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The San Marcos weir is located in the city of León. The weir has been operating during
the last 50 years, accumulating large amounts of upstream sediments and generating a
strong incision downstream of the dam, which requires a specific management.
Works: partial demolition of the weir, decreasing its height by about 2.5 meters. Its
complete demolition was not viable because it is a danger for the bridge sited
upstream the weir, which has a high historical and cultural value. A fish pass was also
installed to facilitate the movement of the fish species in the river. The process of
demolition has to take care of the bridge placed upstream, so that the cost of the
works became more expensive.
Benefits:
- Decreased risk of flooding in the city of León. With the adopted solution, the danger
of flooding decreases considerably, regarding the previous situation in which the river
would overflow for a return period of 131 years, with the projected solution, there is
no risk of overflow for a 494 m3
/s flow, corresponding to the period of return of 500
years.
- The materials removed from the weir were used to fill the pool produced
downstream the weir (approximately 6 meters deep), diminishing the erosion of the
river bed (600m3 removed from which they used 500m3 to fill the pool).
- The longitudinal connectivity was enhanced by the construction of a fish pass,
improving the potential habitat for native fish species such as the Brown trout (Salmo
trutta) and the Northern Iberian spined-loach (Cobitis calderoni).
- Local populations are usually against the use of public funding to remove dams. This
removal action supposes a measure of awareness for the population of the city of
León.
- Increasing awareness of local people about the natural conditions of a river. +
R
The Saumuehle stream is a 1,5 Km tributary of the Petersbach river, located in the Petite Pierre Nord forest. It is a firs class fish stream.
In 1980, the Saumuehle pond (12000 m2) was created for recreational fishing. The pond cause warming waters downstream and the weir is an obstacle to ecological continuity.
After a few years, the dam, made with soil from the excavation of the pond, lost its seal and the water level had dropped, leading to a gradual filling of the pond.
Under an Interreg project which aims to improve the condition of the river in the forest, this site was chosen as a pilot site.
The work takes place in several phases. At first, the pond is drained in order to remove the drain boards
After conducting a fishing rescue and temporary diversion of the river to a side ditch, materials of the dam are moved on the edge of the pond. Then, reprofiling sloping instead of the dam is made. A lateral pond is created to hold the presence of amphibians observed on the site. +
The Seaton catchment is heavily impacted by historic mining activity throughout its entire length, but especially in the upper reaches around South Caradon mine. The mine is located on the South Eastern edge of Bodmin Moor in South East Cornwall. It is cut through by the River Seaton which is fed by groundwater as well as surface runoff during heavy rain events. Ore processing at South Caradon mine started in 1838, at which time the mine covered most of the south side of Caradon Hill, and finished in 1890. When South Caradon finally closed it left miners with no prospects of work anywhere else in the Duchy. Many went to England to find work in factories or coal mines, but large numbers emigrated to work metal mines all around the world.
From the remains on the site and documented history, it is known that the processing of material from the mine shafts was carried out within the River Seaton valley. River water from the Seaton was used in the separation process, and waste water with a high concentration of metal solutes, sand, and silt-sized particles, was discharged directly into the River Seaton. Processing of Cu bearing ore at South Caradon mine involved the heating, pulverizing and dissolving of metals and their compounds, resulting in release of Cu and Zn into the surrounding environment. The legacy of these processes is a proliferation of tips, disused shafts and 3 adit discharges which between them contribute high levels of Zinc, Copper and Cadmium to the river.
When water quality and flow data are combined, it is evident that the most important sources of Cu, Cd and Zn contamination in the River Seaton are Jopes Adit, and the ‘3 Adit Streams’ . Although the 3 Adit Streams discharge from beneath a rock tip, the chemistry results indicate that the 3 Adit Streams and Jopes Adit discharges are related in terms of source. Tip run-off is an additional significant source of Cu, Cd and Zn entering the main stream, particularly in prolonged heavy rain conditions. The site is listed on the MINING WASTE DIRECTIVE INVENTORY (http://apps.environment-agency.gov.uk/wiyby/139297.aspx) since the wastes cause more than 500 metres of the river to be polluted.
