scholarly journals Hydrogeomorphic effects on bedload scour in bull char (Salvelinus confluentus) spawning habitat, western Washington, USA

2010 ◽  
Vol 67 (4) ◽  
pp. 626-640 ◽  
Author(s):  
Jeffrey G. Shellberg ◽  
Susan M. Bolton ◽  
David R. Montgomery
Keyword(s):  
Woody Debris ◽  
Main Channel ◽  
Spawning Habitat ◽  
Stream Power ◽  
Salvelinus Confluentus ◽  
Channel Change ◽  
Gravel Beds ◽  
Side Channels ◽  
Western Washington ◽  
Sand And Gravel

We investigated the vulnerability of fall-spawned bull char ( Salvelinus confluentus ) embryos to redd scour during winter rain and rain-on-snow flood discharges in western Washington, USA. It was hypothesized that the magnitude of bedload scour at bull char redds is reduced by the provision and selection of stable refugia habitat controlled by local-, reach-, or subcatchment-scale variables such as hydraulic habitat unit and channel type. Bedload scour and channel change were measured using 96 scour monitors and 34 elevational transects in three catchments over 2 to 4 years. Scour to cited egg burial depths of bull char did not commence until discharge typically exceeded the 2-year recurrence interval. At a local scale, scour varied significantly among side channel, protected main channel, and unprotected main channel redd sites. Unprotected gravel patches in simplified channel types with moderate gradients were most susceptible to deep scour, especially if coupled with the transient supply and storage of sand and gravel from mass wasting. Partially transport-limited reaches had reduced scour due to lower stream power and armored gravel beds. Complex spawning habitat (i.e., with abundant large woody debris and side channels) was important in providing refuge from deep scour and in buffering embryos against inhospitable hydrologic or sediment regimes.

Organic detritus particles: Initiation of motion criteria on sand and gravel beds

1983 ◽  
Vol 19 (6) ◽  
pp. 1627-1631 ◽  
Author(s):  
John S. Fisher ◽  
Ben L. Sill ◽  
Douglas F. Clark
Keyword(s):  
Organic Detritus ◽  
Gravel Beds ◽  
Sand And Gravel

Bed configuration and microscale processes in alluvial channels

1993 ◽  
Vol 17 (2) ◽  
pp. 123-136 ◽  
Author(s):  
André Robert
Keyword(s):  
Probabilistic Approach ◽  
Field Measurements ◽  
Bedload Transport ◽  
Transport Processes ◽  
Coarse Grained ◽  
Small Scale ◽  
Alluvial Channels ◽  
Gravel Beds ◽  
Sand And Gravel ◽  
Bed Material

Numerous recent studies on fluvial processes, both in Canada and internationally, have focused on small-scale phenomena. Investigations on the characterization of surface roughness in coarse-grained channels and its links with flow resistance and sediment transport processes have been a dominant field of research. Closely related is a second major area of investigation on turbulent flow structures in boundary layers over both sand and gravel beds and their relations with the transport of bed material. Phenomena potentially related to 'bursting' have been shown to control bedload transport processes and the concentration of sediment in suspension. Detailed investigations have also been conducted on the links between flow turbulence, bed material movement, and bed morphology at channel junctions. Finally, selective entrainment and transport of individual coarse particles have been studied from field measurements and laboratory experi ments. Emphasis has been put on bed microtopography, surface structure and texture, and on a probabilistic approach to bedload transport.

scholarly journals Tectonic Influence on Speleogenesis of Sea Caves on Biševo Island (UNESCO Global Geopark Vis Archipelago, Adriatic Sea, Croatia)

Geosciences ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 341
Author(s):  
Ivan Mišur ◽  
Marko Budić ◽  
Tomislav Kurečić ◽  
Tvrtko Korbar
Keyword(s):  
Host Rock ◽  
Adriatic Sea ◽  
Strike Slip ◽  
Main Channel ◽  
Fault System ◽  
Quaternary Sediments ◽  
Tidal Zone ◽  
Tectonic Regime ◽  
Side Channels ◽  
Host Rocks

A geological and speleological investigation was conducted in the famous Blue Cave (Modra špilja) and the Monk Seal Cave (Medvidina špilja) on Biševo Island (Croatia) to promote the island’s geoheritage through the new Visitor Centre. The island is mainly composed of Cretaceous to Paleogene neritic carbonates, which form the bedrock, whereas parts of the island are covered with thin Quaternary sediments. The caves are of small dimensions and a simple layout, composed of the main channel and few shorter side channels, all positioned in the tidal zone. Thus, the caves are semi-submerged sea caves located along the coastline. The Blue Cave and the Monk Seal Cave developed within the bedrock limestones and dolostones, respectively, within a zone of left-lateral NNE–SSW striking strike-slip faults that belong to the Biševo fault system. Conjugated discontinuities within the carbonate bedrock indicate a specific strike-slip tectonic regime. Additionally, the host rocks were probably also deformed and fractured during the rise of salt diapirs that characterise this part of the Adriatic foreland. Tectonic and bedding discontinuities form the fragments of the host rock, that combined with the impacts of the strong southern waves, significantly influenced the genesis of the caves.

