Watershed Restoration
Dams, diversions and other human uses such as grazing and logging have significantly altered the character of most California rivers --- radically changing flow patterns, channel topography, vegetation and habitat for aquatic species. In support of efforts to preserve water quality and riparian habitat, scientists from a variety of disciplines are applying their expertise to advance the fundamental science, tools and techniques of watershed restoration.
- Pulsed Flow Effects on Foothill Yellow-legged Frog
- Evaluation of Bear Creek Meadow Restoration Project
- Spawning Habitat Rehabilitation Project (SHIRA)
Pulsed Flow Effects on Foothill Yellow-legged Frog
Over the last half century, the Foothill Yellow-legged Frog (R. boylii) has declined dramatically, especially in Southern California and the southern Sierra Nevada mountains. Dams and reservoirs have been cited as likely factors in this decline because they drastically alter the flow regime and sediment budget of rivers in which this species has evolved, resulting in permanent alteration to in-stream habitats. The ensuing impact on R. boylii status has been a focus of study over the last decade, but many knowledge gaps remain. Perhaps one of the largest gaps in understanding the effects of dams is determining the role of large aseasonal fluctuations in water discharge, referred to as pulsed flows, in R. boylii decline. In this study conducted jointly with the U.S. Forest Service Sierra Nevada Research Center, pulsed flow effects on R. boylii are examined by combining: (1) analyses of existing empirical data; (2) laboratory and field experiments that quantify the physical tolerances and behavioral responses of tadpoles to changes in velocity; and (3) development of a 2-dimensional (2D) hydrodynamic modeling approach that evaluates the effects of pulsed flows on breeding and rearing habitat.
Publications
- Pulsed Flow Effects on the Foothill Yellow-Legged Frog (Rana boylii): Integration of Empirical, Experimental and Hydrodynamic Modeling Approaches
Jeffrey Mount, Sarah Yarnell, Sarah Kupferberg, and Amy Lind. January 2008. Public Interest Energy Research Program final project report.
Evaluation of Bear Creek Meadow Restoration Project
This project evaluated the restoration of Bear Creek, immediately upstream of the Fall River, in Modoc County, California. Approximately two miles of degraded meadow creek was restored five years ago by a private landowner. This assessment reconstructed changes in the hydrologic balance associated with the restoration and the response of riparian and wetland plant communities to changes in groundwater conditions. Hydraulic modeling was conducted to evaluate and predict the geomorphic response of the designed restoration channel and to identify elements of the design which promote channel stability. This work was conducted by Christopher Hammersmark, a Ph.D. candidate in Hydrologic Sciences.
Publications
- Assessing the Hydroecological Effects of Stream Restoration
Christopher T. Hammersmark. 2008. Dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Hydrologic Sciences.
Spawning Habitat Rehabilitation Project (SHIRA)
Throughout the Northern Hemisphere, rivers that once sustained robust anadromous salmon and trout runs are now regulated and impacted by dams, diversions, channelisation and instream mining. These impacts include loss of the sediment, gravel bars, hydraulic jumps and large woody debris that provide favorable spawning habitat.
The SHIRA project has developed a modeling package to guide the design of spawning gravel restoration projects. Using an interdisciplinary rehabilitation design framework drawing from geomorphology, aquatic biology, civil engineering, and physics, SHIRA allows restoration managers to optimally enhance physical habitat, effectively compare alternate scenarios and identify options least likely to erode. The SHIRA approach is being tested at three demonstration sites: Lower Mokelumne River, Lower Yuba River and the Trinity River.
Reports and publications can be found at: http://shira.lawr.ucdavis.edu/introduction.htm