Remeandering straightened rivers

Description of measure

Many river channels have been historically straightened to increase conveyance, improve navigability or accommodate floodplain development (e.g. straightening undertaken as part of railway construction).  This measure refers to the remeandering of straightened river channels, through both creation of a new meandering course and reconnection of cut off meanders. 

Application

This measure is applicable to river systems that would naturally be expected to have a meandering planform but have been modified.  It is not appropriate to create meanders within a river system that would not naturally meander through lateral adjustment, such as high gradient headwater systems are adjusting predominantly in the vertical plane. 

It should be noted that some straightened river reaches may begin to remeander naturally (e.g. Lewin et al., 1988; Brookes, 1992).  If signs of natural adjustment are present (e.g. bank erosion), artificial remeandering may not be necessary.  It is therefore suggested that a detailed assessment is undertaken by an experienced geomorphologist prior to the initiation of remeandering works. 

Benefits for Water Framework Directive

Re-meandering straightened river channels can help deliver objectives of the WFD by:

  • Increasing morphological and flow diversity in a straightened river channel.  These more natural conditions can provide better quality habitats for macrophytes and benthic invertebrates, and as a result also improve habitats for fish. 

In addition to improving conditions for the biological quality elements, remeandering could also help to improve habitats for birds and mammals that prey on fish and invertebrates.   Remeandering increases the length of a straightened river channel.  This decreases flow conveyance, which can effectively store water in the river channel.  Remeandering can therefore decrease flood risk to sites further downstream, by reducing hydrological response times during periods of high flows. 

To read more about the effectiveness of the measure within academic literature please click here: Effectiveness for Biological Quality Elements

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