Elk-Effects Vegetation Monitoring Program for Tomales Point Elk Range, Point Reyes National Seashore, California
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Flood information is reported for 338 miles of the main stem and six tributaries of the Wapsipinicon River. The information will be of use to those concerned with the design of bridges and other structures and the conduct of various operations on the flood plains of the streams. Included in the report are flood-peak records, gaging-station records, frequency curves, and water-surface profiles. Outstanding floods resulting from extremely heavy rainfall occurred in the upper basin in 1968 and 1969. Those in 1968 produced the highest flood of record at the gaging station at Independence. The flood of 26,800 cfs (cubic feet per second) at this station was the greatest in the period 1933-70. A number of the smaller tributaries experienced floods more than five times the computed 50-year flood. The flood experience on the main stem downstream from Anamosa has not been outstanding. No flood of record has exceeded the 50-year flood in this reach. Flood-profile sheets show profiles of actual flood occurrences and computed profiles of the 25- and 50-year floods at most locations. These sheets also contain tabulations of the flood discharges profiled. A low-water profile and tabulated discharge indicate the range in elevation and discharge along the streams.
Large-scale patterns in fish assemblage structure and functional groups are influenced by alterations in streamflow regime. In this study, we defined an objective threshold for alteration for Oklahoma streams using a combination of the expected range of 27 flow indices and a discriminant analysis to predict flow regime group. We found that fish functional groups in reference flow conditions had species that were more intolerant to flow alterations and preferences for stream habitat and faster flowing water. In contrast, altered sites had more tolerant species that preferred lentic habitat and slower water velocity. Ordination graphs of the presence and functional groups of species revealed an underlying geographical pattern roughly conforming to ecoregions, although there was separation between reference and altered sites within the larger geographical framework. Additionally, we found that reservoir construction and operation significantly altered fish assemblages in two different systems, Bird Creek in central Oklahoma and the Kiamichi River in southeastern Oklahoma. The Bird Creek flow regime shifted from a historically intermittent stream to one with stable perennial flows, and changes in fish assemblage structure covaried with changes in all five components of the flow regime. In contrast, the Kiamichi River flow regime did not change significantly for most flow components despite shifts in fish assemblage structure; however, most of the species associated with shifts in assemblage structure in the Kiamichi River system were characteristic of lentic environments and were likely related more to proximity of reservoirs in the drainage system than changes in flow. The spatial patterns in fish assemblage response to flow alteration, combined with different temporal responses of hydrology and fish assemblage structure at sites downstream of reservoirs, indicate that interactions between flow regime and aquatic biota vary depending on ecological setting. This supports the notion that regional variation in natural flow regimes could affect the development of flow recommendations.
Several important aspects of sediment transport have been investigated by utilizing data from the turbulence flume in the Middle Loup River at Dunning, Nebr. These data have also been used to evaluate sedimentation formulas. However, additional work of a research nature is needed to provide information on specific transport phenomena and on field procedures. On August 26, 1955, representatives of the U.S. Bureau of Reclamation and U.S. Geological Survey met in Denver, Colo., to discuss these needs and the sediment investigations to be made at the Middle Loup River at Dunning, Nebr., during 1956.