Most of the mine site is designated as a Site of Special Scientific Interest (SSSI) since the high metal concentrations in the soil support specialised flora of rare mosses and liverworts. This is one of two sites in the world where the Cornish path-moss occurs. The Caradon Mining District is part of the CORNISH MINING WORLD HERITAGE site (http://www.cornish-mining.org.uk/areas-places-activities/caradon-mining-district).
IMPACT OF THE JOPES ADIT DISCHARGE Length of watercourse affected - 17km. Average metal concentration in the mine water: Zinc 510ug/l; Copper 1180ug/l; Cadmium 1.5ug/l. Average flow - 56 l/sec. Load of Zinc discharged per day - 2.5 kg. Load of Copper discharged per day - 5.8 kg. Water body ecological status Poor.
WFD Compliance The whole river length from headwaters to tidal limit is non-compliant with Water Framework Directive Standards for copper. For zinc and cadmium at least 4.5km of river are non-compliant with the WFD standards. The WFD monitoring site at Hendra Bridge is below all the main impacts and most recent mean levels here are: Cd 0.185ug/l (EQS = 0.08); Cu 75ug/l (EQS =1); Zn 67ug/l (EQS = 8).
All these are non-compliant with copper being approximately 75 times the standard for good status, whilst cadmium (a Priority Hazardous Substance under the WFD) concentrations are double the amount needed to achieve good status.
BENEFITS OF REMEDIATION The River Seaton will be protected from a major pollution source. Contribute towards achieving Good Ecological and Chemical status. 912 kg of Zinc and 2,100 kg of Copper would be prevented from entering the River Seaton every year.
The Environment Agency is working with the Coal Authority to develop remedial options to address the pollution and return the river to good status. At the current time (August 2014), we are not able to say when we will be able to start work on cleaning up the river.
E
The Sectorial Plan of Environmental Flows (ACA, 2005) requires the
annual release of one effective discharge from the dam (the Llosa del Cavall Dam), in order to
protect or improve the “dynamic equilibrium of the river.” This
controlled release lasts 24 h, and its seasonality is linked to the natural
period of occurrence of ordinary floods in the river. Presently, the Plan
defines a peak discharge of 8.4 m3
/s for the controlled flood. Ramping
rates are defined as follows (t indicates 1-h time gaps):
• Rising limb: Qt+1 (maximum) = 1.8Qt
• Recession limb: Qt+1 (minimum) = 0.7Qt
To study the adequacy of this value, the Catalan Water Agency (with
support from the Technical University of Catalonia) decided to comparatively
monitor in 2015 the effects of three different peak flows that
were lower than the 2-year recurrence flood (i.e., 4, 8, and 12 m3
/s;
Pallarés and Martín-Vide, 2015; Fig. 3). The first and smaller flood was
released between March 3 and 4, the second was released between April
13 and 15, and the third and larger was released between June 15 and
16. The base environmental flow released from the dam is commonly
around 1.5 m3
/s. +
R
The Severn Estuary foreshore has international importance, reflected by the following designations: Site of Special Scientific Interest (SSSI), Special Protection Area (SPA), possible Special Area of Conservation (pSAC) and Ramsar. The site itself is located seaward of the Wentlooge Sea Defences, where the upper, vegetated saltmarsh is referred to as the 'wharf' and the lower unvegetated foreshore as the 'mudflats'.
The Wentlooge Sea Defences (Map 1) protect an area of low-lying land, of which approximately 32km2 lies below mean high water springs (MHWS). The wharf acts as part of the sea defence by reducing the incident wave energy on the embankments themselves.
Study of the foreshore highlighted that the wharf had been eroding locally at a fairly constant rate over a long period. In 2003, pockets of erosion were in close proximity to the flood defence embankment and as such continued erosion was predicted to undermine the embankment by the year 2008. As an immediate mitigation against further erosion of the wharf, thus protecting the defences, it was decided to use harder, more traditional engineering in the form of blockstone and rip-rap. As a longer term strategy, polder were used in an effort to regenerate the mudflats and increase protection to the wharf scarp.