November: Beavers to the Rescue

2019 ◽  
Author(s):  
Ellen Wohl
Keyword(s):  
Main Channel ◽  
Filamentous Algae ◽  
Snow Surface ◽  
Side Channels

By late November, snow covers much of the beaver meadow. I visit on a sunny day well above freezing, but the low-angle light comes with long, long shadows. The meadow is noisy with continuously rushing wind that keeps the bare willow branches swaying and sculpts the snow on the lee side of plants into streamlined mounds. Individual grass stems have traced downwind crescents on the snow surface. Tracks of wind, tracks of animals: the activities of the meadow are once again made visible in the footprints of moose, hare, squirrel, coyote, and birds. The snow is mushy in the warmth and many of the tracks are blurred, but I also cross fresh, sharply defined traces left by four little leaping paws, with just the brush from a long, slender tail behind them. The prints are so delicate that they barely indent the snow, but clearly a mouse was stirring here recently. The fragile tracery of tiny claws in the snow seems vulnerable, but I know the animal is probably better adapted to the cold than I am. The main channel of the creek remains open, the water golden brown between white banks bulbed with ice along the edges. The creek flows quietly, the sound of moving water submerged beneath the wind. The larger side channels also remain open and green with filamentous algae, but I break through the snow-covered thin ice on the smallest side channels. The off-channel ponds are frozen more solidly. Mats of dried algae quiver in the wind on one newly drained pond. Downwind, the snow is dirty with silt blown from the exposed bed. A layer of sticks, sand, and muck floors the pond with a woody carpet created by the beavers. The main beaver lodge is freshly plastered with mud and sticks, but the ice on the surrounding pond remains unbroken and the snow is trackless. Away from the pond, snow into which I sink to mid-calf obscures the details of the ground. The upright stems of willows and aspen trunks dominate the foreground.

scholarly journals Seasonal timing of reproductive migrations in adfluvial bull trout: an assessment of sex, spawning experience, population density, and environmental factors

2018 ◽  
Vol 75 (12) ◽  
pp. 2172-2183 ◽  
Author(s):  
R. Niloshini Sinnatamby ◽  
Madalena C. Pinto ◽  
Fiona D. Johnston ◽  
Andrew J. Paul ◽  
Craig J. Mushens ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Upstream Migration ◽  
Swimming Ability ◽  
Bull Trout ◽  
Spawning Habitat ◽  
Salvelinus Confluentus ◽  
Intrinsic Factors ◽  
Migration Timing ◽  
First Time ◽  
Experienced Female

Using individual tags combined with a fish fence operated at the mouth of Smith-Dorrien Creek, the primary spawning habitat for Lower Kananaskis Lake bull trout (Salvelinus confluentus), we approximated a complete census of the spawning population from 1996 to 2000 to assess whether timing of upstream and downstream spawning migrations varied with extrinsic and intrinsic factors. The timing of both upstream and downstream migrations varied with sex, previous spawning experience, density, and temperature. Inferred spawning duration based on the predicted upstream and downstream migration dates indicated that experienced female spawners spent the least amount of time upstream and first-time spawners spent the most time upstream. No consistent differences in upstream migration timing were observed between non-repetitive and repetitive spawners. We suggest that variations in spawning migration timing observed in Lower Kananaskis Lake may be linked to environmental factors that influence upstream swimming ability and acquisition and expenditure of energy with respect to reproduction.

Wood Dynamics in Coastal Plain Blackwater Streams

1990 ◽  
Vol 47 (1) ◽  
pp. 92-99 ◽  
Author(s):  
Arthur C. Benke ◽  
J. Bruce Wallace
Keyword(s):  
Coastal Plain ◽  
Woody Debris ◽  
Habitat Type ◽  
Dry Mass ◽  
Main Channel ◽  
Sixth Order ◽  
Stream Channels ◽  
River Continuum ◽  
Temperate Deciduous Forests ◽  
Ogeechee River

We quantified woody debris in the river swamps of the sixth order Ogeechee River and several smaller tributaries in the Coastal Plain of the southeastern USA, compared swamp wood with woody debris in the channel, and studied wood movement in the swamp and main channel over 20 mo. Woody debris in the Ogeechee River swamps was relatively low (0.362–0.880 kg ash-free dry mass (AFDM)/m2) in comparison to several mixed temperate deciduous forests. Similarly, wood in the tributary swamps was low (mean = 0.82 kg AFDM/m2), and there were no trends along the river continuum. Wood in the channels of both the Ogeechee (6.46 kg AFDM/m2) and a fourth order tributary (2.24 kg AFDM/m2) were significantly higher than found in their adjacent floodplains. Woody debris appeared to increase in stream channels from smaller tributaries to the sixth order river, opposite of that observed in other river systems. Tagging of logs showed that only 17% of wood in the Ogeechee channel had moved after 3 major floods, much less than in the swamps (21–84%). The abundance and stability of woody debris in the main channel allows it to be a major habitat type and source of food for both riverine invertebrates and fishes. The fate of most swamp wood appears to be decomposition and fragmentation, rather than import to the river channel.

