Photo: Bob Bramblett

Building a mechanistic understanding of contaminant transport, transformation, and fate from soils to streams: operationalizing theory with simulation science

Because clean water is a keystone of resilient coupled natural-human systems, understanding how solutes are transported and processed is a critical scientific objective. Water transport is a primary control on water quality as many solutes are transported and thereby redistributed by water. Across spatial scales from soil columns to catchments, water moves via a suite of flowpaths with varying residence times; some water moves "fast" and other water moves "slow." The accumulation of these residence times constrains the biogeochemical potential of a system to transport or process solutes. In the case of nutrients such as nitrate, surface-water concentrations depend on the overall biological processing that occurs in geomorphic process domains (e.g., soil, groundwater, stream). This overall biological processing is, in turn, dependent on solute transport to and biotic demand for a solute in reactive sites. Thus, overall biological processing is constrained by the interplay between rates of reaction and rates of transport, much like a chemical reactor.

I am currently building a simulation model to test the hypothesis that geomorphic process domains function as "ecological bioreactors," starting with streams as an example process domain - but I will ultimately extend this model to groundwater and soils. Two key advantages are emerging as I pursue this approach. One, I can develop predictions of how process domains will respond to (or have responded to) management actions which alter the hydrologic connections with and residence time distributions of reactive zones, e.g., stream restoration or channelization changing hyporheic function. Two, this model enables simulation of the effects of preferential flow and varying residence time distributions in a connected matrix (e.g., soil, cobbles) without physically-based math describing multiple hard-to-measure parameters. This approach opens the door to investigating how variations in uptake kinetics influence the overall biotic uptake of a process domain - stream or other - independent of (or in concert with) changes to the residence time distribution of reactive zones.

Publications: None yet; stay tuned!

Collaborators: Stephanie Ewing, Rob Payn, Maury Valett, Geoff Poole

Funding: Consortium for Research on Environmental Water Systems (CREWS) National Science Foundation EPSCoR Cooperative Agreement #OIA-1757351

Improving hazard preparedness with narrative science messages: an interdisciplinary mixed-methods approach

Conventional risk communication assumes that scientific information alone will lead people to engage in risk reduction behaviors; however, scientific information in isolation rarely affects hazard preparedness. New information about flood hazards is unlikely to avert the hazard-to-disaster trajectories because an alarming gap persists between scientific predictions of hazards and the general population's perceptions of risks associated with those very same hazards. In turn, preparedness decisions are often based on subjective factors derived from life experiences and cultural values rather than up-to-date science information. One way to improve risk communication is to use narrative structure to relay the story of the scientific information.

Our research team has taken an interdisciplinary approach to risk communication in support of hazard perparedness by testing the persuasiveness of narrative messages to communicate scientifically-accurate information of riverine flood risk.  According to the theory described in the Narrative Policy Framework (NPF), people communicate about and understand their world primarily through narratives; as such, narratives are powerful in shaping opinions and decisions. As we demonstrate in our 2019 PLoS One paper, narratives elicit greater affective responses than conventional science messages, affirming a central tenet of NPF theory: the most vital narrative element is that of the character.

Our team is also working at the frontier of interdisciplinary, mixed-methods research to improve the construction of science messages.  Several fields of research depend on message testing to assess how people respond to scientific, social, medical, and political information in messages. Research across these diverse fields has focused extensively on participant responses to messages. However, the paucity of research addressing how to construct message treatments is opaque at best. Our research team argues that the existing "black box" paradigm of message construction threatens scientific integrity in message testing via numerous unmitigated threats to validity and reliability. To address these threats, our research team has developed and implemented an innovative mixed-methods protocol that integrates semi-structured interview data and natural language processing to more precisely develop messages for subsequent testing in focus groups or surveys.

Publications: Shanahan et al. (2019); Bergmann et al. (2020)

Collaborators: Liz Shanahan, Jamie McEvoy, Eric Raile, Clem Izurieta, Henry King, Geoff Poole, Richard Ready, Nicolas Bergmann

Funding: National Science Foundation grant #CMMI-1635885.

The nexus of parsimony and complexity: simulating whole-system biogeochemistry using first principles

Understanding the linkages amongst biogeochemical cycles is a well-recognized, critical scientific objective. However, progress has been hampered by an inability to simulate several elemental cycles contemporaneously. Thus, to assist thinking in terms of biogeochemical systems rather than individual elemental cycles, we developed the "Generalized Algorithm for Nutrient, Growth, Stoichiometric and Thermodynamic Analysis" (GANGSTA) that automates the creation of user defined, constraint-based biogeochemical models with any number of elemental cycles, microbe types, and microbial pathways. Such models are founded in thermodynamic theory and simulate microbial metabolism, growth, and linked elemental cycling in user-specified in silico biogeochemical systems subject to stoichiometric constraints.

