Geology topics
Waite R. Osterkamp
Publications and source records attributed to Waite R. Osterkamp.
Fluvial processes and vegetation - Glimpses of the past, the present, and perhaps the future.
"Most research before 1960 into interactions among fluvial processes, resulting landforms, and vegetation was descriptive. Since then, however, research has become more detailed and quantitative permitting numerical modeling and applications including agricultural-erosion abatement and rehabilitation of altered bottomlands. Although progress was largely observational, the empiricism increasingly yielded to objective recognition of how vegetation interacts with and influences geomorphic process. A review of advances relating fluvial processes and vegetation during the last 50 years centers on hydrologic reconstructions from tree rings, plant indicators of flow- and flood-frequency parameters, hydrologic controls on plant species, regulation of sediment movement by vegetation, vegetative controls on mass movement, and relations between plant cover and sediment movement. Extension of present studies of vegetation as a regulator of bottomland hydrologic and geomorphic processes may become markedly more sophisticated and widespread than at present. Research emphases that are likely to continue include vegetative considerations for erosion modeling, response of riparian-zone forests to disturbance such as dams and water diversion, the effect of vegetation on channel and bottomland dynamics, and rehabilitation of stream corridors. Research topics that presently are receiving attention are the effect of woody vegetation on the roughness of stream corridors and, hence, processes of flood conveyance and flood-plain sedimentation, the development of a theoretical basis for rehabilitation projects as opposed to fully empirical approaches, the effect of invasive plant species on the dynamics of bottomland vegetation, the quantification of below-surface biomass and related soil-stability factors for use in erosion prediction models, and the effect of impoundments on downstream narrowing of channels and accompanying encroachment of vegetation. Bottomland vegetation partially controls and is controlled by fluvial-geomorphic processes. The purposes of this paper are to identify and review investigations that have related vegetation to bottomland features and processes, to distinguish the present status of these investigations, and to anticipate future research into how hydrologic and fluvial-geomorphic processes of bottomlands interact with vegetation."
Characteristics of debris flows of noneruptive origin on Mount Shasta, northern California
Studies of Mount Shasta indicate that eruptive activity has occurred, on the average, once every 800 years. Debris flows and deposits of non- eruptive origin, in addition to those associated with eruptive activity (lava flows, pyroclastic flows, and ash fall), inundate the fans and channels and can endanger people or property on the flanks of the mountain. This study evaluates the source and characteristics of historical noneruptive debris flows in the vicinity of Mount Shasta. At least 70 debris flows of noneruptive origin that occurred during the last 1,000 years have been identified in various stream channels on Mount Shasta. Of the four areas around the mountain, the most active are the McCloud River and The Whaleback-Ash Creek Butte depression; the Sacramento River area is the least active. Between 1900 and 1985, 37 debris flows occurred on different streams, with an average interval of 2.3 years between flows. Since 1900, Mud Creek (nine flows) and Whitney Creek (six flows) have been the most active channels. The path followed by a debris flow is not always at the lowest point in the channel, and the extent of downstream movement depends on the size of the flow. Former channels are inundated by the new flows and deposits, and new channels are eroded. In time, most of the entire channel between valley walls is subject to reworking. Most debris-flow deposits ranged in thickness from 0.4 to 2.5 meters. Thickness tends to decrease in a downstream direction. The deposits are generally of a convex shape, highest in the middle and lowest near the original valley wall. The ratio of water to solids in the slurry- sediment mixture of debris flows averages 68 percent by volume.