Critical Zone Observatory Projects

Critical Zone Hydrology

Project Title:

Reynolds Creek Carbon Critical Zone Observatory

Project Overview:

The Reynolds Creek Critical Zone Observatory (RC CZO) is being established to address the grand challenge of improving prediction of soil carbon storage and the processes governing its fate at the plot to the landscape scale. The RC CZO will be co-located with the Reynolds Creek Experimental Watershed (RCEW) in southwest Idaho, which has been administered by the United State Department of Agriculture -Agricultural Research Service (USDA-ARS) for over 50 years. The RCEW is particularly well suited for the CZO because of its strong gradients in climate, vegetation, and distributions of soil organic and inorganic carbon. The observatory will leverage existing scientific infrastructure that includes long-term, spatially extensive meteorological and soil monitoring.

This project fits into the CZO-Hydrology research themes.

Funding:

Funding for this project is provided by NSF, EAR Division Of Earth Sciences

Key Collaborators:

• Kathleen Lohse (Idaho State University, Principal Investigator)
• Nancy Glenn (Boise State University, Co-Principal Investigator)
• Shawn Benner (Boise State University, Co-Principal Investigator)
• Mark Seyfried (US Department of Agriculture,  Agricultural Research Services, Co-Principal Investigator)

Lab Participants:

• Alejandro Flores (Co-Principal Investigator)
• Chao Chen (Post-doc)

Needs:

1. Affected by various factors of climate, vegetation, geology, chemistry, geophysics, biology, etc., each basin is formed in its own unique way.  Such uniqueness is not only its structural geomorphology, but also in its hydrologic properties. Understanding the connections between basin form and emergent hydrologic properties is important in many cross-disciplinary problems, from soil moisture assessment to ecological system evaluation.
2. How this basin formation control the emergent hydrologic properties and what corresponding patterns and features we would expect/conclude from their relationship. Specifically, leveraging the importance of critical zone as a bridging role between the geomorphologic structure and hydrologic features in hydro-geophysical research, we focus on the CZ as a breaking point to look at the questions we have.

Hypothesis:

• With increased saprolite thickness, the streamflow shows different temporal patterns, such as streamflow curve shape and peak timing
•  Landscape controls the non-linearity between the distributed soil-water holding capacity and the emergent hydrologic properties to storm events (P/soil storage).
• The higher variability of soil thickness (TMR) the slower subsurface saturation develops.

Tools, models, datasets:

• This research/projects employs the ParFlow, which is parallel-run integrated hydrologic model. It uses 3-D Richards equation to solve the heterogeneous subsurface flow, and it couples with CLM model to simulate the dynamic water interaction between surface hydrology and subsurface hydrology.
• Landlab is a python package, used to model earth surface processes. In this research, it is used to develop watersheds with different topography determined by two erosion mechanisms: fluvial-erosion dominated and diffusive-erosion dominated watershed.

Expected outcomes and deliverables:

Potential outcomes from this research/project include:

• Code for Landlab scripts of developing two synthetic watersheds
• Parflow models with varied saprolite thickness
• Parflow-CLM models with 7-day storm event

Key words:

integrated hydrologic modeling, CZO, hydrogeomorphology, Parflow

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Subsurface Biogeochemical Research

Project Title:

Model-Data Fusion to Examine Multiscale Dynamical Controls on Snow Cover and Critical Zone Moisture Inputs

Project Overview:

The overall goal of this project is to deepen our understanding of how water is delivered from the atmosphere to mountain watersheds, and the various biophysical factors that control the rate and timing of water delivery to the critical zone.

Funding for this project is provided by the Department of Energy Office of Biogeochemical and Environmental Research, through the Subsurface Biogeochemical Research Program.

Key collaborators

• Dr. Rosemary Carroll (Desert Research Institute)
• Dr. Haruku Wainwright (Lawrence Berkeley National Laboratory)

Lab participants

• Dr. Lejo Flores (PI)
• Dr. Caroline Nash
• William Rudisill
• Allison Vincent.

Needs:

• There is an ongoing need to improve our ability to estimate snow water storage in mountainous headwater environments for both operational forecasting and addressing fundamental scientific questions

1. Exploring new applications for tools like WRF and STARFM in the context of watershed hydrology
2. Leveraging high-resolution datasets to understand full suite of hydrologic process domains in watersheds that may be underrepresented by existing instrumentation

• Snow is assumed to be the dominant source of water for mountainous critical zones, but it is not yet clear how rapidly water is delivered, when, and how it might change as environmental conditions do, as well. It is necessary that we constrain these processes to understand current patterns of delivery, and how delivery might be affected by changing patterns of precipitation.
• There are implications of changing patterns of water delivery on biogeochemical processes modulated by incoming water (e.g. soil carbon storage and release)

Hypothesis/Research Questions/Objectives:

• Interannual variability in the fraction of precipitation arriving in the liquid phase is maximized at elevations that approximately demarcate a transition from shrub-dominated to tree-dominated ecosystems in the East River, Colorado. 
• Within elevation bands corresponding to isohyets in the East River, there are significant associations between topographic factors (e.g. aspect, solar radiation) average and variance in annual number of snow-covered days, and plant functional type
• Average annual time lag between median cumulative annual precipitation and soil water input (the sum of liquid precipitation and melt flux) is positively correlated with elevation, but the interannual variation in the time lag is negatively correlated with elevation.

