Geology topics

Research about Redwood Creek

Source-linked reports with geographic coverage including Redwood Creek.

6 recordsLinked to original sources

USGS2023

A life cycle model for evaluating estuary residency and restoration potential in Chinook salmon

Understanding the spatial and temporal habitat use of a population is a necessary step for recovery planning. For Chinook salmon ( Oncorhynchus tshawytscha ), variation in their migration and habitat use complicate predicting how restoring habitats could impact total recruitment. To evaluate how juvenile life history variation affects a population’s response to potential restoration, we developed a stage-structured model for a Chinook salmon population in a northern California river with a seasonally closed estuary. We modeled the timing of juvenile migration and estuarine use as a function of freshwater conditions and fish abundance. We used the model to evaluate the sensitivity of the population to different estuary and freshwater restoration scenarios that could affect population parameters at different life stages. The population’s run size increased most in response to freshwater restoration that enhanced spawning productivity (egg and fry survival), followed by spawner capacity. In contrast, estuary restoration scenarios affected only a subset of Chinook salmon (average 15%), and as a result, did not have a large impact on the total recruitment of a cohort. Under current condition, estuary rearing fish were over six times less likely to survive than fish that migrate to the ocean in the spring or early summer before estuary closure. Because estuary residents experienced low survival in the estuary and in the ocean, improvements to both estuary survival and growth would be needed to increase their total survival. When life cycle monitoring data is available, life cycle models such as ours generate predictions at scales relevant to conservation and are an advantageous approach to managing and conserving anadromous salmon that use multiple habitats throughout their life cycle.

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USGS2021

Reduced recruitment of Chinook salmon in a leveed bar-built estuary

Estuaries are commonly touted as nurseries for salmonids, providing numerous advantages for smolts prior to ocean entry. In bar-built estuaries, sandbars form at the mouth of rivers during periods of low stream flow, closing access to the ocean and preventing outmigration. We evaluated how summer residency in a leveed bar-built estuary affects the growth, survival, and recruitment of a Chinook salmon ( Oncorhynchus tshawytscha ) population. We performed a mark–recapture study on outmigrants to determine juvenile estuary abundance, growth, and survival. We used returning adult scales and otoliths to determine the relative proportion of summer estuary residents in spawning adults. Juveniles in the estuary grew less after mouth closure, and ultimately summer estuary residents had lower smolt-to-adult survival and contributed disproportionately less to the spawning population than juveniles that reared in the ocean their first summer. Mouth closure may lower food availability and deteriorate estuary conditions by reducing marine prey influx and estuary circulation. This research demonstrates the complexity of estuary dynamics and function as salmonid nurseries, particularly when considering the extensive modification of estuaries.

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USGS2010

Stochastic model for the long-term transport of stored sediment in a river channel

We develop a stochastic model for the transport of stored sediment down a river channel. The model is based on probabilities of transition of particles among four different sediment storage reservoirs, called active (often mobilized), semiactive, inactive, and stable (hardly ever mobilized). The probabilities are derived from computed sediment residence times. Two aspects of sediment storage are investigated: flushing times of sediment out of a storage reservoir and changes in the quantity of sediment stored in different reservoirs due to seasonal sediment transport into, and out of, a reach. We apply the model to Redwood Creek, a gravel bed river in northern California. Although the Redwood Creek data set is incomplete, the application serves as an example of the sorts of analyses that can be done with the method. The application also provides insights into the sediment storage process. Sediment flushing times are highly dependent on the degree of interaction of the stable reservoir with the more mobile sediment reservoirs. The most infrequent and highest intensity storm events, which mobilize the stable reservoir, are responsible for the long-term shifts in sediment storage. Turnover times of channel sediment in all but the stable reservoir are on the order of 750 years, suggesting this is all the time needed for thorough interchange between these sediment compartments and cycling of most sediment particles from the initial reservoir to the ocean. Finally, the Markov model has adequately characterized sediment storage changes in Redwood Creek for 1947–1982, especially for the active reservoir. The model replicates field observation of the passage of a slug of sediment through the active reservoir of the middle reach of Redwood Creek in the 18 years following a major storm in 1964 that introduced large quantities of landslide debris to the channel.

