources. An example is the upper Colorado River watershed, which serves as the primary water source in the western United States (U.S.). However, the western U.S. has been experiencing water scarcity (Garrick et al., 2008), for example, low volumes at Lake Mead, Nevada have triggered for the first time a water shortage declaration (Fountain, 2021). Snow-dominated mountainous watersheds store water in the form of snowpack in the winter and release it by snowmelt in the summer. As a result, global warming could fundamentally alter the rain-snowfall ratio, shift early snowmelt, and

Understanding the hydrological response of a headwater-dominated catchment by analysis of distributed surface–subsurface interactions

“…The saturated permeabilities were set based on the values reported by Tokunaga and collaborators 43 , where permeability values at a hillslope in the region are quantified through field observations. The van Genuchten soil parameters 44 were based on values reported by Xu and collaborators 45 , where a hydro-geochemical model of a neighboring catchment has been calibrated. We summarize permeability and van Genuchten values in Table 1 , where the permeability taken from Tokunaga and collaborators 43 is under the column (P0).…”

Integrating Tide‐Driven Wetland Soil Redox and Biogeochemical Interactions Into a Land Surface Model

“…PFLOTRAN is coupled to ELM via the Alquimia interface (Andre et al, 2013), which is designed as a standardized application programming interface (API) for incorporating existing third-party biogeochemistry codes within environmental transport models. Alquimia has previously been used to connect the Advanced Terrestrial Simulator (ATS) model with PFLOTRAN for watershed-scale reactive transport simulations (Jan et al, 2021;Molins et al, 2022;Xu et al, 2022). Alquimia organizes key chemical information into mobile and immobile (sorbed) concentrations of solutes, as well as volumetric fractions of minerals.…”

Inorganic Hydrogeochemistry in the 21st Century

“…Notably, growing computing power has facilitated the application of coupled reactive transport models (RTMs), in which the transport of species is described by the advection-dispersion equation and the computation of aqueous speciation, mineral dissolution and precipitation, and surface complexation in the multicomponent, multispecies chemical systems at every node and time step (e.g., Steefel et al 2015). Numerous papers have been published on CO 2 storage in aquifers (see review by Dai et al 2020), MAR (e.g., Wallis et al 2011), and watershed hydrogeochemistry (e.g., Xu et al 2022). These studies are a significant step toward integrating fluid flow and chemical reactions and thus have enormous potential to provide useful hydrogeochemical insights.…”