XVIII. 



THE FLOODS OF NOVEMBER, 1894, IN HERTFORDSniRE. 



By John Hopkinson, F.L.S., F.G.S., F.R.Met.Soc. 



Read at Watford, 26th March, 1895. 



The immediate cause of the floods which occurred in the South 

 of England and South Wales in the middle of November, was 

 a heavy fall of rain which commenced on Monday night the 1 1th, 

 or Tuesday morning the 12th, and lasted until about mid-day 

 or rather later on Wednesday the 14th, with one intermission 

 of considerable duration in most districts. In Hertfordshire there 

 were two distinct falls : the first commenced about the middle 

 of the night of the llth-l'ith and ceased about noon; the second 

 commenced about the same time in the night of the 13th-I4th 

 and ceased early in the afternoon of the 14th — ceased, that is, as 

 a heavy fall, for a little rain fell later in the day. On the 

 morning of the 13th the sky at St. Albans was perfectly cloudless 

 and the weather was fine throughout the day. Each of these falls 

 lasted about twelve hours and averaged about an inch and a half. 

 But the severity of the floods was due in great measure to another 

 cause, the saturated state of the ground upon which this heavy 

 rain fell. From the 1st to the 10th of November there was but 

 little more than the average rainfall, but during the previous 

 nine days, October 23rd to 31st, nearly two and a half inches 

 of rain fell in our county. And it was much the same throughout 

 the southern half of England and the greater part of Wales. 



October and November are usually rather wet months, our 

 rainfall in October being about three-quarters of an inch above 

 the average for all the months in the year, and in November being 

 about one-quarter of an inch above this average, so that we have to 

 compare an exceptionally wet period with a season which is 

 usually a wet one, otherwise the following comparisons would 

 have been much more striking than they are. 



During the nine days from October 23rd to 31st the mean 

 rainfall in Hertfordshire was 2'38 inches, or an average of 

 0*265 inch per day, being nearly three times the usual fall for 

 the time of the year; during the ten days from November 1st 

 to 10th the fall was 1-02 inch, or an average of 0-102 inch per 

 day, being only 20 per cent, above the usual fall for this period ; 

 and during the four days from November 11th to 14th the fall 

 was 2-97 inches, or 0'742 inch per day, being veiy nearly nine 

 times the usual daily fall for November. Taking the whole 

 period of 23 days from October 23rd to November 14th it will 

 be found that the fall was more than three times the usual 

 quantity, for this gives an avertige of 0-277 inch per day against 

 the usual average for October and November together of 0-088 inch 

 per day. These comparisons are on the average of 50 years rainfall 

 in Hertfordshire ending 31st March, 1892. 



