Property:Lessons learnt
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U
Head waters should not be discounted as a place to look to restore even when restoration seems unfeasible due to current condition. The benefits can be significant.
When lowering floodplains, considering how the material can be landscaped on site and used for other benefits e.g., wildflower habitats but understanding that the site to look a bit stark whilst this establishes.
The value of an experienced site supervisor and a skilled contractor cannot be underestimated.
Confidence in the contractor's experience enabled them free reign to be creative within the constraints of the given inset floodplain parameters, and to observe and work with the river gives a more organic approach (regular site checks ensure all going to plan and landowner completely happy).
Concise and transparent communication with landowner to build trust is key, enabling a more flexible approach on the broader principles of work as they were set out, facilitating a more natural approach from the contractors on the ground. +
A
Improvement of structural operability enables review of operation regimes to minimise the requirement for further improvement works. Whilst replacement of existing structures is not a sustainable measure, the operating regime that follows increases the long term condition of the river and structure. +
W
In August 2017 the flood resilience of the project was immediately demonstrated when heavy overnight rain caused the river to rise and temporarily flood the berms. Soon after completion chub were observed on the fresh
gravel bed and in winter 2017/18 brown trout redds (spawning scrapes) were located. The access berm was an immediate success and provided the venue for river studies at the World Rivers Day event in September 2017. +
T
In our opinion the most valuable lesson learnt is to work with the landowner and be open and honest from the start. By listening to the landowner it helps to understand where the most suitable intervention may be on the watercourse. This is then followed by partner working, by having multiple partners working together it allows an increase in scale of delivery.
Right improvement in the right place. We have seen other individual projects being delivered which do not have the support of neighbouring landowners, and whilst this may return site specific benefits it can often be at the detriment of the wider catchment, as the works can't be replicated close by to build upon the benefits of the initial project. +
L
In progress +
E
In summary and according to Pallarés and Martín-Vide (2015), ecogeomorphic activation of the 7-km long study reach may
be optimised by the release of 12 m3
/s flooding events; a peak rate
higher than the present legally defined rate of 8.4 m3
/s. Suspended and
bedload transports are particularly relevant at rates of 8 m3
/s and
higher; especially in the sampling sites closer to the dam toe. However,
both types of transport could be primarily associated with in-thechannel
sources, which could be progressively hampered by the existing
lack of upstream inputs. Habitat conditions exhibited a limited positive
trend with increasing discharge. On the basis of these findings, the authors suggested that larger peak discharges could be desirable, but
would also require the implementation of measures for increasing
sediment discharge from the dam in order to avoid progressive incision
and further sediment shortages along the study reach. +
M
Increased knowledge for farming community in the area and less cattle poaching and phosphate inputs.
Sharing of knowledge for best practice and innovative solutions has been useful across the catchment. +
N
Involving communities in river restoration projects not only improves understanding and ensures long term support for projects but volunteers can help keep project costs down, enabling us to achieve more limited budgets. +
P
It has worked well to do this project in two phases, firstly with the addition of the wood and secondly with the gravel. Particularly where living willow has been used, it will allow the woody material to establish before trapping the gravel as it moves downstream over time.
The use of natural wood found on site and the placement of gravel at a single point with good access have proved very cost effective compared to a constructed riffle approach.
If safe to do so, gravel is best added in high flows to avoid the requirement for people in the channel to rake it flat. The high flows will naturally and quickly sort the gravel into position. The gravel used was 5 – 20mm size range; in future a 20 – 40mm component should also be included to match the naturally-occurring size range in the Upper Witham. +
I
It is considered that the
proposal of removal in
different stage is
adequate and it seems
correct to apply this
methodology in actions of
similar characteristics. +
H
It is impossible to achievement multiple benefits in a hollistic approach project without the support and commitment of partners, local land owners and local residents. We have only managed to achieve this through dedicating time to bringing the right people together and explaining clearly our aims and overlapping benefits. Only then can efective work on the ground begin. It is vital to consider legacy and exit-strategy right from the beginning. Working at the sub-catchment scale cannot be considered in the short-term. Management and maintenance of interventions must be planned for and bought into within the community. +
B
It took some time for the measures to be implemented, but eventually they were carried out as planned. It will take time for the expected ecological improvements to happen. The new pool and running water areas will undergo recolonization and adaptation.
The effect of such measures can be difficult to measure, but there is little doubt that more stable water flow, larger and deeper pools and concentration of water flow will benefit the ecosystems in and around the rivers.
Thus far, the rivers have only achieved moderate ecology potential and further measures are needed to raise their ecological status further. As the water bodies are HMWBs, they will never reach full good ecological status, but with further restoration measures Mykleelva and Vanebuelva can achieve good ecological potential.
The improvement works will require maintenance as their “life expectancy” depends on the amount of river sediment transport and the frequency and magnitude of the floods. +
N
It was apparent that the bottom box may still cause problems for ascending fish due to the distance between the pool and the bottom of the box presented by an apron extending out some 1.05m under the water which could restrict fish from jumping into the box under certain flow conditions. Further work will investigate options to alleviate any problems associated with this part of the structure. +
C
It was difficult to identify a cost-effective and reliable method of determining the original bed level beneath significant amount of stored sediment upstream of the weir. The final decision was to remove the sediment in a careful and 'staged' manner, ensuring that hydromorphological expertise was on site to determine the point at which the original bed level was reached. This made it difficult to estimate clear costs of sediment disposal, but estimates proved relatively reliable. +
B
Its a stopping over site for many migratory passerines and also breeding ground, the conservation of this habitat is essential for monitoring and maintain the populations of these species +
P
July 2011: Wetland working very well as partly groundwater fed. The presence of contaminated soil has limited the aspirations of modifying the river bank. +
D
Landowner buy in and suitable catchment management is essential, and there is a good uptake of the Welsh Government's Glasdir Agri-Environment scheme in this small catchment.
Successful captive rearing of juvenile mussels at the NRW Aquaculture Unit at Cynrig is considered to be an important future development to secure the future of the species.
Due to the sensitive species present in this river, a spread out one step at a time approach to restoration has been appropriate. +
C
Création d’un bras de contournement de plusieurs étangs sur le Fliez et restauration du marais de Contes +
Le point faible de cette action reste la présence de
rejets domestiques vers ces milieux aquatiques.
Le point fort de cette action est la conciliation des
différentes activités de loisirs (pêche, chasse) avec les
enjeux environnementaux.
Cette restauration du Fliez s’intègre dans un ambitieux
programme de reconquête du marais de
Contes, qui explique le coût élevé de l’action. Les
trois quarts du budget sont consacrés à la restauration
des habitats typiques du marais et des étangs
associés +
S
Learning from previous experiences of restoring other sites led the project team away from a prescriptive design solution. Instead they relied on the skills and expertise of the North Norfolk Operations Field Team, to determine the finer detail based on how the river reacts to restoration features as they were constructed. The team were able to incorporate locally available materials such as timber from selective tree management, and re-use spoil banks from historical dredging of the channel.
This flexible approach used fewer resources and saves money by reducing the amount of material needing to be imported. It was a big advantage in Sculthorpe, where ground conditions for machine access were challenging. +
L
Learning lessons from the earlier GAAFFS work, willow logs were was not used in the subsequent phase of enhancement work. Instead logs, branches and brushwood generated by the management of other riverside tree
and shrub species were used to create a variety of structures to protect vulnerable banks from erosion, narrow the channel and trap suspended fine sediment. +