China
Africa
Explore chapters and articles related to this topic
Water Ecology
Published in Frank R. Spellman, Handbook of Water and Wastewater Treatment Plant Operations, 2020
Rocks are not the only physical features of streams where aquatic organisms can be found. For example, fallen logs and branches (commonly referred to as large woody debris, or LWD), provide an excellent place for some aquatic organisms to burrow into and surfaces for others to attach themselves, as they might to a rock. They also create areas where small detritus such as leaf litter can pile up underwater. These piles of leaf litter are excellent shelters for many organisms, including large, fiercely predaceous larvae of dobsonflies.
Probabilistic risk assessment framework for predicting large woody debris accumulations and scour near bridges
Published in Structure and Infrastructure Engineering, 2023
William Hughes, Leana Santos, Qin Lu, Ramesh Malla, Nalini Ravishanker, Wei Zhang
A risk-based predictive model for large woody debris accumulations around bridge piers was developed to forecast bridge vulnerability based on the upstream vegetation, soil, and river conditions under storm events. The framework takes an important step toward a comprehensive evaluation of drift buildup susceptibility and quantification, which remains an area of pressing research need. Due to the complexities of multiple interacting variables, as well as lacking empirical data, such studies have to date been limited despite the major threat posed by woody debris buildups around bridges. The present model addresses such research gaps by including the physics-based risk assessment of the local vegetation and the resultant debris generation and entrapment probabilities in an integrated framework to predict scour with combined debris accumulations.
Performance of constructed fish spawning and rearing channels – development of the Imatra City Brook in Finland
Published in Journal of Ecohydraulics, 2022
Jukka Jormola, Antti Haapala, Kirsti Leinonen, Markus Tapaninen, Pekka Vähänäkki, Saija Koljonen
In Sweden, Nyqvist et al. (2017) noted that when a technical fish pass was replaced by a near-natural bypass channel, the migration of adult salmon increased in upstream and downstream directions. In a study on 23 Swedish bypass channels, the channels were found to host the same fish communities as natural river sections, indicating their potential as compensatory habitats (Tamario et al. 2018). The nature-like fishway at the Eldforsen Power Plant, Sweden, was constructed with an emphasis on creating diverse aquatic habitats (Gustafsson 2017). Within two years, the channel contained macroinvertebrates with a functional feeding group (FFG) composition similar to that of natural brooks. The ratio of different groups showed that, rather than resembling a small forest brook, the channel was more similar to the main stem of a large river. Large woody debris was preferred in the habitat selection of introduced brown trout, which indicated that new channels benefit from added wood material.
Effectiveness monitoring of juvenile Chinook salmon restoration projects in south Lake Washington, Washington State
Published in Lake and Reservoir Management, 2022
Roger A. Tabor, Martin C. Liermann, Howard A. Gearns, Zachary J. Moore, Katherine D. Lynch, Keith Kurko, Julie Crittenden, Monica E. Shoemaker
Log jams appear to provide valuable habitat for juvenile Chinook salmon; however, how much large woody debris is needed is not well known. At the Shuffleton Flume site there were 3 ELJs and one small natural log jam spread out over a roughly 300 m long shoreline section, representing about 15% of the shoreline. South Lake Sammamish (a smaller lake connected to Lake Washington) has a natural 300 m long structurally complex shoreline section with large and small woody debris and emergent vegetation, and juvenile Chinook salmon primarily used the 2 opposite ends of this complex shoreline that are adjacent to open beaches (Tabor and Piaskowski 2002). This may indicate the influence of an edge effect where juvenile Chinook salmon primarily use the periphery of the log jam, which enables them to easily retreat to cover when needed but also allows them to move into open shorelines to forage and rest at night. The ELJs at the Shuffleton Flume were 10 to 15 m wide which may be closer to an ideal size that provides a balance of cover and forage opportunities while larger ELJs than these may not provide much additional benefit and thus may be less cost-effective. The ELJs at the Shuffleton Flume were spaced 100 to 130 m apart. Placing ELJs closer together may be beneficial, but the ideal distance between ELJs is not known.