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| November 2012 and a high river level near the County Bridge, Brigg. |
Would you know where to find the current level of the River Ancholme in Brigg?
The Environment Agency posts this information daily. Here's a link..
Hopefully, you will never need to access this information after heavy rainfall, with flooding imminent. But it's good to know where to go if it happens.
And finally: Does anyone know how they measure the level of the river?
head were the motorway way bridge is there you find the level gage to warn boaters,the monitor device is at broughton bridge.
ReplyDeleteYes, and there is an Environment Agency monitoring station near the Leisure Centre bridge.
ReplyDeleteData is sent back electronically to EA's river level team.
Height of river levels is based upon the difference between a recognised datum point, which itself will be determined by the Newlyn tidal datum point, and the water level.
Another important aspect is flow......the Ancholme doesn't naturally discharge into the Humber.....it is related to the discharge rate at South Ferriby Sluice.
Without the sluice, the Ancholme would be tidal.
Unlike coastal areas, the Ancholme is fresh water and flooding results where run-off into the river from the Ancholme valley exceeds the river discharge rate.
However, the South Ferriby Sluice can only be used when Humber tidal levels are below the river level....and this also is affected by the monthly cycle of neap and spring tides.
On occasions when there are particularly high spring tides, the sluice maybe only open a few hours a day.
A particular dangerous time for flooding around Brigg is when there is a period of prolong heavy rain
combined with spring tides......resulting in a back-up of potential fresh-water flood water.
Just for information...during the retreat of the last Ice Age, 10k years ago....there was still a natural land-bridge from Britain to the Continent - Dogger Land and the Humber site was blocked by an ice plug.
ReplyDeleteDuring that time and until about 8k years ago, the river in the Ancholme valley flowed from N to S ...from the Humber towards the Wash.
This glacial run-off gave rise to the various geological deposits about Brigg......gravel pits and clay pits, for example, which promoted the numerous brick kilns in latter years.
Once the Humber ice plug (also a lake) was released, the Ancholme valley was regularly flooded my marine deposits.....hence the pockets of marine sand and silts about Brigg.
In about 500 BC there was an extreme storm that deposited a marine sand bar across the Ancholme north of Brigg....in turn the area about Brigg became a lake for a couple of hundred of years.
It was this increased flooding that encouraged the Bronze Age settlement in Brigg to leave....it had already covered the Bronze Age boats and the plank way that crossed (or possibly partially crossed) the valley...