Overview: Sedimentation rates in reservoirs have long been and continue to be of interest to the Subcommittee on Sedimentation (SOS) member agencies, as well as others. Much of the original impetus for conducting surveys to calculate sedimentation rates in reservoirs was to gain a better understanding of the role(s) of reservoirs on watershed sediment-transport processes, so that systems of watershed structures could be designed efficiently to provide floodwater retention and other uses of the stored water. Our understanding of how sediment moves, is deposited, and is subject to erosion and subsequent transport as a consequence of dam removal, rehabilitations, or changed operations will also be enhanced, as additional survey information complements this historical record. Other reasons for quantifying reservoir-sedimentation rates include:
- calculating changes in reservoir storage capacity, thus estimating the useful lifespan of reservoirs,
- designing reservoir sediment-storage allocations,
- managing sediment deposits,
- rehabilitating aging or damaged structures,
- designing sediment-sluicing and other sediment-management structures,
- estimating the mass of captured constituents associated with sediments, such as carbon, and selected water-quality constituents, and
- assessing resource conditions related to land cover, land use, and rates of erosion and sediment production.
Early History of the Effort Culminating in RESSED: The SOS coordinated the collection of reservoir sedimentation-survey data and disseminated survey data sheets (SCS Form 34) to its members since 1953 (Sedimentation Bulletin Number 5, August, 1953: Summary of Reservoir Sedimentation Surveys for the United States through 1950, with 461 survey summaries included). Additionally, the SOS published 5-year summaries of reservoir sedimentation rates in USDA Miscellaneous Publication No. 1362. The survey data sheets were designed to contain all salient information related to the survey of sediment deposits in reservoirs, while minimizing the paper required to capture the information.
Instructions for completing the reservoir-sediment data forms were issued by the SOS, including explanations for the information required in each block or data field. Sedimentation geologists with the Soil Conservation Service (SCS) used a compilation of the completed Form 34 data sheets to calculate regional rates of sediment production from watersheds, sediment deposition in reservoirs, sediment delivery ratios (ratio of erosion to sediment yield), sediment trapping effects of reservoirs (both dry and wet), and the effects of conservation treatment on erosion rates and sediment yield. Latter uses of the data include evaluations of the effect of reservoirs on the global carbon budget, and incorporation into SPARROW models of sediment transport.
The Form 34 data sheets were collected through the SOS through the mid-1980s, and additional Form 34 data sheets were collected independently since then to provide more information to the updated Reservoir Information System (RESIS-II) database. Beginning in the 1990s, use of single- and multiple-frequencies radar, Global Positioning System technology, and digital-data recording and analysis proliferated.
Available reservoir sedimentation-survey data through 1993 have been incorporated into the static RESIS-II database, which is available for downloading.
The RESIS-II database is the foundation for the RESSED database. There are no plans to update the RESIS-II database. RESSED, however, includes additional survey information and will continue to be revised as historical, recently collected, and newly collected survey data are received and pass quality-control checks.
Latter History of the Effort Culminating in RESSED: In the 1980s, the SCS attempted to develop an electronic database for analysis of the survey data. Dennis Erinakes (SCS) supervised the key punching of all of the data on the available, completed Form 34 survey sheets. Attempts to analyze the data using a database-management system (DBMS) at the time were unsuccessful and were abandoned, primarily due to the inadequacy of the DBMS software available at the time.
In 1994, Dr. Jay Atwood of the Natural Resources Conservation Service (NRCS; before Oct. 20, 1994, the SCS) obtained the SCS-produced digital data through Jerry Bernard (NRCS), created a relational database using the Prelude and Informix DBMSs, and performed queries and analyses for the Third Resource Conservation Act (RCAIII). Jerry Bernard was leading an analysis of the status and trends of sedimentation as one subtopic of the studies meeting the Congressional requirements of this Act. Lyle Steffen (NRCS) assisted Dr. Atwood with the technical definitions and information in the database during the conversion and during later analyses and queries. The database was called RSED at the time but quickly became known as RESIS. Subsequent to the completion of the RCAIII reports, the database was offered to the SOS for posting. Lyle Steffen worked with Dr. Atwood to prepare individual state summaries of the information in RESIS. Hard copies of these summaries were provided to each NRCS State office following the RCAIII effort. Lyle Steffen worked with the Information Technology staff at the NRCS National Soil Survey Center to maintain the only working copy of the database following the RCAIII research effort.
Lyle Steffen provided a copy of the RESIS database to the EROS Data Center. Subsequently, Dr. Robert R. Stallard and David Mixon (Stallard et al., 2001) of the U.S. Geological Survey (USGS) utilized the USGS EROS Data Center’s copy of the RESIS database to assist in an evaluation of sediment and carbon storage within the Mississippi River Basin. As part of this effort, RESIS was transferred to a desktop computer environment using the database management programs Paradox and MS-Access. In addition to using the original version of the RESIS data as the core of the new database, referred to as RESIS-II, links were made to:
- the National Inventory of Dams (NID),
- scanned versions of the original primary datasheets, and
- a GIS polygon coverage of boundaries for the reservoir’s watershed.
Drs. Katherine V. Ackerman and Eric T. Sundquist, USGS, subsequently obtained RESIS-II from Robert Stallard and David Mixon with the primary intent to estimate rates and amounts of carbon storage in U.S. reservoirs. In concert with David W. Stewart and Dr. Gregory E. Schwarz (USGS), they improved georeferencing for 1,506 reservoirs, performed other upgrades, and documented the RESIS-II database (Ackerman et al. 2009). It is this version of the RESIS-II database that was updated with new reservoir survey information and named RESSED.
A hopefully complete list of those who have directed substantial time and effort in the over half-century effort to compile and display sedimentation-rate information in U.S. reservoirs appears in the “Acknowledgements” section of this website.