Search results
Results from the WOW.Com Content Network
Anthropogenic activities also include discrete elements like the use of fire, domestication of plants and animals, soil development, the establishment of settlements and irrigation. [3] River ecosystems have been transformed downstream from the point of pollution.
This stream operating together with its environment can be thought of as forming a river ecosystem. River ecosystems are flowing waters that drain the landscape, and include the biotic (living) interactions amongst plants, animals and micro-organisms, as well as abiotic (nonliving) physical and chemical interactions of its many parts.
Ecohydraulics is an interdisciplinary science studying the hydrodynamic factors that affect the survival and reproduction of aquatic organisms and the activities of aquatic organisms that affect hydraulics and water quality. Considerations include habitat maintenance or development, habitat-flow interactions, and organism responses.
The theory is based on the concept of dynamic equilibrium in which streamforms balance between physical parameters, such as width, depth, velocity, and sediment load, also taking into account biological factors. [2] It offers an introduction to map out biological communities and also an explanation for their sequence in individual sections of ...
The river's discharge at that location depends on the rainfall on the catchment or drainage area and the inflow or outflow of groundwater to or from the area, stream modifications such as dams and irrigation diversions, as well as evaporation and evapotranspiration from the area's land and plant surfaces. In storm hydrology, an important ...
However the grains will continue to be transported even if the velocity falls below the entrainment velocity due to the reduced (or removed) friction between the grains and the river bed. Eventually the velocity will fall low enough for the grains to be deposited. This is shown by the Hjulström curve.
Rapids cause water aeration of the stream or river, resulting in better water quality. [2] For a rapid to form, a necessary condition is the presence of a gradient, which refers to the river or stream's downward slope. When a river has a larger gradient, the water flows downhill faster. [3] Gradients are typically measured in feet per mile. [4]
A major effect of river engineering has been a reduced sediment output of large rivers. For example, the Mississippi River produced 400 million tons of sediment per year. [ 22 ] Due to the construction of reservoirs , sediment buildup in man-made levees , and the removal of natural banks replaced with revetments , this sediment output has been ...