Property:Monitoring surveys and results
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M
Brown trout have already been observed spawning on the new limestone gravels. Crayfish monitoring was carried out pre works and showed a very low baseline population with only 6 individuals caught, repeat monitoring of this will be carried out along with repeat bird surveys of the site. +
R
By Intercepting run-off and trapping sediment, this scheme will help achieve better water quality preventing the loss of soil, chemicals, nutrients, and faecal organisms. A further benefit is their ability to temporarily capture water and slow down flow. his can reduce localised flooding. Improved back channel habitat that is better connected to the main river will benefit fish invertebrates and plants both in the riparian zone and amin river. +
S
By May 2013, over 1200 eels had passed through this pass.
Post Project Appraisal +
By intercepting run off and trapping sediment, all these schemes will help achieve better water quality by preventing the loss of soil, chemicals, nutrients, and faecal organisms. A further benefit is their ability to temporarily capture water and slow down flow. This can reduce localised flooding.
66 Landowners were engaged through a workshop and series of presentations to identify suitable sites, raising the profile of the effectiveness of rural SuDs schemes. 6 schemes were then taken forward and simple measures installed to reduce run-off. Some of the schemes were completed under a regulatory position statement related to the disposal of waste sediment from distilling. This ensured that regulation was proportionate to the risk, reflecting the small scale of the scheme and the overall environmental benefit. +
V
Cessation of vegetation removal led to an extended vegetation cover in the first year after implementation of the measure. Submerged vegetation and floating vegetation expanded more than riparian vegetation. +
R
Cette opération innovante sur le territoire fait l’objet
d’un suivi complet (physico-chimie, poissons, macrofaune
benthique, hydromorphologie) pour mettre en
valeur les bénéfices écologiques et servir d’exemple à
d’autres gestionnaires.
Une station de suivi est définie sur la future zone de
travaux, au niveau du pont présent entre les deux
secteurs à restaurer. L’état initial est réalisé en 2011 et le suivi post-travaux
en 2012 et en 2014. Les suivis hydromorphologiques
et hydrobiologiques seront reconduits en 2016.
L’action a des impacts positifs sur le cours d’eau qui
retrouve des écoulements diversifiés et des substrats
à granulométrie variée. Sur le secteur amont, le resserrement
du lit par la mise en place de banquettes
favorise une diversité des écoulements empêchant
ainsi le colmatage du substrat par les matières fines.
L’amélioration de l’hydromorphologie se traduit par
des vitesses, un faciès d’écoulement (radier, plat courant,
fosse) et une oxygénation proches de l’état naturel
pour ce type de cours d’eau. Ces observations
sont plus nuancées sur la partie aval, la réduction de
section étant légèrement insuffisante; du colmatage
en période de basses eaux est observé.
La survenue de crues morphogènes permettra de
suivre la capacité du cours d’eau à faire évoluer son
profil et à remobiliser les matériaux rechargés. Ces
améliorations offrent une diversité d’habitat favorable
aux espèces aquatiques comme le montrent
les résultats du suivi biologique. Cette plus grande
diversité d’habitats se traduit par une amélioration
des peuplements piscicoles (échantillonnages 2012 et
2014), avec une diminution de la densité d’espèces
de chevesne, gardon et goujon et une augmentation
et stabilisation du nombre de chabots inféodés à ce
type de cours d’eau.
La faune macro-invertébrée benthique réagit positivement
avec une diversité taxonomique plus grande
(30 taxons en 2011 contre 39 en 2012) et la colonisation
du milieu par une nouvelle famille polluosensible
(Goeridae, trichoptères).
S
Community Involvement - Engagement activities will include public consultations, practical volunteering activities like beach cleans, and tree planting, and awareness-raising through media and face-to-face contact. +
R
Counting of sea trout travelling upstream at Breuilen-Auge
has been carried out since 2001. This
monitoring is implemented under an agreement
with the owner of the dam and of the fishway.