Empirical relationships between watershed characteristics and coho salmon (Oncorhynchus kisutch) smolt abundance in 14 western Washington streams

2001 ◽  
Vol 58 (7) ◽  
pp. 1453-1463 ◽  
Author(s):  
Rishi Sharma ◽  
Ray Hilborn
Keyword(s):  
Coho Salmon ◽  
Woody Debris ◽  
Oncorhynchus Kisutch ◽  
Empirical Relationships ◽  
Watershed Characteristics ◽  
Valley Slope ◽  
Two Measures ◽  
Western Washington ◽  
Lower Stream ◽  
Habitat Variables

We assembled data on coho salmon (Oncorhynchus kisutch) from 14 streams in western Washington, including annual smolt counts and annual escapement, either as absolute counts or as an index. We also compiled data on large woody debris (number·km%#150;1 of stream), road densities in the watersheds (km road·km%#150;2), gradient of the streams (%), valley slope adjacent to the stream (%), drainage area in the watershed (km2), and pool, pond, and lake areas (m2·km%#150;1). We explored the relationships between habitat variables and two measures of coho production, the maximum production of smolts in the stream (capacity) and the maximum smolts/spawner (productivity). Using the 11 streams with pool and pond counts, we found that pool and pond densities served as good predictors of smolt density (r2 = 0.85 for pools and 0.68 for ponds, independently). Pools produced 0.39 smolts·m%#150;2 and ponds produced 0.07 smolts·m%#150;2 in the multiple regression fit, accounting for 92% of the residual error. We also found that lower valley slopes, lower road densities, and lower stream gradients were correlated with higher smolt density.

Large woody debris in bull trout (Salvelinus confluentus) spawning streams of logged and wilderness watersheds in northwest Montana

1999 ◽  
Vol 56 (6) ◽  
pp. 915-924 ◽  
Author(s):  
F Richard Hauer ◽  
Geoffrey C Poole ◽  
John T Gangemi ◽  
Colden V Baxter
Keyword(s):  
Woody Debris ◽  
Rocky Mountain ◽  
Large Woody Debris ◽  
Mountain Streams ◽  
Bull Trout ◽  
Stream Channel ◽  
Salvelinus Confluentus ◽  
Stream Bank ◽  
Northwestern Montana ◽  
Bankfull Width

We measured large woody debris (LWD) in 20 known bull trout (Salvelinus confluentus) spawning stream reaches from logged and wilderness watersheds in northwestern Montana. Mean bankfull width of stream reaches was 14.1 m ranging from 3.9 to 36.7 m. Streams were large enough to move LWD and form aggregates. We determined the characteristics of individual pieces of LWD that were interactive with the stream channel. Large, short pieces of LWD attached to the stream bank were the most likely to be positioned perpendicular to stream flow, while large, long pieces either tended to be parallel to the flow or, when attached, were most apt to extend across the channel thalweg. Observations indicated that the majority of pools were formed as scour pools by either very large LWD pieces that were perpendicular to the stream or multipiece LWD aggregates. Among reaches in wilderness watersheds, ratios of large to small LWD, attached to unattached LWD, and with and without rootwads were relatively consistent. However, among reaches with logging in the watershed, these ratios varied substantially. These results suggest that logging can alter the complex balance of delivery, storage, and transport of LWD in northern Rocky Mountain streams, and therefore, the likely substantive change in stream habitats.

scholarly journals Recent river channel change detections in the section of the River Tisza above Tiszaújlak (BИЛОК)

2016 ◽  
Vol 10 (3-4) ◽  
pp. 123-130 ◽  
Author(s):  
István Kolozsvári ◽  
József Molnár ◽  
György Dévai
Keyword(s):  
Satellite Images ◽  
Google Earth ◽  
Formation Processes ◽  
Security Risks ◽  
Channel Change ◽  
Side Channels ◽  
Plant Coverage ◽  
Tisza River ◽  
The Right ◽  
River Channel Change

In the section above Tiszaújlak, despite the presence of embankments, the River Tisza shows active meandering tendency and it splits into branches resulting in side channels, dead channels and backwaters that follow the main channel. In our work we examined the right- and the left-side riverbank sections of the River Tisza, between Tiszaújlak (Вилок) and Tiszasásvár (Тросник), as well as between Tiszaújlak and Tiszapéterfalva (Пийтерфолво), to reveal the extent of bar depositions between 2006 and 2015, and to what extent the intensity and direction of the riverbank formation processes were influenced by the material of the bank and the plant coverage, its rate and characteristics. We tried to reveal which sections were eroded by the river and what security risks they have for the safety of the settlements along the Tisza River. On the right side of the Tisza River riverbank 51, and on the left side 62 main measuring points were recorded by GPS positioning satellite in 2009, 2010 and 2015. Our results were compared to the satellite images of Google Earth taken in 2006, too. According to our experience, in several bends of the examined sections of the river, active bar deposition can be observed; in some cases more than 100 m of bar depositions were detected.

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