Daily graph and 24 hour forcast by the landowner Flood warning by Peter Colebrook of Marnhull (18 hours upstream of Bear Mead) <------1 day 9h-----> RAIN RIVER RISE Start End mms Start End

River height 204 at 1500 7 Feb 2010

River state: FALLING High

Floodplain state 20% flooded

River temp: 4°C River pH:    8.21 Last Flood: 9 Dec 2009

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Past Records: Graphs (77 months) Numbers (77 months) Location Display by year Averages Statistics

Floods since July 03: Analysis of Floods 2003 none | 2004 none | 2005 Dec 3 | 2006 Nov 26, Dec 31 | 2007 Mar 6 | 2008 Jan 16, Mar 17, Dec 15 | 2009 Feb 10, Nov 30, Dec 4, Dec 9 | 2010 - |

Report for 7 Feb: Rain: 0 mms River:204 Watertable:176

Forcast for 8 Feb: Rain: 24 hours River: 190 Watertable: 170

15 Nov - 13 Dec 2009 Heavy rain                       FLOOD-9       -10          -11 14 Dec - 11 Jan 2010 12 Jan - 9 Feb 2010

Future rain: Rainfall predicted over the next 24 hours by the BBC Weather Centre. The river responds in 24 hours to heavy rain. The river falls equally quickly. Also see: 5-day forcast Location of Bear Mead: Bear Mead is about 5 miles North West of Poole Harbour, Dorset, England

BBC Weather Forcast for this area Work out the probable amount of rain that will fall, and how it will affect the height of the river. 5 Day-FORCAST Hourly-RAIN Hourly-CLOUD Hourly-TEMPERATURE Hourly-WIND Jetstream

Rule of Thumb: The difference when stable between height of the Watertable (W) and River (R) decides the response of the River to Rainfall. If (W+60-R) is negative (dry ground), the River will hardly rise even after 30 mms of widespread Rain. If well positive (wet ground), the River may rise 250 cms in 24 hours for 30 mms of Rain. (W+60-R) usually becomes negative about early June and positive again about mid October, conveniently defining the dry season (summer) and wet season (winter). (W+60-R) has been observed with steady values in the range of +100 to -13. Present value of: (W+60-R)= +32 (wet)

A record of the Rainfall, Watertable and River Level of the River Stour at Bear Mead, about 2 miles West of Wimborne Minster, Dorset. Contact the author at for more information. see also: TIDAL TRENCH to control flooding. Unblocking, Tidying, Theory & early results, Results during flooding Mill Stream ditch

This website tries to give simple answers to questions about flooding on the Dorset Stour at Bear Mead. Where is Bear Mead? See Location What do the fields look like when flooded? See the pictures below How high does the watertable have to be before the fields flood? 220 cms How much rainfall is needed to make the river flood? About 10 mms rain for every 10 cms below watertable of 220 When is it likely to flood? When the watertable is about 200 cms (but depends how much rain arrives in next 36 hours)

How quickly will it flood? About 33 hours after heavy rain starts. How quickly will the flood disappear? About 48 hours after heavy rain stops. How deep underground is the watertable? (220-L) cms where L is the watertable level given above Are there past records for water levels? Yes, see Numbers. Are there graphs of how past levels have changed? Yes, see graphs. How has the river flow varied since 1968? See Flow

State of Flooding on the River Stour

Bear Mead sometimes floods after prolongued rain in the winter. The flood plain is 1200 yards wide at this point. There are spot OS heights of 19 meters, in Field 3 and on the access bridleway "D". The nearest official calibrated river height scale is at Corfe Mullen Mill, 1.5 miles up stream, easily read from the A31. There is a well in Field 5, enabling the water table to be monitored. An unofficial scale has been placed in the river at Field 1. Rainfall is monitored daily at the Author's home, 2 miles away. The official calibrated river height scale at Julian's Bridge, Wimborne showed 16.9 metres when the river at Bear Mead indicated 150 cms, so Bear mead should flood when the official scale reads 18.6 metres (assuming the weir near Eye Bridge has no effect). Similarly, the scale at White Mill showed 21.4 metres, and should read 23.10 when Bear Mead floods. These pictures, taken in 2000, show what happens when the floodplain floods. They were taken from Eye Bridge, because it is not possible to get onto Bear Mead itself without a landing craft! The floods usually arrive quickly but also depart quickly, leaving the ground very soggy indeed. The depth of the water-table is a good measure of the "sogginess".

6. The Stour and floodplain.

8. Approach bridleway to Bear Mead, 15 Nov 2002.

7. Car park at Eye Bridge

Bear Mead 14 Apr 2004

River Stour at normal height in Spring (145 cms)

26 Jun 2009. Thunderstorm over Poole, Dorset. 30mm rain in 9 hours

26 Jun 2009. Local rain runs into ditch then into river. Hump=250.

Flood delay in hours "It takes time for rain which falls over the catchment area to be converted into river flow and any floodwater which builds up takes time to flow downstream to the sea". SWGFL. Bear Mead is 33 hours downstream of rain Map of Catchment Area Historic Flood Rainfall Figures: Source: swgfl Year Month Total Interval Max/Day (mm) (Days) (mm) 1894 Dec 141.1 7 36.0 1916 Nov 134.7 8 29.0 1916 Dec 104.0 6 44.0 1933 Feb 89.9 3 56.0 1943 Feb 94.2 8 26.0 1954 Dec 84.9 5 27.0 1966 Nov 68.8 4 56.9 1979 May 105.6 11 35.0 1979 Dec 86.1 5 57.8 1990 Feb 78.0 6 25.0 1999 Dec 90.9 6 30.5 2000 Oct 80.2 6 35.0 Floods recorded on this website: 2005 Dec 30 2 22 2006 Nov 54 4 21 2006 Dec 54 3 27 2007 Mar 53 4 19 2008 Jan 42 3 26 2008 Mar 26 3 16 2008 Dec 20 1 20 2009 Feb 40 2 28 2009 Nov 37 2 23 2009 Dec 38 2 22

Nov-Dec 2009. The number of visitors to this website follows quite closely the height of the river, or perhaps my warning of a flood! If you are one of these users, please email and tell me your interest.

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