Seminars are the 4th Tuesday of every month at 12pm CT, unless otherwise specified.
We have a few speakers lined up to give seminars, but it would be great to include other formats such as topical discussions or panel Q&A sessions. If you are interested in giving a seminar, have a topic you'd like to discuss with other USGS geomorphologists, or any other idea for a meeting, contact Jess LeRoy (email@example.com).
Table of Contents
Speaker: Joel Groten
Abstract: Luna Leopold, first chief USGS hydrologist, realized the deficiency in detailed data on hydrologic and geomorphic processes which led him to the idea of establishing an international network of small drainage basins and other selected sites where observations of basic processes would be made over long periods of time. The network of observational sites has been named Vigil, from the Latin vigilia, a watch or surveillance over time and was established in the early 1960s. The Vigil Network was a cooperative international effort to standardize, store, and share data, and it has survived the transition from paper to digital. Recently, this achieved data was a risk of disappearing when the USGS switched to the Drupal web application. Therefore, the USGS underwent an effort to convert Vigil Network files to be compatible with a USGS data release, so they are available to the next generation of scientists. Having the data accessible to the next generation of scientist was a goal of the original scientist who worked to collect and perverse this data. This talk will highlight the history of the Vigil Network and highlight the data available in the USGS data release.
Speakers: Silvia Terziotti and Christy-Ann Archuleta
Abstract: The U.S. Geological Survey maintains the 3D Elevation Program (3DEP) elevation data and the National Hydrography Dataset (NHD) across the United States. Surveys of elevation and hydrography users in the national Hydrography Requirements and Benefits Study (2016) documented a strong need for horizontal and vertical integration of elevation and hydrography data. The USGS published the “Elevation-derived Hydrography Acquisition Specifications and Capture Conditions” document to provide a consistent data structure and set of features for an elevation-derived hydrography (EDH) product for conflation into the NHD. Hydrography developed using these specifications will be horizontally and vertically aligned with the 3DEP high-resolution bare-earth digital elevation model data. Feature density will, at a minimum, match that of the high-resolution NHD.
This presentation will describe the required fields, geometry, alignment and other special considerations to meet the specifications for NHD hydrography derived from high-resolution elevation data, and the geomorphologic derivatives of 3DEP data used to evaluate the horizontal and vertical placement of the features.
Speakers: Adam Benthem
Abstract: USGS’s extensive stream gage network has significantly advanced our hydrologic understanding of watershed dynamics through the calculation of long-term streamflow measurements. These measurements include channel geomorphic properties such as channel area, stage height, bed elevation, and width which the study of is commonly referred to as specific gage analysis. Several recent studies have used this data to assess regional changes in river dynamics in response to climate, land use, and hydraulic changes. However, gage placement on rivers is not random but is preferentially located in stable reaches to facilitate flow measurements. To evaluate if gage-derived geomorphic data is appropriate for broader regional analysis, we compiled river gage channel morphology data for 16 alluvial streams in New England, 11 which have experienced increase flood frequency and magnitude in recent decades and 5 which have remained hydrologically stable. We compared the specific gage analysis results of these sites to aerial image-derived channel area change between pre-1975 and post-1975 data. Our preliminary results indicate that gage-derived geomorphic trends are not consistent with aerial image-derived trends. In locations with increased flood frequency and magnitude, gage data show no net aggradation and erosion for the region. However, aerial image analysis of these same sites shows consistent channel erosion since the 1970’s. The hydrologically stable streams show no change in channel conditions from either gage analysis or in the aerial analysis. We believe this observed discrepancy between gage and aerial data is driven by the lack of dynamic river features, such as meander bends, in-channel deposits, and sidebars, at gage sites. These features are the most sensitive to changes in hydrologic function and sediment supply but are actively avoided during gage placement. As a result, specific gage analysis may be inadequate to quantify small alterations in river function and form and may underrepresent regional changes to river systems.
Speakers: Molly Wood (USGS), Paul Boyd (USACE), and Rose Dopsovic (Bowhead Technical Enterprise Solutions, LLC, Contractor to USACE)
Abstract: Access to bathymetry, sediment, and other geomorphology data for rivers and reservoirs is a critical need in multiple agencies and academia. These data are needed to make water-resource-management decisions regarding river restoration design and monitoring, resource protection, infrastructure design and sustainability, flood-risk reduction, and natural disaster response. Because of renewed interest and technological advances, representatives from multiple federal agencies and academic institutions have created a new working group to scope the development of a Geomorphology Data Exchange Portal to increase access to needed data. A prototype Portal has been developed which shows locations of and provides access to datasets from multiple federal agencies in two pilot watersheds: Delaware River, in the northeast U.S., and Cherry Creek, Colorado.