THE RESERVOIR BEFORE THE FLOOD

Having now described the situation and construction of the reservoir, we will proceed to give a description of its condition a few days before its burst its embankment. 

DIGLEY VALLEY, SCENE OF THE BILBERRY FLOOD
(PHOTO FROM DAM TOP)

For two or three weeks before the 5^th of February much rain had fallen in the district, particularly on the Saturday morning before the accident. 

Monday and Tuesday were fine days, but on the Wednesday a heavy and continuous fall of rain took place during the whole day, which naturally filled the reservoir very rapidly. 

Added to this, strong winds prevailed all day and into the night. 

“The water in the reservoir,” says one eye-witness “was some little higher on Wednesday than I have seen it before.” 

As no gauging of the rainfall had been taken at Bilberry in the first week of February, we quote from a report made to the Manchester Corporation by Mr J.F. Bateman, C.E., who was then superintendent of the Woodhead Reservoirs, which are situated but a short distance on the other side of a chain of hills. 

Mr. Bateman said that on the first nine days in February, little less than 10 inches of rain had fallen, and that between 11 am on Wednesday the 4^th, and 11 am on Thursday the 5^th February, two inches and four tenths had fallen. 

So greatly did these rains swell the streams feeding the Woodhead Reservoirs, that, instead of an ordinary run of from fifteen to thirty cubic feet per second, he found the stream at Woodhead on the Wednesday pouring into those reservoirs an average of no less than 1,730 cubic feet per second; and after that time the stream rose at one period to from 3,600 to 4,000 cubic feet per second. 

This will give the reader some idea of the heavy rain fall which had taken place, and will account for the fatal accumulation of the waters in the Bilberry Reservoir.

We have already shown how ill prepared the outlets were to dispose of the surplus quantity, and how weak the embankment had become, from the errors of its original construction, and the casualties and wear and tear of about a dozen years from its completion.