Reproduction areas accessible to sea trout have increased
sharply, thanks to improvements works
carried out over the past 30 years. The proportion
of accessible surfaces thus increased from 15% before
1982 to 86% in 2009. The sea trout travelling
upstream monitored at the Breuil-en-Auge fishway
represented 2,500 fish in 2001 and more than 6,000
in 2008, a figure confirmed in 2009 with over 5,500
sea trout. As the monitoring station was located
upstream to many tributaries, the current Touques
stock is therefore now 10,000 sea trout, making it
not only the number one river in France for sea trout
but also one of the best in all of Europe. These very
good results are accompanied by a significant rise in
fishing tourism.
The scale of these actions and their results make the
Touques basin a benchmark for continuity in the
Seine-Normandie basin.
The Touques axis is completely open to migration,
but there are still a dozen or so more obstacles upstream
of the tributaries. There are several projects
under way. The most penalizing obstacle lies in the
middle part of the Calonne. This obstacle, devoid of
fish passes despite the regulatory obligations, neutralises
the efforts already made upstream in the
Eure département due both to the obstruction of
upstream fish migration but also damage caused by
the turbine on fish returning to the sea. +
O
Due to maintenance problems, the block structure had to be adapted. It will therefore take longer for monitoring results to come in. +
R
Due to the problems of sediment contamination stored upstream of the dam, a study
was carried out prior to the removal in order to make a diagnosis of the sediments and
their treatment. A plan is implemented to remove some of these sediments and place
them in higher areas where they were confined and stabilized by planting native
vegetation.
Two years after the removal of the dam, a monitoring plan was conducted to measure:
- Physicochemical parameters of water as temperature, dissolved oxygen,
conductivity and pH.
- Habitat availability.
- Quality of the riparian forest.
- Flora (macrophytes) and fauna (macroinvertebrates and fish) present in the
river, as well as exotic species.
The fish community in the Cofio River near the Robledo dam is: Rainbow trout
(Oncorhynchus mykiss), Iberian barbel (Luciobarbus bocagei), chub (Squalius
pyrenaicus), calandino (Squalius alburnoides) and Iberian gudgeon (Gobio lozanoi),
being Squalius alburnoides the dominant specie. All are native species of the Tajo River
Basin except from the rainbow trout that is exotic and comes from sport fishing.
Sampling points were determined both upstream and downstream from where the
dam was located. The main results of this monitoring show clear signs of recovery in
the river reach affected by the presence of the dam, with some differences between
the areas that were located upstream and downstream of the dam. +
E
Durham University undertook Archaeological Monitoring in 2017 and during the removal in 2018
Immediately post-removal WCRT have been conducting regular fixed-point photography across the site, to highlight how the river adapts and responds to being re-naturalised.
Drone-captured aerial imagery has also been recorded post-removal; once collated this can be contrasted with the footage captured pre-removal for before-and-after analysis +
R
E-CO have continuos data from detailed monitoring reaching back to 1988 on fish population (salmon and sea trout). We also have data on the invertebrate community in the river from before the hydro-power development started. There are also physio-chemical data, and continous data on discharge and water temperature. There are also data on the efficiency of the fishway, both for fish migrating up and downstream.
The data will be published in a small summary report at a later stage. +
S
Each month seven water samples are collected by the RSPB on the Leighton Reedbed and six at Hawes Water.
Each quarter this is extended to include three on Barrow Scout and two on Silverdale Moss (18 in total).
Samples are sent off for analysis. +
D
Ecological surveys completed before (2014) and after (2015 & 2016)the restoration works have shown that that invertebrate diversity has increased since the improvement works and the trout population has nearly doubled on the improved section of the beck. Engagement and involvement of the landowner has ensured that the improvements will be protected during any future maintenance works. +
A
Ecologists in the Environment Team at Buckinghamshire County Council carried out an initial assessment once the project was complete to establish what life was found in the newly created watercourse. They plan to carry this out annually to see how the river develops and establishes over time. +
M
Eel pass installed using a design that incorporating an eel trap for monitoring purposes - pass is already being used. +
S
Electric Fishing surveys to be carried out in the first summer following completion. +
R
Electrofishing and invertebrate sampling, ditch blocking and water level monitoring, wet weather surveys +
Electrofishing will be repeated post project to assess Water Framework Directive improvement for fish.
