Difference between revisions of "Alteration of instream habitat"

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==Effect/Impact on (including literature citations)==
 
==Effect/Impact on (including literature citations)==
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*HYMO (general and specified per HYMO element)
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All hydromorphological pressures affect instream habitat, but in this section, we refer to those pressures that directly destroy the aquatic habitat, such as channel dredging and mining, and the reinforcement of channel bed and banks with introduced materials such as concrete or rip-rap. These activities generally reduce channel boundary roughness, leading to increased flow velocities and other consequences similar to those resulting from channelization. Assessing the effects of these specific pressures is difficult due to their association with other potential habitat-altering variables. For example, increases in turbidity and siltation can easily arise from
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*physico - chemical parameters
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agricultural land use (i.e. cattle grazing) in both channelized and reference streams.
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*Biota (general and specified per Biological quality elements)
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==Case studies where this pressure is present==
 
==Case studies where this pressure is present==
 
<Forecasterlink type="getProjectsForPressures" code="P15" />
 
<Forecasterlink type="getProjectsForPressures" code="P15" />

Revision as of 08:44, 1 September 2015

Alteration of instream habitat

04. Morphological alterations

General description

Natural instream habitats offer refuge and shelter, food resources and spawning grounds to aquatic biota. Recognition of instream habitat alteration should be based on changes in surface flow type, hydraulic attributes (flow depth, velocity and bed roughness, shear velocity, Reynolds and Froude numbers), channel morphology, and bed substrate calibre. Instream habitat degradation may be an effect of a hydrogeomorphological process (natural or caused by other pressures), or of a direct human activity (e.g. channel dredging, gravel bed extraction). The latter activities are those pressures we are refering to here.

Effect/Impact on (including literature citations)

All hydromorphological pressures affect instream habitat, but in this section, we refer to those pressures that directly destroy the aquatic habitat, such as channel dredging and mining, and the reinforcement of channel bed and banks with introduced materials such as concrete or rip-rap. These activities generally reduce channel boundary roughness, leading to increased flow velocities and other consequences similar to those resulting from channelization. Assessing the effects of these specific pressures is difficult due to their association with other potential habitat-altering variables. For example, increases in turbidity and siltation can easily arise from agricultural land use (i.e. cattle grazing) in both channelized and reference streams.

Case studies where this pressure is present

Possible restoration, rehabilitation and mitigation measures

Useful references

Other relevant information

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