The works that were carried out have effectively stopped/slowed the erosion of the wharf, thus:
• maintaining the ecologically important land
• preventing the undermining of the defences and maintaining their function
• protecting ~30km2 of agricultural land, business and numerous communities within the Wentlooge Levels +
S
The Sherborne Windrush Restoration Project is a partnership project that will use CRF funds to improve the River Windrush and the Sherborne Brook in the Sherborne area of Gloucestershire.
The river suffers from a degraded habitat aris-ing from insensitive dredging which has removed river bed gravels and built up banks causing a disconnect from the water meadows as well as suppressing in stream habitat varia-tion. There are also problems caused by dif-fuse agricultural pollution and areas of over sharing. These issues are preventing this stretch of water from meeting the required standards under the Water Framework Directive (WFD). This project will build on the work already completed by addressing the following issues: inadequate levels of fish spawning gravels; lack of in-stream habitat variation; pollution from agricultural run off; poaching of the banks by cattle; lack of hydrological connectivity with the flood plain; over shading by streamside vegetation. +
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The Sienne is mentioned in Lists 1 and 2 of Article L. 214-17 of the Environmental code for migratory fish, including Atlantic salmon, sea lampreys, river lampreys, brown trout, sea trout and eels.
Approximately 40 transversal structures exist along the river, representing one structure every two kilometres on average. Most of these structures serve no economic purpose and half are in ruins.
The Ver mill, built centuries ago, had not served an economic purpose for decades. The mill weir, 1.7 metres high, was in very poor condition.
In 2009, the mill was purchased by a new owner. The State services and the Water agency explained to the new owner the situation with the structure and the issues at hand in the sector. The owner accepted the removal of the structure given the safety issues (the dilapidated condition) as well as the regulatory and economic context (the publication of a new river classification in 2012, taking into account new species in the design of fish passes (Art. L. 214-17 of the Environmental code). The owner relinquished his water rights in November 2010.
The Ver mill weir was completely removed. The rubble of the stone weir was used on the right bank to create groynes to centre flood waters. The project included maintenance of the riparian vegetation upstream. A nearby pond was restored to replace the mill pond that had been used by the local fire department. Finally, fences and watering points were set up on neighbouring lands. +
The Sommière du Moulin rivulet and the Verne Fendue rivulet are temporary tributaries of the upstream Clauge. The River Clauge flows over 35 kilometres before joining the River Doubs. For 70% of its length, it crosses the Forêt de Chaux. The forest’s hydrographic network includes 460 km of streams, only a tenth of which are permanently fed.
In 1950, foresters started draining, straightening and cleaning out around a hundred kilometres of rivers in the forest of Chaux, with a view to cleaning up these plots.
The rapid removal of high water levels then caused major regressive erosion. The streams cut deeper channels and the river habitats became homogenised, leading to reduced crayfish populations. Since the 1970s, the drying out of the river stream system has been observed and the limits at which the flows are permanent have moved several hundred metres downstream and has been observed a tendency towards dieback, especially in oak trees.
Part of the Chaux forest is included in the Natura 2000 site. This site was chosen for a project to reconstitute water reserves.
The original meandering bed was restored by eliminating the straight bed via a series of watertight “plugs”. At the same time, a narrow, shallow and sinuous furrow was dug in order to initiate the meandering course, which will only be completed when the original course and the connection with the downstream meander are no longer visible. This “groove” only acts as a guide in order to channel the flow away from the straight channel: therefore, it is essential for it to be smaller than the supposed dimensions of the meandering bed. In the medium term, the straight bed segments and remaining ditches should be partially obliterated by the accumulation of organic matter (woody debris and leaves). In order to encourage this natural process, the removal of debris, jams and blockages from the stream beds, and even any maintenance of the riverside vegetation, are prohibited. +
C
The Soto of Campollano is downstream Carcastillo town. The work area was located on the left Aragon River bank, where the little tributary Abejar ravine flows into the Aragon River. The tributary of Aragon is surrounded in its mouth by a river forest of 32.6 has called Soto de Campollano represented by the habitat 92AO in a good conservation status. In the riversides there are areas of grasslands.
