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A lost river has returned to the Somerset countryside more than 60 years after it dried up.
The unnamed tributary of the River Chew will contain water for the first time since 1956, when a dam was installed and the valley was flooded to form the Chew Valley Lake reservoir.
The river ecosystem eventually dried up and died, taking with it an ecological corridor used by aquatic creatures since the last ice age.
But the half-a-kilometre stretch of river has now been restored and will provide habitats for wildlife including herons, otters and fish.
The work comes as part of a restoration project by Bristol Water and Bristol Avon Rivers Trust (BART).
Signs of ancient rivers on Mars revealed in new imagesShow all 13 1 /13Signs of ancient rivers on Mars revealed in new images Signs of ancient rivers on Mars revealed in new images Perspective view of ancient river valley network on Mars These images taken by the European Space Agency’s Mars Express satellite show the marks that an ancient network of rivers have left on the planet’s surface.
ESA/DLR/FU Berlin
Signs of ancient rivers on Mars revealed in new images Ancient river valley network on Mars The valleys formed as they would on earth, with a strong flow of water carving its way through the landscape. What is less clear is where the water came from. Due to a lack of knowledge about the past climate of Mars, scientists can not tell whether it came from groundwater, precipitation, melting glaciers or something unheard of.
ESA/DLR/FU Berlin
Signs of ancient rivers on Mars revealed in new images Ancient river valley network on Mars This colour-coded topographic view shows the relative heights of the terrain in and around the network of dried-up valleys on Mars. Lower parts of the surface are shown in blues and purples, while higher altitudes show up in whites, yellows, and reds, as indicated on the scale to the top right.
ESA/DLR/FU Berlin
Signs of ancient rivers on Mars revealed in new images Ancient river valley network on Mars This image shows the landscape in and around a network of dried-up valleys on Mars. The region outlined by the bold white box indicates the area photographed by the Mars Express.
NASA MGS MOLA Science Team/FU Berlin
Signs of ancient rivers on Mars revealed in new images Eberswalde crater delta This dried-up ancient river delta once carried liquid water across the surface of Mars. The photographed area is 31 x 7.5km. Released on February 4 2019.
ESA/Roscosmos/CaSSIS
Signs of ancient rivers on Mars revealed in new images Eberswalde crater delta Eberswalde crater formed more than 3.7 billion years ago. The rim of the crater is only intact in the north-eastern part, the rest has been buried by debris from the nearby, more recently formed Holden crater.
ESA/DLR/FU Berlin
Signs of ancient rivers on Mars revealed in new images Eberswalde crater delta In the left of the image is the Holden crater, which is 140km across. To the right is the Eberswalde crater, which is 65km across.
ESA/DLR/FU Berlin
Signs of ancient rivers on Mars revealed in new images Korolev crater A perspective view of the Korolev crater, an 82-kilometre-across crater filled with ice found in the northern lowlands of Mars. Taken by the European Space Agency's Mars Express satellite.
ESA/DLR/FU Berlin
Signs of ancient rivers on Mars revealed in new images Korolev crater The Korolev crater, an 82-kilometre-across crater filled with ice found in the northern lowlands of Mars. Taken by the European Space Agency's Mars Express satellite.
ESA/DLR/FU Berlin
Signs of ancient rivers on Mars revealed in new images Korolev crater DisThis colour-coded topographic view shows the relative heights of the terrain in and around Korolev crater, an ice-filled crater in the northern lowlands of Mars. Lower parts of the surface are shown in blues and purples, while higher-altitude regions show up in whites, browns, and reds, as indicated on the scale to the top right. The crater’s thick deposit of ice can be seen at the centre of the frame. Released December 20 2018
ESA/DLR/FU Berlin
Signs of ancient rivers on Mars revealed in new images Water buried under the south pole of Mars ESA’s Mars Express has used radar signals bounced through underground layers of ice to identify a pond of water buried below the surface.
ESA/NASA/JPL/ASI/University of Rome
Signs of ancient rivers on Mars revealed in new images Water buried under the south pole of Mars The brighttop line represents the icy surface of Mars in this region. The south polar layered deposits – layers of ice and dust – are seen to a depth of about 1.5 km. Below is a base layer that in some areas is brighter than the surface reflections, highlighted in blue, while in other places is rather diffuse. The details of the reflected signals from the base layer yield properties that correspond to liquid water.
ESA/NASA/JPL/ASI/University of Rome
Signs of ancient rivers on Mars revealed in new images Water buried under the south pole of Mars The 200km square study area is shown in the left image and the right image shows the radar footprints on the surface of Mars.
ESA/NASA/JPL/ASI/University of Rome
Matthew Pitts, catchment strategy manager at Bristol Water, said: “It is the first time the river has been permanently re-wetted since the 1950s and will offer a considerable environmental benefit for the downstream river.”
He added that he hoped to see the stream teeming with mayflies, damselflies and dragonflies.
Some residents living in the area have been apprehensive about the river extension following a devastating flood in 1968 which killed seven people.
During a storm which saw five inches of rain fall within just 24 hours, the waters rose so high that it was feared the dam wall would burst.
Bridges were washed away as torrents of water poured down the Chew Valley, flooding buildings and sweeping away cars.
However Mr Pitts said his team had carried out modelling to reassure people the project would not increase the flood risk.
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