Ecohydraulics

[3] For example, the International Association for Hydro-Environment Engineering and Research (IAHR) and Taylor & Francis have been publishing the Journal of Ecohydraulics since 2016.

Asian carp lay floating eggs when they sense increasing discharge resulting from a spring flood flow.

[8] On the other hand, low vertical mixing or turbulence is a key factor in favoring the development of harmful algal blooms.

[9][10] Reservoirs are operated according to the requirements of power generation, water supply, navigation, and, in recent decades, environmental flows.

The instantaneous fluctuation in flow discharge and velocity kills most species except for those (e.g., the small shrimp, Palaemonidae) that can hide in crevices in riverbed sediment.

[12] Some dragonfly species on the Tibetan Plateau live for more than ten years in cold water before attaining sexual maturity and eclosion.

A wide variety of flow velocities, water depths, and temperatures, both spatial and temporal, are needed to maintain high levels of biodiversity in aquatic ecosystems.

Real-time monitoring and early warning systems can help with adaptive management to mitigate the harmful effects of massive algal blooms.

[16] Emergent and submerged vegetation change the turbulence structure and sediment transportation,[17][18] and may cause these quantities to vary with flow velocity over a floodplain.

Habitat is an area where plants or animals normally live, grow, feed, reproduce, and otherwise exist for any portion of their life cycle.

The slope, planform, confinement, and cross-sectional shape and dimensions of a stream, and the grain-size distribution of bed sediment affect aquatic habitat.

Substrate is a general term that refers to all material that constitutes a riverbed or stream bed, which in most cases mainly comprise sediment.

[20] Hyporheic zone is a layer of substrate on the riverbed in which benthic animals normally live or exist for any portion of their life cycle.

Other species prefer the stream bed surface for its higher DO concentration, direct contact with flowing water, and high food availability.

Field investigations have shown that a stream with different substrates is suitable for a large variety of invertebrate species and has a high biodiversity.

The Yangtze River once connected thousands of riparian lakes in its middle and lower reaches, thereby forming a complex habitat system.

Experiments have shown that a substantial reduction in the number of species and the abundance of macro-invertebrates occurs within 4 months after a riparian wetland is isolated from the river.

The resilience of an eco-system involves both the process and the outcome of successfully adapting to ecological stresses, and the ability to maintain its normal patterns of biomass production after being subjected to damage.

A new paradigm in river and coastal management is evolving ecological enhancement, recreation, and aesthetics, as well as complying with strict environmental protection legislation.

These complex projects require extensive data and simulation tools to assist decision makers and communities in selecting management strategies which offer the maximum benefits, whilst preserving and enhancing the ecological integrity of the river system.

Physical habitat models are particularly useful for assessing the impact of hydropower projects, analyzing the effects of water abstraction on river ecology, and determining the minimum flow requirements of aquatic populations.

Brood fish seek suitable spawning sites and adhere fertilized eggs to stones, which hatch after about 120 to 150 h. Juvenile sturgeon swim to the East China Sea and stay there until they reach maturity.

Using these curves, the Habitat Suitability Index (HSI) was calculated, in which the velocity, depth, temperature, and substrate were estimated using a two-dimensional model of hydraulics and sediment movement.

[43] More than 130 dams have been built on the Columbia River and its tributaries, blocking salmon spawning upstream, resulting in a fishery loss of $6.5 billion between 1960 and 1980.

The main concept of fish ladder design is to create extremely high resistance, letting the water from upstream to downstream of the dam flow at a low velocity while maintaining a large depth.

[45] The ladder consists of a series of baffles positioned on the walls and floor of a channel all of which enable the upstream moving brood fish, specifically Atlantic salmon, to bypass weirs and small dams.

Myriophyllum and Periphyton (forms of algae) grew on the riverbed, and the original white gravel bed was covered with green aquatic plants.

Reintroduction of flow through remnant river channels increased habitat diversity and led to favorable responses by fish and invertebrate communities.

By making use of natural processes such as waves, wind and tide to redistribute the sand, this innovative approach succeeded in limiting the disturbance of local ecosystems, while also providing new areas for nature and more types of recreation[58] Ecohydraulics for restoring habitat of migratory birds (South Korea)- Nakdong River estuary is regulated by a 2,400-meter-long dam built in 1987 to control the inflow of seawater into farmland and secure drinking and agricultural water for nearby regions, including Busan, Ulsan and South Gyeongsang Province (Figure 4).

A tidal flat was formed towards the seaside where the sand and mud carried over along the river accumulates provides fertile soil, rendering the area agriculturally rich and the habitat for migratory birds restored.