The main objective of this project is to increase the quality of habitat in Community Interest Areas, with special attention to European mink (Mustela lutreola). There are other secondary objectives: Creating new habitats for otter (Lutra lutra) and turtle (Emys orbicularis); quality improvement of habitats 92A0 (willow and black poplar plantation) and 3150.
The project includes the creation of some new habitats that affect animals and plants. New bio-engineering techniques are used to develop and help these riparian communities.
The project was presented by the “Environmental Management for Reintroduction and Repopulation in Navarre” in cooperation with the Government of Navarre’s Environment, Land and Housing Department. It was part of a LIFE project.
Construction of three small ponds connected through small meandering channels. +
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The Soto of El Estajado has an area of 64 hectares. The main surface was occupied by old black poplar plantations and little bad conserved areas of Community Interest Areas 92A0 and 92D0. The area was used for inappropriate cattle. The actuation area limits with an important community of European mink (Mustela lutreola). The actuations are aimed at preserving this protected species.
The main objective of this project is to increase the quality of habitat in Community Interest Areas, with special attention to European mink (Mustela lutreola). There are other secondary objectives: Creating new habitats for otter (Lutra lutra) and turtle (Emys orbicularis); quality improvement of habitats 92A0 (willow and black poplar plantation) and 92D0 (tamarisk plantation); spatial planning for cattle; restore the natural riparian vegetation in Aragon River.
The project has a total budget of 152.948,34€ and is financed by GERVE-LIFE project, INTERREG GIRE project, "Gestión Ambiental, Viveros y Repoblaciones de Navarra, S.A." and Government of Navarre.
Construction new habitats for otter (Lutra lutra) and European turtle (Emys orbicularis). +
S
The Sowe Valley Project is a community based river restoration project, working with local communities along an 8 1/2 mile stretch of the River Sowe in Coventry to help improve it for both people and wildlife.
The project, with local volunteers deliver the following work along the valley:
1) himalayan balsam control 2) mink monitoring 3) removal of polluting items from the channel 4) bank side vegetation work to improve light and shade levels in the river 5) bank side planting of native species.
The project has at least 4 volunteer days per month - see the website for full details.
The Sowe Valley project has also supported the formation of the Friends of Sowe Valley, a voluntary group set up to keep the river conservation work going after the project funding ends.
The Sowe Valley Project has received £211,512 of funding from Natural England’s Access to Nature Programme, funded by £25m from the Big Lottery Fund’s Changing Space programme. The project has also received funding from the Environment Agency, BKW housing consortium and kind donations from Warwickshire Wildlife Trust members. It is also supported by Coventry City Council. +
The Springendalse beek is a tributary of the Tilligterbeek, which in turn is a tributary of the river Dinkel. The stream flows through a largely natural area. To restore its ecological value and retain more water, the incised bed was raised to a level that was closer to its previous state. +
The St Austell Bay Resilient Regeneration Project (StARR) project on the south coast of Cornwall is in developmental stages. It is relying on European Structural Investment Funds (ESIF) and Flood Defence Grant in Aid along with Defra Natural Flood Management (NFM) budget to deliver all aspects of the project. Classic flood defences are no longer the sole solution for protection of properties in this catchment. The project team is investigating catchment interventions such as: floodplain connection; slope interception by tree planting and hedgerow construction; potential storage in disused quarries. in town options include: blue–green infrastructure; overland flow routes; sustainable urban drainage (SUDS); removal of historic infill; reconnection of floodplains. The project aims to provide property and business flood protection through: 7km of river restoration; 30ha of habitat creation and restoration; storage in the catchment equivalent to 400 Olympic-sized swimming pools; regeneration of the community through landscape scale restoration and links to the tourist industry. Links to existing environmental and social projects are ongoing and planned in the catchment such as: Heritage Lottery Fund Wet Grassland bid; Luxulyan World Heritage Site improvement project; protection of historic buildings 'at risk' +
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The Steinbaechlein is a 14.5 kilometers long secondary arm of the Doller, the latter having a mainly agricultural 215 km2 wide watershed.
In the XIX century, a 400 long meander of the Steinbaechlein was cut in order to provide water to a chemical factory.
