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Mapping and modeling variable headwater streams: ongoing syntheses
Citation:
Christensen, J., H. Golden, C. Lane, D. Mahoney, K. Jaeger, AND R. Sando. Mapping and modeling variable headwater streams: ongoing syntheses. 2023 American Geophysical Union Fall Meeting, San Francisco, CA, December 11 - 15, 2023.
Impact/Purpose:
Headwater streams are important to ecosystem health, are challenging to characterize, and regulatory policies vary in their protection of these systems. We present a synthesis resulting from two reviews. One review is of the current state of mapping these variable systems and emerging approaches to improve that mappings. The second review is approaches to modeling headwater dynamics. A better understanding of both the spatial and temporal dynamics of headwaters is important to defining their role in healthy watersheds and how such characterizations might inform regulatory policies.
Description:
The size, abundance, and hydrological variability of headwater streams make mapping their extent and characterizing their temporal dynamics challenging. Yet this information is critical for understanding and managing the ecosystem functions these vulnerable systems provide. Water managers, planners, scientists, and the public-at-large need reliable data on headwater streams as they make water-resource decisions across local-to-national extents. Here we present two approaches aimed at improving headwater stream data. First, we discuss the status and future directions of CONUS-scale geospatial datasets of streams and identify emerging technologies for narrowing information gaps. We demonstrate how remotely sensed imagery can broadly characterize surface-water extent and dynamics while noting that it currently lacks fine temporal and spatial resolutions for many headwaters. Evolving field-based technologies can improve our understanding of headwater stream dynamics but require significant resources to move beyond the current level of limited spatial and temporal extents. Second, as hydrological modeling helps to bridge these spatial and temporal gaps, we highlight a variety of catchment-scale modeling efforts focused on variable stream extent and connectivity. We discuss an ongoing synthesis of headwater streamflow modeling, asking questions such as: “What processes and dynamics are well represented in models?”; ”What spatial and temporal scales are considered?”; “Where do we have gaps in our modeled representations of headwaters?”; and, “How can we use and combine models to improve modeling outputs?”. These syntheses will help enhance the mapping and modeling of headwater streams and inform water-resources research and policy decisions.