Difference between revisions of "Remove barrier"

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Depending of its height, all dams suppose a more or less impassable barrier for the  fish migratory species of the river, and concern the dispersion of the seeds, drift of macroinvertebrates, and transport and distribution of the sediments along the riverbed.
 
Depending of its height, all dams suppose a more or less impassable barrier for the  fish migratory species of the river, and concern the dispersion of the seeds, drift of macroinvertebrates, and transport and distribution of the sediments along the riverbed.
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To avoid this barrier effect, in many cases it is possible and suitable, to built fish passes, by-pass channels, fish elevators or any other system that is considered to be appropriate. But in many other cases, the most suitable and effective measure will be to proceed to reduce the height of the dam, or even the demolition of the dam, in order to restore the primitive(original) conditions of the river.
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To avoid this barrier effect, in many cases it is possible and suitable, to built fish passes, by-pass channels, fish elevators or any other system that is considered to be appropriate. But in many other cases, the most suitable and effective measure will be to proceed to reduce the height of the dam, or even the demolition of the dam, in order to restore the primitive conditions of the river.
  
 
The elimination of dams and weirs or obstacles for the pass of the waters and the aquatic organisms is a habitual practice in many countries in order to recover the ‘fluvial continuity’, which is an indicator of the Hydro-morphological quality of the running waters water bodies as Water Framework Directive proposes. In United States an increased experience on dam demolition (International Rivers Network, 2001; Bednarek, 2001; Higgs, 2002) exists, considering that these have a limited life span, and that often the environmental impacts that they generate are not justified by its use or current exploitation.
 
The elimination of dams and weirs or obstacles for the pass of the waters and the aquatic organisms is a habitual practice in many countries in order to recover the ‘fluvial continuity’, which is an indicator of the Hydro-morphological quality of the running waters water bodies as Water Framework Directive proposes. In United States an increased experience on dam demolition (International Rivers Network, 2001; Bednarek, 2001; Higgs, 2002) exists, considering that these have a limited life span, and that often the environmental impacts that they generate are not justified by its use or current exploitation.

Revision as of 13:03, 13 July 2010

Remove barrier

Remove barrier04. Longitudinal connectivity improvement

General description

At present there are many barriers in the rivers that might be eliminated due to their lack of use, obtaining with it the longitudinal continuity of the flows and the connectivity of the fluvial habitat recovery. Barriers are obstacles to the natural flows longitudinal continuity, represented by hydraulic engineering transverse structures, including large dams, weirs, and dikes. The aim of this measure is to recover the continuity of water and sediment flows, and the organism connectivity in both ways, in order to recover the principal attributes of natural functioning rivers. The elimination of these barriers will be possible only in the cases in which the property, the use or the purpose allow it, attending to the in force legislation and to the agreements that could be reached between the social implied agents.

Many of these river transverse barriers are nowadays in disuse, or its use has diminished in intensity or profitability, and the ecological functioning alteration caused is not justified any more, being necessary to check the interest of its maintenance, or the possibility of their removal.

Depending of its height, all dams suppose a more or less impassable barrier for the fish migratory species of the river, and concern the dispersion of the seeds, drift of macroinvertebrates, and transport and distribution of the sediments along the riverbed. To avoid this barrier effect, in many cases it is possible and suitable, to built fish passes, by-pass channels, fish elevators or any other system that is considered to be appropriate. But in many other cases, the most suitable and effective measure will be to proceed to reduce the height of the dam, or even the demolition of the dam, in order to restore the primitive conditions of the river.

The elimination of dams and weirs or obstacles for the pass of the waters and the aquatic organisms is a habitual practice in many countries in order to recover the ‘fluvial continuity’, which is an indicator of the Hydro-morphological quality of the running waters water bodies as Water Framework Directive proposes. In United States an increased experience on dam demolition (International Rivers Network, 2001; Bednarek, 2001; Higgs, 2002) exists, considering that these have a limited life span, and that often the environmental impacts that they generate are not justified by its use or current exploitation.

Applicability

Expected effect of measure on (including literature citations):

  • HYMO (general and specified per HYMO element)
  • physico � chemical parameters
  • Biota (general and specified per Biological quality elements)

Temporal and spatial response

Pressures that can be addressed by this measure

Cost-efficiency

Case studies where this measure has been applied

Useful references

Other relevant information

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