Ecological and Hydraulic Studies of Step-Pool Systems

The ecological and hydraulic features of step-pool systems are studied by field investigation, measurement, sampling, and analysis. The study is done on Shengou and Jiuzhai Creeks, where step-pool systems have developed, Fork Gully, where a step-pool system is developing, and the Jinsha River and Ji...

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Bibliographic Details
Published in:Journal of hydraulic engineering (New York, N.Y.) N.Y.), 2009, Vol.135 (9), p.705-717
Main Authors: Wang, Zhao-yin, Melching, Charles Steven, Duan, Xue-hua, Yu, Guo-an
Format: Article
Language:English
Subjects:
Banks
Biodiversity
Boulders
China
Density
Deposits
Ecological monitoring
Ecology
Erosion resistance
Floods
Flow resistance
Fluid dynamics
Fluid flow
Freshwater
Gravel
Gullies
Habitats
Hydraulic engineering
Hydraulics
Inertia
Pools
Ravines
River beds
Rivers
Sampling
Sand
Sediments
Spatial distribution
Stability
Streambeds
Streams
TECHNICAL PAPERS
Water depth
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Summary:The ecological and hydraulic features of step-pool systems are studied by field investigation, measurement, sampling, and analysis. The study is done on Shengou and Jiuzhai Creeks, where step-pool systems have developed, Fork Gully, where a step-pool system is developing, and the Jinsha River and Jiangjia and Xiaobaini Ravines, where there is no step-pool system. Boulders, cobbles, and gravel tightly interlock and form the steps having an inherent stability that only extreme floods are likely to disturb. Gravel and sand deposit in the pools behind the steps. These steps and pools provide high diversity of habitat for the stream biocommunity. The density of benthic macroinvertebrates in streams with step-pool systems is several 100 times higher than neighboring streams without step-pool systems. A new habitat diversity index is proposed considering the spatial distribution of various substrates, velocity, and water depth. The study reveals that the biodiversity of benthic macroinvertebrates increases with habitat diversity. Measurements with a specially designed instrument were done to study the development of step-pool systems and its effects on resistance to the flow and stream bed stability. A step-pool system maximizes the flow resistance and protects the bed sediment from erosion. Thus, the riverbed and bank slope are stabilized. The development degree of step pools is proportional to the streambed slope. The bed resistance increases with the development degree of step pools. Riverbed inertia represents the stability of the streambed. The development of step-pool systems greatly increases the riverbed inertia, and, therefore, maximizes streambed stability.
ISSN:0733-9429
1943-7900
DOI:10.1061/(ASCE)0733-9429(2009)135:9(705)