Note that some of the information contained in the Appendix of this report may be dated.
Camp Creek, near Prineville, Oregon.
BASEFLOW AUGMENTATION BY STREAMBANK STORAGE
Literature Review and Annotated Bibliography
The term "Baseflow Augmentation by Streambank Storage" is used in this report to refer to the temporary storage of subsurface water in floodplains, streamsides, streambanks and/or streambottom during the wet season, either by natural or artificial means, for later release during the dry season to increase the magnitude and permanence of low flows.
Baseflow augmentation is intrinsically related to the type of streamflow regime, whether ephemeral, intermittent, or perennial, and to the characteristics of the stream-aquifer system, whether effluent or influent. Sustainable amounts of low flow appear to be possible only in streams that can remain effluent throughout the dry season. In order for the stream to remain effluent, the aquifer feeding the stream should be: (1) replenished seasonally with adequate amounts of moisture, (2) shallow enough to be intersected by the stream bottom, and (3) of sufficient size and suitable drainage characteristics.
Adequate aquifer replenishment leads to shallow groundwater tables, which, in aquifers of sufficient size and suitable drainage characteristics, can cause a stream to flow year-round. While aquifer replenishment is generally subject to management, the hydraulic properties of aquifers are largely determined by nature, with little or no human intervention. Therefore, it should be possible to accomplish baseflow augmentation with a management strategy focused on adequate seasonal replenishment of selected aquifers. The aquifer's size and hydraulic properties can be used to identify those which can be readily managed for baseflow augmentation. The vegetative aspects of baseflow augmentation should also be taken into account. Vegetation aids in aquifer replenishment and in raising stream base levels, thereby helping to create an environment conducive to baseflow augmentation.
Four case studies of baseflow augmentation were reviewed for this report: Camp Creek (Oregon), Sheep Creek (Utah), Alkali Creek (Colorado), and Trout Creek (Colorado). These experiences have shown that it is possible to accomplish baseflow augmentation with a broad range of land and water management strategies. At Camp Creek, baseflow augmentation was primarily the result of livestock grazing exclusion. At Sheep Creek, sediment accumulated behind a large barrier dam, and created an artificial aquifer. To this date, this dam and aquifer capture and store water during the high flow season, and release it during the low flow season. The Alkali Creek and Trout Creek watershed rehabilitation projects showed that baseflow augmentation can be counted as the byproduct of structural and nonstructural watershed treatments for the control of gully erosion.
Management strategies for baseflow augmentation fall under one of the following five categories:
This literature review has shown that the physical mechanisms and related processes governing baseflow augmentation by streambank storage are reasonably well understood. Moreover, the limited field experience reviewed for this report has clearly shown the wide-ranging benefits to be derived from a management strategy focused on baseflow augmentation. However, additional research is needed on how to successfully integrate the concept of baseflow augmentation within comprehensive resource management strategies, given the economic, political, and institutional constraints.
ACKNOWLEDGEMENTS The author wishes to thank the following individuals, who reviewed this report in its draft form and made substantial contributions to its content, language, and style.
Leonard F. DeBano USDA Forest Service, Rocky Mountain
Forest and Range Experiment Station,
Robert L. Beschta, Oregon State University, Corvallis, Oregon
Linton Y. Bowie, Pacific Gas and Electric Company
Korbin D. Creek, Pacific Gas and Electric Company
Wayne Elmore, USDI Bureau of Land Management, Prineville, Oregon
Gary Freeman, Pacific Gas and Electric Company
Chuck Harnish, USDA Forest Service, White River National Forest, Glenwood Spring, Colorado
Larry L. Harrison, Pacific Gas and Electric Company
Burchard H. Heede, USDA Forest Service Rocky Mountain Forest and Range Experiment Station, Tempe, Arizona
Donna S. Lindquist, Pacific Gas and Electric Company
George R. McCalla, Pacific Gas and Electric Company
William S. Platts, Don Chapman Consultants, Boise, Idaho
Roland J. Risser, Pacific Gas and Electric Company
Fred D. Stabler, USDI Bureau of Land Management, Rawlins, Wyoming
Bruce Thomas, USDA Forest Service, San Isabel National Forest, Salida, Colorado
Ellen H. Yeoman, Pacific Gas and Electric Company
CONTENTS EXECUTIVE SUMMARY iii
This report contains a literature review and annotated bibliography on the subject of Baseflow Augmentation by Streambank Storage. This refers to the temporary storage of subsurface water in floodplains, streamsides, streambanks and/or streambottom during the wet season, either by natural or artificial means, for later release during the dry season to increase the magnitude and permanence of low flows. The streamflow-regulating mechanism of streambank storage can shave flood peaks and lead to net increases in summer flows. The latter can be used to augment the output of hydropower plants.
The purpose of the report is to review the state of knowledge on the subject. It is expected that the review will serve to identify areas in need of further research, development, and demonstration.
This report is organized into three parts and an Appendix. Part A contains an Analysis and Discussion of the pertinent literature reviewed for this report. Part B contains Annotated Abstracts of references that were deemed to deal directly with the subject under investigation. Part C contains a complete listing of the Bibliography identified in the course of this study, including a bibliography-by-subject section. The appendix contains a list of experts employed by the federal and state governments, universities, and those in private practice, contacted by the principal investigator in the process of producing this report.
Computer searches and other conventional means were used to identify literature sources suitable for inclusion in this report. This effort led to 138 journal papers, research and technical reports, and other published and unpublished articles and reports. References were sought in the following general areas:
1. Baseflow augmentation and/or modification
2. Water yield augmentation by vegetation management
3. Streambank and streambottom storage
4. Instream storage using structures
5. Riparian area water quantity hydrology
6. Riparian area water quality hydrology
7. Riparian area management
8. Streambank surface-subsurface flow analysis and/or measurement
9. Streambank surface-subsurface flow modeling.
All references identified in this study are listed in Part C under the section Bibliography. In addition, the following four specific areas were identified for listing under the heading Bibliography by Subject included in Part C:
1. Baseflow augmentation
2. Streambank storage
3. Riparian area management
4. Surface-subsurface flow analysis.
Thirty-two of the references reviewed for this report were selected for inclusion in Part B: Annotated Abstracts. Papers and reports selected for Part B were deemed to be of sufficient importance to the topic under investigation to warrant abstracting for ready reference. An alphabetic list of abstracts is included in Part B.
This report is submitted in fulfillment of Task 2, Contract No. Z-19-0-893-88, Change Order No. 1, between Pacific Gas and Electric Company and the Trustees of the California State University. The principal investigator is Dr. Victor M. Ponce. Dr. Ponce was assisted by Mr. Jeff Reagan, San Diego State University civil engineering student. Technical managers are Ms. Donna S. Lindquist and Mr. Korbin D. Creek, Pacific Gas and Electric Company, Department of Research and Development, San Ramon, California.