Following the dismantling of the factory and in the framework of a new business and residential development, the river was returned to its old bed. The work was motivated by the need to increase the available surface for a commercial building and the will to get the river away from polluted soil.
The new bed was excavated in the wasteland that had developed in place of the former course of the river. Diversified cross sections and widths were established and the profile was fixed by two sills; helophytes were planted in the banks and in the riverbed along almost all the restored stretch. On the left side of the river a wetland was created, to be used as flood retention area. +
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The Sussex River Ouse near Slaugham, West Sussex has historically been managed for navigation. These works have straightened the channel, increasing the width and depth in many places.
The Spring meadow site is on the north eastern bank of the river at Sheffield Park, within the High Weald Area of Outstanding Natural Beauty (AONB). The site was acquired by the current landowner to increase wildlife value in the area. Since conception in 2010, works on site were finished in 16 weeks and the project was completed in 2012. Initially it had been hoped to complete works in 8 weeks, however heavy rainfall caused a relatively short delay.
The Sheffield Park Meanders project involved the reinstatement of the historic meandering course of the Ouse at spring meadow to achieve the following aims:
• Reinstate the historic course of the river through the re-excavation of the visible meander. The creation of a meandering channel allows a greater diversity of habitats to develop, specifically for multiple fish species.
• Reduce flood risk by creating a longer meandering channel length, which slows the flow of water heading downstream. At the same time the new bank profiling aimed to encourage natural functioning of the floodplain.
• The incorporation of a low flow channel which maintains sufficient water depth for fish migration in all flow conditions.
• Restoration of existing wet meadow habitats at the site and creation of new woodland areas.
Initially a 20 meter trial area was excavated, allowing adjustments to be made on expert on site recommendation. Banks were roughened up with a toothed bucket to ensure an undulating bank profile. Spoil from excavation was spread across a railway embankment close by to reduce the cost of disposal.
The project was named the Professional category winner at the annual Wild Trout Trust (WTT) Conservation Awards 2013. The panel comprised two experts, Paul Gaskell (WTT) and Dr. Jenny Mant from the River Restoration Centre.
The project is one of thirteen projects within the Middle Ouse Restoration of Physical Habitats (MORPH) project; led by the Environment Agency in partnership with the Ouse & Adur Rivers Trust (OART) & supported by Royal HaskoningDHV (design, engineering and environmental consultancy services) and C A Blackwell (contractor for the implementation works). Each of these projects is being considered individually but also in terms of how they will work in conjunction with each other to improve the diversity of the river and reduce flood risk.
Several details were built into the design to meet the site specific requirements. A ford was constructed to give access to a newly created island area in the centre of the channel. Woody material was added to the new channel at five locations to encourage flow diversity and provide the channel with some shade. The existing channel and new meandering course are joined via a bund constructed at the upstream confluence of the two channels. At normal flow levels this directs all the flow down the mender, leaving the old course as a backwater. In times of flood the bund can be overtopped, allowing water to flow down both channels, increasing local flood capacity.
The land surrounding the site is in Higher Level Stewardship scheme for floodplain hay meadow. The island at the centre of the site was no longer manageable as a hay meadow, therefore a Forestry Commission Woodland Creation Grant was approved to create 1.5Ha of floodplain woodland. This area would slow the flow of flood waters, help to trap sediment and increase biodiversity of the site.
Promotion of the project included coverage on BBC South East today programme, local papers and area group websites.
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The Taarlosche Diep is a small stream that is part of the Drentsche Aa water body. It has retained most of its original meandering character, although parts of the stream system have been straightened and reinforced. The mowing regime in the Taarlosche Diep was adapted to meet WFD goals and other ecological goals. A maintenance plan is currently being developed.
See also: http://www.rtvdrenthe.nl/nieuws/168154/Waterschap-verhoogt-beken-Drentsche-Aa-gebied-Omliggende-natuur-kan-zo-natter-blijven +
The Tall River is a main tributary of the River Blackwater, flowing through Co. Armagh. It is a slow flowing, low energy river within an agricultural catchment. The river had been subject to an arterial drainage scheme in the 1960s, which deepened and widened the river as well as disconnecting it from its floodplain. The 1.2km Tall River scheme was the first project within Northern Ireland to address the specific need to enhance the riverine environment, rather than being attached to a larger flood prevention scheme. Works could only be carried out in-channel and on the National Trust owned right bank due to landowner restrictions.