An ecosystems services assessment will be carried out post-project. This aims to assess if land productivity can be maintained, or even improved post project.
Water quality monitoring will be carried out to assess the effects of reedbeds and other measures.
A three year programme of pre-project water level monitoring is already complete and has informed the location of different habitat types as part of the overall design phase.
Ecological monitoring will continue on from the pre-project baseline, including mapping of protected, rare or locally significant species at the site.
There will be a range of opportunities for volunteering during phases two and three of the project, as well as part of the subsequent management of the site to undertake monitoring and maintenance, coordinated by the Earth Trust. +
E
En 2006 et 2009, un état initial du compartiment
physique a été réalisé : suivi de la zone d’infl uence
de l’ouvrage, de l’état du maintien des berges, de
l’estimation du risque d’érosion régressive par la
réalisation de profi ls en long et en travers. En 2007,
un suivi visuel des frayères à truite a également été
effectué en amont et aval de l’ancien seuil.
Une évaluation de l’état des berges et de la ripisylve a
également été entreprise avec le propriétaire riverain.
Après les travaux, un suivi photo est réalisé afi n de
surveiller l’évolution morphologique du site (érosion
régressive). Le suivi des frayères à truite est poursuivi
en 2009 et 2010.
L’arasement du seuil de Cros a permis de rétablir la
continuité sur un tronçon de 3,7 km de long.
Les gains au niveau de la morphologie et de la biologie
sont déjà visibles deux mois après les travaux :
le retour d’une diversité de faciès et d’écoulements
est constaté. La zone lentique en amont, auparavant
créée par l’ouvrage, a laissé la place à un secteur de
plat courant-radier sur une centaine de mètres. La
totalité des écoulements est libérée.
À l’échelle du tronçon - quelques centaines de mètres de
linéaire - une alternance de radiers-mouilles est retrouvée.
Le suivi des frayères à truite montre une recolonisation
rapide de la zone en amont de l’ancien seuil :
14 frayères fonctionnelles ont été dénombrées en
décembre 2009 alors qu’aucun substrat de ponte
n’était observé en 2007.
La hauteur résiduelle du seuil est inférieure à 30 cm
en période d’étiage. L’ouvrage est transparent lors
des périodes de migration de la truite notamment.
Sur le secteur, aucune érosion régressive n’est constatée,
ni d’effondrement de berges.
L’objectif de restauration de la continuité est atteint.
Toutefois, l’ampleur du linéaire rouvert est limitée
par la présence de deux seuils : l’un de plus de 1,5 m
de haut et situé à 2,2 km en aval, qui reste infranchissable
pour les espèces piscicoles ; l’autre, situé 1,5 km
en amont, d’une hauteur de 2 m.
Cette opération pilote pour le Sicala est l’une des
premières opérations d’arasement réalisées sur le
bassin versant. Elle a, par la suite, servi d’exemple
pour quatre autres réalisations d’effacements d’ouvrages
sur le bassin.
Dans le cadre du CRE, d’autres opérations de
restauration de la continuité écologique ont été mises
en œuvre : trois autres arasements ont été réalisés en amont de la commune de Dunières, puis un autre sur le
Gournier, affl uent en rive droite de la Dunière. Le Sicala
a également procédé au remplacement d’un passage
busé sur un affl uent (le Charrerogne) par un pont
cadre, décloisonnant ainsi totalement l’affl uent. Enfi n,
deux autres ouvrages ont bénéfi cié de l’installation
d’une passe à poissons au niveau de la commune de
Dunières (lieu-dits : Berthollet) et boulodrome.