Henley Whalers  Port  MollyMiniPic   Starboard   River Conditions at Henley


Can we row? If not, when? -
1a) River level
1b) How soon will Molly become accessible?
2a)  Flow rate ("Red/Yellow boards") -
2b) Flow rate at Maidenhead

Live reports - EA Flood warnings . AA Live Traffic map . Webcam at Hobbs.

Pictures of Winter floods 2013-2014
The hypothesis about rate of drop of flood-level. Other data.

Version 19/12/18

(1a) Is Molly accessible?

When the Marsh Lock downstream gauge reads 3.17m (maybe 3.2m?) or less, the concrete between Molly's two mooring posts is "dry", and "dry shoe" access is possible.
Check the ... DOTTED... line in the charts below. Press your Refresh" button to get the latest data.


Thanks to our Bob for his Continuous hourly plots
Alternative sources - Gov UK. website and "Shoothill"'s easy to read display.
"Normal High Water level" (as defined on E.A. website) is when the gauge reads 2.92m.

(1b) If Molly is not accessible - When will she be?

DIY Instant Rowing Date Prediction

In the charts above, is the level dropping convincingly?
If it is, get the Marsh Lock Downstream gauge reading.
Enter it here> metres (eg 3.69).
Expect to wait days before the concrete between Molly's mooring posts is "dry", but only if there is no further significant rain in the catchment area.

Rain Forecasts for the Catchment area are here (Oxfordshire) and here (Berkshire).- (The rain amounts tend to be overstated).

(2) What about River Flow Rate?- Can we row safely in fast water?

The EA chart says " " < Please tell me if you see grey bar here not text)
Yellow Board - YellowBoard "Stream Increasing/Decreasing" conditions present minimal difficulty.
Red Board - RedBoard "Strong Stream" conditions require greater respect but Molly can generally be rowed with suitable strong crew and skillful helm. Particular caution is essential upstream of obstructions and weirs.

2b) The Flow rate at Maidenhead is not very relevant to us because; (i) we are not at Maidenhead; (ii) with suitable crew we can row at quite high flow rates. It would be more useful to know the speed of the water at Henley, but we dont.

Flood warning GovUk (Henley).
Flood Warnings GovUk map
  Live traffic map
The AA Henley area.

at Hobbs of Henley

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Winter 2013 - 2014
Local average* rainfall for December is 106mm.
In December 2013 we had 129mm.
Local average* rainfall for January is 32mm.
In January 2014 we had 150mm.
Local average* rainfall for February is 36mm.
In February 2014 we had 133mm.
Good news - The forecast for March is much better! .

*(based on 3 yrs data)

Boxing day 2013
Whalers' Boxing Day Mince-pie row cancelled due to high river level.
So we waded to the bandstand on Mill Meadows.

We did not row from 11/12/13 till 12/3/14.
15 events were cancelled during 3 months of flood.

From our intrepid reporters

Thames side 10Feb pm
Thameside.10/2/14, 07:43.
(Thanks RM)
Gauge reading 4.22m

Hobbs Corner Feb10th
More from RM
"Hobbs corner", 10/2/14, pm.
Gauge reading 4.22m

Thameside 12th Feb
Another from RM
"Hobbs corner", 12/2/14, am.
Gauge reading 4.01m

Henley Thameside 13th Feb
RM again

"Hobbs corner", 13/2/14, am.
Gauge reading 3.93m

Shiplake lock & island, Thameside 8/2/14. See the river cascading across the island.
Shiplake lock flooded
Molly beached, Towpath 17/1/14.
Gauge reading 3.58m
Molly beached 17thJan

Boxing Day, December 26th 2013, 15:00. "Molly" accessible only to the intrepid (and waterfowl)

Other Boxing Day pictures click here

Boxing Day 2011
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Hypothesis - If the level is too high to row, when might we resume?

This Hypothesis Is based upon observations made during the winter floods of 2013 - 2014.

Graph 1Shows the water level (Marsh lock lower gauge) from 24th December 2013.

(The time scale is not quite linear, and there are gaps - One does need sleep! Normally 4 readings are recorded per day)

Marsh graph 1, Mar 3rd
Version 3/3/14

Graph 2Is the same as graph 1, with dotted lines added to highlight the "No-Rain Descent-Rate".
A rule-of-thumb "No-Rain Descent-Rate" appears to be 0.1m per day, but only if there is no further significant rain in the catchment area.Our Bob is working on a more accurate method..

Continue to Graph 3.

Marsh graph 2 March 3rd
Version 3/3/14

Graph 3

Shows Marsh Lock lower gauge reading from 16/2/14.
The "No-Rain Descent-Rate" (dashed and dotted lines) indicated the earliest date when access might have been possible if there had been no further significant rain in the catchment area.Even moderate rain can cause the level to deflect above the "No-Rain Descent-Rate".Further rain caused a final peak, 3.55m at noon on 5/3/14.
Whaling resumed on Wednesday 12/3/14. It is interesting to note that the final descent rate exceeded expectations, averaging 0.12m/day.


Marsh Lock gauge 03
Click for detail - Updated 9/3/14
Click HERE for "live" graph from our Bob

The minimum number of number of days to "normal level" = (Gauge reading - 2.92) / 0.1

The minimum number of number of days to "dry concrete" = (Gauge reading - 3.17) / 0.1
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Still reading?
A "rain amount" forecast is here - Experience has shown that the amounts are often overstated. Oxford was selected as being central to the catchment area.

Henley weather here (other forecasts here). Local rainfall records - Live weather data 5 miles west of Henley (usually upwind). Averages based on 3 years of data.

River levels Data - From St John's to Marsh - You can determine where the "crest of the wave" is.
StJ, Bus, Gra, Rad, Rus, Shi, Nor, Pin, Eyn, Kin, God, Osn, Iff, San, Abi, Cul, Cli, Day, Ben, Cle, Gor, Whi, Map, Cav, Bla (Ken), Son, Shi, Mar U, Mar D.
"Upper" gauges tend to show the rise and fall more clearly. (Using Firefox? - To save for future reference, when all are open, right click on a Tab, select "Bookmark all tabs")

Above Shiplake lock - A private data-set - River levels and more
Marsh & Shiplake locks - Gauge readings - Continuous hourly plots - (courtesy of our Bob) .

Can we row? If not, when? -
1a) River level
1b) How soon will Molly become accessible?
2)  Flow rate ("Red/Yellow boards")

Live reports - EA Flood warnings . AA Live Traffic map . Webcam at Hobbs.

If you'd like to suggest alternative material or presentation, contact webmaster .


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