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S67. Understanding geomorphic processes of the Upper Mississippi River to support natural resource decision-making

The hydrogeomorphology of a coupled river–floodplain system affects the distribution and abundance of riverine habitats. We seek a Mendenhall to synthesize topographic, bathymetric, and land-cover data sets; collect and analyze additional data to understand the changing geomorphology of the Upper Mississippi and Illinois rivers; and evaluate implications of these changes for habitat restoration.

Research Opportunity Description

Geomorphic adjustments through river corridors and drainage basins can take years to millennia to complete and lag their drivers, such as river-control-structure emplacement, land-use change, or precipitation-pattern change. Hence, geomorphic trajectories can be complex and challenging to predict. For the Upper Mississippi and Illinois rivers (hereafter the Upper Mississippi River System, UMRS), ongoing geomorphic changes are fundamentally altering the mosaic of riverine habitats, for example by infilling backwaters and impounded areas, and through channel incision and bank erosion downstream from dams.

Improved understanding of ongoing and future changes in hydrogeomorphology – that is, the integrated effects of changes in hydrology and geomorphology – is needed for effective management and restoration of the UMRS. The primary objective for this project is to improve our understanding of how, where, and to what degree the geomorphology of UMRS is changing and expected to change over decades to centuries. Related supporting questions that may be pursued include:

  1. How do recent and expected future geomorphic changes relate to long-term changes in discharge and extreme weather events?
  2. How are geomorphic changes affected by ongoing navigation channel operations, e.g., lock and dam operations, dredging and dredge spoil placement, wing dikes, closing structures, revetments?
  3. What are the implications for the future spatial and temporal distributions of habitat conditions such as water depth; inundation frequency/depth/duration; water residence time in floodplain water bodies; and physical, biological, and chemical properties of the UMRS?

This research will be conducted as part of the Long Term Resource Monitoring element (LTRM) of the US Army Corps of Engineers’ Upper Mississippi River Restoration Program (UMRR). It will involve collaboration with a diverse group of scientists, natural resource managers and habitat restoration practitioners. We anticipate that the research questions pursued will be co-produced with these program partners. We anticipate that work will incorporate existing data and previous research and strategically collect and analyze additional data. Existing data include: 

  1. Systemic topographic (floodplain elevation) and bathymetric (water depth) GIS data that span most of the Upper Mississippi and Illinois Rivers. This systemic data set is a compilation of airborne LiDAR (collected during 2007 and 2011) and bathymetric survey data collected across an extended time period (approximately 1989–2011). Initial pilot studies are beginning in fiscal year 2024 to refine methods for collecting a second iteration of these topobathymetric data. Work within this research opportunity will inform, and benefit from, the collection of these additional data. 
  2. Land-cover data derived from aerial photography collected at a decadal intervals (1989, 2000, 2010/11, 2020 (processing is ongoing)). A previous assessment of geomorphic change based on the land-cover data (through 2010) identified and quantified newly exposed land across the UMRS (Rogala et al. 2020a; Van Appledorn and Rogala 2022). Additional understanding of geomorphic change in the UMRS may be derived by similar or new analyses that integrate the 2020 and earlier land-cover data.
  3. Multiple data sets derived from bed-elevation sampling along transects in select backwaters of Navigation Pools 4 and 8, from which rates of sediment accumulation and erosion have been estimated (Rogala et al. 2020b, Van Appledorn and Rogala 2022). Initial analyses of these data found a net increase in elevation across all sampled areas indicating sediment accumulation, but substantial variability existed among and within those transects, including multiple areas of net erosion. Further analysis of the existing data, as well as future assessments of the areas represented by these transects, could provide a better understanding of the factors driving the observed spatial variability in sediment accumulation and erosion. 

Previous, related work includes the development of a conceptual model for geomorphic change of the UMRS, creation of initial maps of potential sensitivity to hydrogeomorphic changes for select areas of the UMRS, and the use of hydroacoustics to quantify geomorphic change in side channels. 

Eventually, comparison of the existing and future topobathymetric data could improve our understanding of how the UMRS has changed and our ability to forecast its future changes. However, the timeline for the collection of a second iteration of systemic data is uncertain and may be several years in the future. In the short-term, novel fluvial geomorphic approaches to existing topobathymetric data (both full-coverage and repeat transects), decadal land-cover change data, and predictive modeling may permit general forecasts of the types of areas where more rapid or greater magnitude bathymetric changes are likely to occur. These forecasts could be tested in select areas through collection and analysis of additional bathymetric data. Particularly important is linking field-validated predictions to changes in how habitats of management and conservation interest are distributed. Together, these approaches would yield insights into the changing geomorphology of this large, coupled floodplain–river system.

Interested applicants are strongly encouraged to contact the Research Advisor(s) early in the application process to discuss project ideas.

 

References:

Rogala, J.T., Fitzpatrick, F.A., and Hendrickson, J.S. 2020a. Recent planform changes in the Upper Mississippi River. U.S. Geological Survey, LTRM-2019GC8, 33 p. Available upon request from Jeff Houser (jhouser@usgs.gov). 

Rogala, J.T., Kalas, J., and Burdis, R.M. 2020b. Rates and patterns of net sedimentation from 1997–2017 in backwaters of pools 4 and 8 of the Upper Mississippi River. U.S. Geological Survey, LTRM-2018ST4, 23 p. Available upon request from Jeff Houser (jhouser@usgs.gov). 

Strange, J. and J.T. Rogala. 2021.  Using Hydroacoustics to Determine Geomorphic Changes in Select Side Channels of Upper Mississippi River System Pools. LTRM Completion Report. Available upon request from Jeff Houser, jhouser@usgs.gov

Van Appledorn, M. and J.T. Rogala 2022, Hydrologic indicators, chap. B of Houser, J.N., ed., Ecological status and trends of the Upper Mississippi and Illinois Rivers. U.S. Geological Survey Open-File Report 2022-1039, https://doi.org/10.3133/ofr20221039.

 

Proposed Duty Station(s)

La Crosse, Wisconsin

 

Areas of PhD

Fluvial geomorphology or related fields (candidates holding a Ph.D. in other disciplines, but with extensive knowledge and skills relevant to the Research Opportunity may be considered).

 

Qualifications

Applicants must meet one of the following qualifications:  Research Geologist or Research Hydrologist.

(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.)

 

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