In our 2019 paper in Ecological Informatics, we present a series of GANGSTA-derived models that simulate linked carbon, nitrogen, oxygen, and sulfur cycling and reproduce realistic biogeochemical patterns. Among the most important implications of our modelling exercise is a clear demonstration of how ecosystem models that focus only on carbon and nitrogen cannot adequately account for the full energy and chemical budgets of ecosystems.  We hope that the GANGSTA will inspire biogeochemists, systems ecologists, and computational biologists alike because it efficiently instantiates conceptual models via a computational framework, facilitating rapid hypothesis creation, testing, and validation.  We don't yet have GANGSTA up on CRAN, but the 'gangsta' R package can be downloaded from GitHub here.

Publications: Reinhold et al. (2019)

Collaborators: Geoff Poole, Libby Mohr, Clem Izurieta, Ashley Helton, Rob Payn, Emily Bernhardt, Alice Carter

Funding: National Science Foundation grant #DEB-1021001; National Science Foundation EPSCoR Cooperative Agreement #EPS-1101342

Quantifying hydrogeomorphic controls on invasions of Elaeagnus angustifolia (Russian olive) on riverine floodplains

Elaeagnus angustifolia (Russian Olive) invasions threaten native plant communities and are commonplace in many riverine corridors in western North America. Depth to water table, hydrochory, and seed deposition are all potentially important drivers of Russian Olive distributions in floodplains. Each of these mechanisms is governed by fluvial hydrogeomorphology; however, hydrogeomorphic controls on Russian Olive distributions within floodplains are poorly understood.  My colleagues and I are working to determine how Russian Olive invasions are correlated with patterns in flood-inundation frequency and hydrogeomorphic legacy to begin to tease out the potential for hydrochory to accelerate invasion rates and to understand the floodplain habitats most vulnerable to invasion.

Publications: West et al. (2020)

Collaborators: Natalie West, Geoff Poole, John Gaskin, and Erin Espeland

Funding: United States Department of Agriculture Agricultural Research Service and Department of Interior Bureau of Land Management

The importance of side channels--and the fluvial processes that maintain them--for riverine biota

The focus of my Ph.D. research was to understand how alterations to fluvial processes caused by manmade structures (e.g., bank stabilization, rip rap, dikes) influenced fish assemblages and fish habitats in a large, unimpounded alluvial river.  I published three papers summarizing this work, which addressed (1) quantifying the changes in side channel areas over a 50 year period and relating these changes to the density of manmade structures that "plug" side channels; (2) comparing the habitat use of side channels to main channels by small fish during the late-spring/early-summer freshet; and (3) quantifying how bank stabilization and side channels influenced main-channel fish assemblages during base flow.  Since completing my Ph.D., I've continued this vein of research in a collaboration led by Brian Tornabene, focused on understanding the movement and habitat selection patterns for a species of riverine turtle (Apalone spinifera).

Publications: Reinhold et al. (2016); Reinhold et al. (2017); Reinhold et al. (2018); Tornabene et al. (2019)

Collaborators: Al Zale, Bob Bramblett, Geoff Poole, Dave Roberts, Brian Tornabene, Mike Duncan, Matt Jaeger

Funding: United States Army Corps of Engineers; Montana Cooperative Fishery Research Unit

Unscrambling hyporheic and atmospheric drivers of stream water temperatures: a mechanistic approach

In collaboration with Geoff Poole (MSU) and Scott O'Daniel (CTUIR), I am guiding and supporting the efforts of Ph.D. student S. Katie Fogg as she develops a state-of-the art simulation model to describe how the rate of hyporheic exchange and the residence time distribution of water in alluvial aquifers influences stream temperature at both the daily and annual time scales. Katie's simulation approach, which incorporates a residence time distribution within the transient storage zone of rivers, provides a new means of simulating hyporheic influences on river channels using 1D models of stream flow.

I continue to engage with my former postdoctoral adviser, Geoff Poole, and members of the Fluvial Landscape Ecology Lab as we collectively work to quantitatively describe the hydrologic geometry of hyporheic zones in rivers with expansive coarse-grained alluvial aquifers and to scale heterogeneity in riverine transient storage modeling.

Publications: Fogg et al. (2020) 

Collaborators: S. Katie Fogg, Geoff Poole, Scott O'Daniel

Funding: Confederated Tribes of the Umatilla Indian Reservation