Property:Monitoring surveys and results
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This is a property of type Text.
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Photographs pre-works<br>Pre-project data: specify above +
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Please see the parent project (River Wandle Restoration Project) for the final results on this work, combined with the other phases. +
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Please see the parent project (River Wandle Restoration Project) for the final results on this work, combined with the other phases. +
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Please see the parent project (River Wandle Restoration Project) for the final results on this work, combined with the other phases. +
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Please use the link to find out about the Electrofishing surveys for the project http://www.norfolkriverstrust.org/wp-content/uploads/2016/02/Electrofishing-doc.pdf +
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Post works monitoring is essential for evaluating the physical and ecological performance of the project. Given the near unique scale of application of the ‘process-based’ restoration approach, the project provided an invaluable opportunity to monitor how the river environment responds to the various components of the implemented works, providing valuable insight and guidance for the application of this type of approach in other areas.
Specific monitoring has included:
• Repeat topographic/ bathymetric surveys (immediately post-construction and subsequent to three high flow events flood events).
• Repeat sediment sampling (pre- and post- implementation)
• Repeat fixed-point photographs
• Repeat spawning surveys/ redd counts (including pre-works and the two spawning seasons post-construction)
• Repeat electro-fishing surveys (in both channel and wetland locations, pre- and post-works)
Immediately after construction, a detailed topographic and sedimentary resurvey were carried out. Further resurveys have been undertaken after significant flow events, determining rapid evolution of the site and in the trajectory intended (and predicted by modelling).
Given fish populations are a good indicator of habitat condition, repeat red counts and electro-fishing surveys have also been undertaken. Latest survey results show significant increases in spawning and juvenile salmon and trout compared to pre-restoration conditions, providing an ‘ecological validation’ the works implemented. +
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Post-project Appraisal +
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Pre and post photographs were taken. A standard maintenance post audit form was completed 9 months after the project was completed. Annual photography is used to monitor the project. Assessment carried out during photography shows that the channel is maintaining itself overall, with fish present (which had not been the case before). Wetland vegetation has developed on the secondary channel, helping to stabilise the silty substrate +
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Pre works assessment included a River Hydromorphology Assessmeent (RHAT) and fisheries survey, and a flood risk assessment. The site will be monitored for several years, with the council monitoring the development of the wetland and impacts on wildfowl, Rivers Agency continuing flood risk assessment, DCAL carrying out fish stock and habitat assessment, and NIEA carry out a reRHAT on regular intervals. +
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Pre works electro fishing was complete. This is due for repeat in 2015 +
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Pre works electro fishing was undertaken at this site. Post works was carried oout in 2013. Repeat survey is not likley until 2016 +
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Pre works fishery assessment and river habitat assessment were carried out, along with photographs. Post works photographs have been taken and this will continue. One year plus fishery assessment and habitat assessment planned for 2015. +
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Pre-enhancement fish surveys have been undertaken<br>
The Environment Agency will continue to monitor this site through electric fishing surveys. +
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Pre-monitoring
Before restoration started, several indicators were monitored to see what the reference situation was for post-restoration monitoring.
'''Ecology'''
*Macrophytes - monitored qualitatively, number of species found per 500 meter channel length.
*Macro-invertebrates - species richness and abundance, and as an indicator for water quality/organic pollution (BMWP).
*Fish - biomass, fish density and species richness.
*Birds were monitored by assessing the assemblage of breeding birds and abundance.
'''Hydro-morphology'''
*Geomorphological - channel cross sections and physical habitat mapping.
*Water quality - suspended sediment concentration and concentration of nitrogen and phosphorus (measured at monthly intervals).
*Modelling of flood frequency.
'''Social-economic factors'''
*Economic benefits for six categories (water quality, amenity, fisheries, agriculture, flood defence and recreation) were calculated.
*Public perception was measured using a semi-structured questionnaire survey.
*90% of the visitors to the River Skerne in Darlington were quite or very satisfied with the restoration of the river, 15 years on from the completion of the work. ''Revisiting the River Skerne: The long-term social benefits of river rehabilitation. Åberga and Tapsell. Landscape and Urban Planning 113 (2013) 94– 103 ''
'''Post-monitoring'''
*Repetition of pre-monitoring was carried out 1 and 2 years after restoration. Due to its importance as a demonstration project, further monitoring been carried out by Master and PhD students.
*Revisiting the River Skerne: The long-term social benefits of river rehabilitation. Åberga and Tapsell. Landscape and Urban Planning 113 (2013) 94– 103
Expectations and Response:
*It was expected that the existing unpleasant park would improve in aesthetic quality and as a public recreation area. The river would feature more natural elements and dynamics.
Ecology
One year after restoration, macrophyte species richness increased above pre-restoration levels with 30%. The downstream control site did not seem to be affected by the restoration measures.
No initial changes were found in the macro-invertebrate community, but long term surveys have shown an increase in niche specific macro-invertebrate families sensitive to siltation and/or organic pollution.