The aim of the protect was to create shallow slack-water habitat through the creation of bays. These would provide shelter for fish fry and invertebrates during high flows and aimed to increase macrophyte diversity within the reach. Stone cascades were also installed to direct flow away from potentially erodable banks.
A repeat RCS carried out two years post works indicated an increase in emergent vegetation and macrophyte diversity. The bays are inundated at high flows, acting as a fish refuge, however due to siltation these may be becoming too shallow. Following the creation of stone cascades greater flow variation has been ovserved. The success of the bays appears to depend on the presence, or otherwise, of a structure deflecting water into them.
If the project was to be carried out again more consideration should be given to the location of the bays within the overall flow regime or alternatively structures that would maintain flows into the bay should be included in the design.
Plus, part of a wider scheme developing footpath access along the river. +
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The Tees Estuary is one of the most heavily modified and developed estuaries in the UK, with less than 10% of the original intertidal habitats remaining. From 1740, large areas of saltmarsh have been enclosed to form freshwater grazing marsh. However, the industrialisation and systematic land take between 1830 and 1970s has resulted in significant habitat loss. It is estimated that the Tees Estuary has lost over two thirds of its intertidal habitat through waste disposal and infilling over the many years of modification, some 3,000ha, or 30km2.
The Greatham Marsh Restoration project is centred on the restoration of intertidal habitat on the low-lying agricultural land near Greatham Village. Historically, the village was on the edge of the marshes but is now inland from the remaining intertidal areas.
The land is currently protected by flood banks constructed in the 18th century and a tidal structure with tidal flaps constructed in 1980 by the former water authority. The alignment of Greatham Beck was rationalised in approximately 1981 when the original meandering tributary was infilled.
The tidal structure was constructed under a licence that expires on 30 November 2029. A condition of the licence stipulates that on the expiry of the Licence, the structure is removed and riverbanks and foreshore reinstated.
This alone would not restore the full extent of natural processes and habitats. The oversized Greatham Beck would become a deep tidal creek and the floodplain would be inundated for long periods of time as a result of historic embankments and ineffective drainage.
So the Project intends to restore the former meandering channel of Greatham Beck and the network of tidal creeks within the floodplain. Areas of higher land within the field parcel are proposed to be managed as grasslands for conservation purposes. Habitats would be allowed to migrate inland as sea level rises.
The project contributes to achievement of WFD objectives by implementing targets for WFD protected sites found within the conservation objectives of the SPA, and mitigation measures for the Tees Estuary water body.
T
The Teglverksdammen is a reach of the stream Hovinbekken which opened in 2015. The project was initiated to improve the water quality downstream, as the downstream area (Ensjø) was to be transformed from an industrialized area to a new residential area. The Tegiverksdammen consists of a stretch of riffles and pools, followed by a large pond (called Teglverksdammen), a short river stretch (to become a wetland) and a final pond for sedimentation. After the final pond (Grensedammen), the river flows into the Ensjø area. The water in this system originates from an 800 m culvert, and part of the flow is still directed to the original culvert, to prevent flooding of the system. The water quality is typical of urban streams, with high nutrient levels and organic load. +
The Test and Itchen Invasive Non Native Species (INNS) Project is an ambitious multi-year partnership project aiming to reduce the impact of invasive non native species on the precious native wildlife and habitats of the Test and Itchen river catchments.
https://storymaps.arcgis.com/stories/176a464b691a44158f626f3594127a4d
The project was developed when multiple stakeholders and members of the Test and Itchen Catchment Partnership raised concerns around the growing threat posed by invasive species on the integrity of these globally rare chalk streams. The first phase of the project was conducted by the Hampshire and Isle of Wight Wildlife Trust, collecting data and pooling resources to determine the current understanding of invasive non native species distribution in the catchments. Partners agreed a multi-stakeholder, collaborative, catchment scale approach was required to tackle the threat posed by invasive non native species and improve the health of our rivers. +