Nature River Mel We continue to be very concerned about the lack of water in the river. Since our last article the situation has become much worse, with large sections of the river being completely dry. The Mel is a springfed chalk stream, with the main source being at Melbourn Bury where springs rise in the lake at the front of the house. As we write this in January, the lake in front of Melbourn Bury is completely dry, as is the river through Stockbridge Meadows and Dolphin Lane. A second tributary, which flows round the corner of Station Road to join the main river in front of Sheene Mill, dried up during December. We have been asked why the river upstream of the bridge in Station Road is dry when there is still water in the river where it crosses the playing fields behind the Village College. We understand that this relates to a change in the underlying geology that occurs roughly along the line of Station Road, where it passes in front of Sheene Mill. The chalk that underlies the upper river, between Melbourn Bury and the bridge in front of Sheene Mill, is more ‘leaky’ than further downstream. This means that during a severe drought, when groundwater levels are low, water leaks out of the upper river back into the ground. Downstream of the bridge, the chalk is less transmissive, meaning that there is less opportunity for the flow to be lost. There is also some gain of flow here from several small springs that follow the line of the change in the underlying rock. Up until the beginning of December, the Environment Agency has, in times of drought, supported the flow of the Mel by pumping in water from a borehole at Newsells Park, near Royston into the lake at Melbourn Bury, thus supporting the whole length of the river. This support ceased in early December as the pumped water was only flowing for 10-15 metres before soaking back into the ground. Since then any flow from the upper river has ceased entirely. We understand that the Environment Agency is now questioning the sustainability of maintaining pumping in drought conditions. There are two main reasons for this. The first is that the water in the aquifer is being seriously depleted by pumping from the borehole at Newsells and the second is that the pumping seems to have little effect because the water is soaking back into the ground so quickly. As a Group, we were concerned to hear that both pumps were in fact broken and are awaiting repair (with one pump having been out of commission since last August). continued on page 15
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