44. Simulating Interactive Responses of Stream Flow and Temperature Distributions to Climate Change at the Watershed Scale

Research under this postdoctoral position will augment and synthesize current research on stream-temperature modeling being conducted in the U.S. Geological Survey (USGS) within the scope and scale of watershed modeling. The research will be used to enhance our deterministic, distributed-parameter, physical-process rainfall-runoff model, the Precipitation Runoff Modeling System (PRMS) through the development of a stream-temperature model component. Integrated hydrologic flow and stream temperature modeling will increase our understanding of the interactions of climate, land use, and land cover dynamics that influence the structure and function of the watershed and stream ecosystem.

Stream temperature is a primary driver of stream ecosystem structure and function, and is a vector of lotic ecosystem sensitivity to climate change.  Adding a stream temperature component to the PRMS will allow us to build on our research efforts to simulate land-use and climate change. Additionally, the research is intended to be integrated with the USGS Ground-water and Surface-water Flow (GSFLOW) model, an integration of the PRMS and the USGS Modular Ground-water Flow model (MODFLOW). The USGS is currently considering how to use the transport mechanism in MODFLOW for water-temperature modeling. A dynamic and distributed ground-water and surface-water (GW/SW) model, integrated with water temperature, will provide more complete and accurate assessments of future water availability to stream ecosystems.  

We seek an innovative postdoctoral scientist with the ability to address this complex integrative research and development. The scientist would be expected to work collaboratively with the USGS on this topic. Specifically, the Mendenhall Fellow will be expected to explore:

• existing stream temperature models and determine the methodology appropriate for integration with PRMS and GSFLOW
• integration of this methodology with the transport mechanism in MODLFOW.

Upon completion of the integration, the Fellow is expected to explore one or more of the following research applications:

• influence of climate dynamics on long-term, stream temperature trends
• identification of flow paths and components of flow through the coupled GW/SW watershed system.
• influence of stream temperature on fish population dynamics
• effects of evolving landscapes and land-use changes on stream temperature

Current studies by the Research Advisors expected to benefit from a stream temperature simulation component include:

Water availability for ecological needs: Research in the Flint River basin is focused on the use of distributed watershed models to predict flow statistics significant to ecosystem structure and function. Spatial patterns are being synthesized from remotely sensed data sources and subsequently used to drive dynamic model inputs. Dynamic modeling allows us to address the influence of changing land use and land cover on stream ecosystems. To adequately evaluate current and future water availability, evolution of the landscape must be considered in conjunction with dynamics of the climate.

Integrated watershed-scale response to global change in selected basin across the United States: Current general circulation model simulations of future climate through 2099 project a wide range of possible scenarios. To determine the sensitivity and potential impact of long-term climate change on the freshwater resources of the United States, 17 basins from different hydroclimatic regions have been selected as study sites. Selected GCM climate change scenarios will be used as drivers to evaluate regional hydrologic responses using the PRMS and GSFLOW models.

Impact of past and future stream temperature and flow changes on endangered Atlantic salmon population persistence: Current research in northeastern coastal rivers is investigating changes in the contribution of groundwater discharge (baseflow) to total streamflow during periods of low flow in the Northeast and the potential impact of changes in baseflow and in stream temperatures on Atlantic salmon population persistence. This work will (1) assess historical regional trends in baseflow, (2) complete development of an Atlantic salmon population-survival model, (3) calibrate watershed models of coastal Atlantic-salmon basins in the region and derive future flow and stream-temperature scenarios using GCM climate change scenario data, and (4) use watershed model output as input to the salmon-survival model to estimate Atlantic salmon population persistence due to climate change.

Proposed Duty Station: Denver, CO

Areas of Ph.D.: Hydrology, hydraulics, geochemistry, biogeochemistry, geology, limnology

Qualifications: Applicants must meet one of the following qualifications: Research Hydrologist, Soil Scientist, Research Chemist, Research Geologist

(This type of research is performed by those who have backgrounds for the occupations stated above. However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the Human Resources specialist.)

Research Advisor(s): Lauren Hay, (303) 236-7279, lhay@usgs.gov; Steve Regan, (303) 236-5008, rsregan@usgs.gov

Human Resources Office contact: Vanessa Chambless, (303) 236-9584, vchambless@usgs.gov

Summary of Opportunities