The fish species richness increased with Roach (Rutilus rutilus) and Chub (Leuciscus cephalus), but the total number of caught individuals was small with only 16 fish of 4 species. The appearance of new fish species can be related to the new fish pass below Darlington. Unfortunately, several severe pollution incidents may have largely eliminated recolonizing fish populations.
Hydro-morphology
The river length was increased with 13%. Longitudinal and cross-section variability in meandered section was limited due to flood risk management requirements. However, macrophyte growth has provided some flow and habitat diversity. The constructed riffle at the upstream end has provided habitat for macro-invertebrates sensitive to fine sediments which were not found in the section prior to restoration (e.g. the freshwater limpet Ancylidae, the riffle beetle Elmidae, the net-spinning caddis fly Hydropsychidae and the blackfly larvae Simuliidae).
The new channel profile with lower banks increased the out of bank flow to a maximum of 4.5 days per year. The lowering of the floodplain itself created more water storage and the flood protection level has remained unchanged.
Social
Local residents were engaged in the project from the planning phase and post-restoration assessment showed that 52% of the local residents ‘mostly’ and 30% ‘strongly’ approved the restoration works. A majority of 64% felt that the restoration scheme had achieved its objectives and 70% of the residents thought more wildlife had been attracted to the area. Long term monitoring has shown an increased support for the restoration scheme, with increasing number of satisfied local residents.
Overall, the Skerne project was a big social success. People were engaged in the project and very positive about the outcomes. The ecological status has improved, but it is still limited by the urban environment, (e.g. fixation of the river to protect infrastructure, and pollution from industry upstream).
Pre-monitoring:
Ecology
• Macrophytes - number of species found per 500 meter channel length.
• Macro-invertebrates - species richness and abundance, and as an indicator for water quality/organic pollution (BMWP).
• Fish - biomass, density and species richness.
• Birds - the assemblage of breeding birds and abundance
Hydromorphology
• Geomorphology - channel cross sections and physical habitat mapping.
• The water quality - suspended sediment concentration, nitrogen and phosphorus.
• Modeling flood frequency.
Post- monitoring:
Repetition of pre-monitoring was carried out 1 and 2 years after restoration, as well as a public perception survey. Due to its importance as a demonstration project, further monitoring been carried out by Master and PhD students.
Expectations and results:
It was expected that the new meandering channel would provide better habitat opportunities for aquatic species and the hydromorphology and flood frequency in the floodplain would improve because of the more natural channel dimension.
Ecology
Plant species richness increased immediately after restoration. Marginal emergent plant species richness increased significantly, but submerged aquatic plants showed a less immediate effect.
The new upstream channel was quickly recolonized by macro-invertebrates. The downstream reach did not change significantly, but some more niche specific taxa were found 12 years after implementation. Two new species were found in the restored Cole, one stonefly (Leuctra geniculata) and a caddis fly (Athripsodes albifrons)
Fish biomass and density returned to pre-restoration levels, and species richness remained unchanged. However, long-term surveys have shown an overall decline in fish density at both restored and control sites, indicating impact from an external factor.
The number of breeding wetland species did not increase in the first year. The abundance of Yellow Wagtails (Motacilla flava) increased significantly. Casual inspection suggests little change after two years.
Hydromorphology
The river length was increased by 30%. The cross-sectional area was considerably smaller and less deep. The number of natural in-channel features, such as pools and riffles, increased after restoration. In the downstream section maturing trees also provide woody debris, creating habitats and flow diversity.
The restoration measures recreated a more natural flooding regime.
Social
Public perception was measured via a questionnaire and 53% of the respondents in Coleshill mostly approved with the measures while 17% strongly approved. The long-term monitoring showed that only about half of the local residents strongly (25%) or mostly (31%) approved to the river restoration project.
The restoration measures showed overall positive results for the ecological status. The downstream channel benefited greatly from the restoration measures, but the new upstream course was not fenced off from cattle and has therefore little riparian vegetation. However, due to lack of initial engagement, some local residents were unhappy with the project.
Pre-project baseline MoRPh surveys have been undertaken at Ackers Weir and at Heybarnes Recreation Ground. These Modular River Surveys will be used again to establish post-project changes.
The project has various degrees of monitoring, the lengthiest of these being the rigorous INNS (Invasive Non-Native Species) management plan in place targeting the Himalayan balsam (Impatiens glandiferula) along the banks of the river Cole. The plan predominantly targets Himalayan balsam, populations of Giant hogweed (Heracleum mantegazzianum) and Japanese knotweed (Reynoutria japonica) present on site will also be monitored.
Across all sites, Sanctus used automated continual monitoring upstream and downstream of the works. This ensures that the works were not negatively impacting the water quality, providing real time data for project partners, often showing a near immediate benefit in oxygenation levels.
Sanctus have provided 4 months of aftercare and bioremediation to materials taken from the river channel after the Ackers weir removal to improve contaminated material to form new habitats.
For the wider project, funding is being secured to create a programme of citizen science monitoring projects working with organised post-graduate and post doctorate researchers to establish monitoring across a wider range of subjects and disciplines including water quality, air quality, habitat monitoring. +
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Pre-project data +
Pre-project data +
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Pre-project data +
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