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USGS1996

Channel response to sediment wave propagation and movement, Redwood Creek, California, USA

Redwood Creek, north coastal California, USA, has experienced dramatic changes in channel configuration since the 1950s. A series of large floods (in 1955, 1964, 1972 and 1975) combined with the advent of widespread commercial timber harvest and road building resulted in extensive erosion in the basin and contributed high sediment loads to Redwood Creek. Since 1975, no peak flows have exceeded a 5 year recurrence interval. Twenty years of cross-sectional survey data document the downstream movement of a ‘sediment wave’ in the lower 26 km of this gravel-bedded river at a rate of 800 to 1600 m a −1 during this period of moderately low flows. Higher transit rates are associated with reaches of higher unit stream power. The wave was initially deposited at a site with an abrupt decrease in channel gradient and increase in channel width. The amplitude of the wave has attenuated more than 1 m as it moved downstream, and the duration of the wave increased from eight years upstream to more than 20 years downstream. Channel aggradation and subsequent degradation have been accommodated across the entire channel bed. Channel width has not decreased significantly after initial channel widening from large (>25 year recurrence interval) floods. Three sets of longitudinal surveys of the streambed showed the highest increase in pool depths and frequency in a degrading reach, but even the aggrading reach exhibited some pool development through time. The aggraded channel bed switched from functioning as a sediment sink to a significant sediment source as the channel adjusted to high sediment loads. From 1980 to 1990, sediment eroded from temporary channel storage represented about 25 per cent of the total sediment load and 95 per cent of the bedload exported from the basin.

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USGS1978

Mass movement and storms in the drainage basin of Redwood Creek, Humboldt County, California — A progress report

Numerous active landslides are clearly significant contributors to high sediment loads in the Redwood Creek basin. Field and aerial-photograph inspections indicate that large mass-movement features, such as earthflows and massive streamside debris slides, occur primarily in terrain underlain by unmetamorphosed or slightly metamorphosed sedimentary rocks. These features cannot account for stream sediment derived from schist. Observed lithologic heterogeneity of stream sediment therefore suggests that large-scale mass movement is only one part of a complex suite of processes supplying sediment to streams in this basin. Other significant sediment contributors include various forms of fluvial erosion and small-scale discrete mass failures, particularly on oversteepened hillslopes adjacent to perennial streams. Photo-interpretive studies of landslide and timber-harvest history adjacent to Redwood Creek, together with analysis of regional precipitation and runoff records for six flood-producing storms between 1953 and 1975, indicate that loci and times of significant streamside landsliding are influenced by both local storm intensity and streamside logging. Analysis of rainfall records and historic accounts indicates that the individual storms comprising a late-19th-century series of storms in northwestern California were similar in magnitude and spacing to those of the past 25 years. The recent storms apparently initiated more streamside landslides than comparable earlier storms, which occurred prior to extensive road construction and timber harvest. Field observations and repeated surveys of stake arrays at 10 sites in the basin indicate that earthflows are especially active during prolonged periods of moderate rainfall; but that during brief intense storms, fluvial processes are the dominant erosion mechanism. Stake movement occurs mostly during wet winter months. Spring and summer movement was detected at some moist streamside sites. Surveys of stake arrays in two recently logged areas did not indicate exceptionally rapid rates of movement in three years following timber harvest.

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USGS1976

Erosional landform map of the Redwood Creek drainage basin, Humboldt County, California, 1947-74

Landslides and actively eroding stream channels disrupt roads, damage valuable timberland, and increase stream sediment loads in northwestern California. This 1:62,500 photointerpretative map shows the distribution of ten common types of fluvial and mass-movement erosional landforms in the drainage basin of Redwood Creek in 1947 and 1974. The mapped landforms include slides, slumps, large compound earthflows, debris avalanches, unstable streambanks and adjacent hillslopes, small mass-movement features, questionable or inactive landslides, deeply incised amphitheater shaped drainage basins, small actively eroding water courses, and actively eroding main channel stream banks. The map legend describes these landforms and the techniques used in preparing the map. The amount and diversity of erosional activity increased greatly between 1947 and 1974. This increased activity apparently reflects major floods in 1953, 1955, 1964, and 1972, as well as the start of large scale, tractor-yarded clearcut timber harvest in the basin. (Woodard-USGS)

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