Tools, models and datasets

This research/projects employs:

• The Weather Research and Forecasting Model (WRF) to produce high resolution (<1 km, hourly) reconstruction of historical climate in the East River over the past 30 years, and
• The Spatial and Temporal Adaptive Reflectance Fusion Model (STARFM) to synthesize Landsat and MODIS datasets into a high resolution (30 m, daily) reconstruction of snow covered area in the East River over the past 20 years.

Expected outcomes and deliverables:

Potential outcomes from this research/project include:

• a 30-year historical reconstruction of climate in Colorado,
• a 20-year historical reconstruction of snow-covered area in the East River Watershed, CO;
• Code to operationalize STARFM for describing snow-covered area in mountainous watersheds

Key words:

critical zone, snow, land-atmosphere interactions, mountain groundwater

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Signals in the Soil

Project Title:

RAISE-SitS Designing models to forecast how biogeochemical fluctuations in soil systems govern soil development, terrestrial water storage and ecosystem nutrient fluxes

Project overview:

The overall goal of this project is to advance our understanding of nonlinear linkages between climate and the soil properties that underpin ecosystem and critical zone services by developing a multi-scale modelling framework to better predict soil biogeochemical systems.

Funding

Funding for this project is provided by the National Science Foundation Award #1841614,

Key collaborators

• Dr. Pamela Sullivan (University of Kansas)
• Dr. Sharon A Billings (University of Kansas, Kansas Biological Survey)
• Dr. Daniel R Hirmas (University of California, Riverside)
• Dr. Li Li (Pennsylvania State University)
• Dr. Hang Wen (Pennsylvania State University)

Lab participants

• Dr. Lejo Flores (Co-PI)
• Dr. Caroline Nash

Needs:

1. There is a fundamental information gap around how soils are responding to changing environmental conditions (land cover, precipitation, temperature, etc.) and the mechanisms driving that change. Empirical evidence suggests that these changes are significant at the pedon-scale and happening rapidly (<3 years) in response to biotic factors.
2. Evidence of changing soil structure – macroporosity, in particular – raises questions about the implications of these changes for the movement and storage of water and biogeochemical weathering products at a continental scale.
3. Land models all currently represent soils as static parameters, despite emerging evidence that they respond dynamically to changes in climate and land use. Developing a means to incorporate dynamic soils into these models will allow us to explore their potential role as a feedback in larger scale, longer term climate predictions.

Hypothesis/Research Questions/Objectives:

• Observed decreases in soil macroporosity under enhanced precipitation result from two mechanisms: macropore “collapse” that corresponds to a decline in soil aggregate stability (primary mechanism) and macropore “clogging” via root growth (secondary mechanism) – Led by Dr. Daniel Hirmas
• Reductions in macroporosity and enhanced root growth and heterotrophic microbial activity with increasing precipitation create a cascading impact on soil chemistry by increasing the frequency of low O2 and high CO2 soil conditions via greater CO2 production and O2 consumption and slower gaseous diffusion ,modifying the relative dominance of active microbial communities responsible for weathering-inducing reactions, particularly at depth.  – Led by Dr. Li Li and Dr. Sharon Billings

• Topography and subsurface layering (e.g. characteristics of soil horizons and the soil-rock interface) can amplify the hydrologic and biogeochemical effects of precipitation-induced soil hydraulic properties at the watershed scale – Led by Dr. Pamela Sullivan, Dr. Sharon Billings and Dr. Hang Wen

• At continental scales, the inclusion of precipitation-induced changes to soil macroporosity will amplify the impact of climate change on hydrology and chemical weathering fluxes relative to “climate agnostic” soil properties – Led by Dr. Lejo Flores and Dr. Caroline Nash

Methods and data used:

Our lab’s component of this project employs:

• The Community Land Model 5.0 (CLM 5.0 C-N) to run a series of factorial-style numerical experiments at a continental scale under a variety of climate scenarios for the years 1980 – 2100.
• Biosphere-Weathering at the Catchment Scale (B-WITCH) geochemical model to examine the impacts of changing soil moisture dynamics on biogeochemical fluxes in a suite of watersheds selected across a precipitation gradient.
• ESRI Story Maps as an education and outreach tool, through the Research Experience for Undergraduates (REU) program

Expected outcomes and deliverables:

Potential outcomes from our lab’s component of this research/project include:

• A suite of parameterizations for climate-responsive pedotransfer functions in CLM 5.0
• A book chapter for Biogeochemistry of the Critical Zone
• A Story Map describing the importance of soils, the effects of climate on soil structure, and the implications of changing soil structure on the many uses of soils across the continental United States.

Key words:

critical zone, land-atmosphere modelling, soil structure, biogeochemical cycles

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