By A Correspondent| A research paper suggests that Zimbabwe was warned of impending cyclone floods as far back as 1934.

The Rhodesian paper, follows indications by a 96 year old man interviewed by ZimEye.com who reveals that cyclone Idai is not the first to hit Zimbabwe. He during the week told ZimEye there was another cyclone which hit Chimanimani back in 1932.

The elder’s video footage will be streamed on Sunday morning.

In the below research paper extract dated 1934, Rhodesian engineers are seen planning for another flood that will happen in less than 100 years. The extract reads as follows:

For the range of conditions under consideration the following formula gives values of C closely in accordance with the values derived from Mr. Creager’s equation, and it has been used to calculate the values of C presented in the last column of Table IV :- C = 6,00011 + 0.07( )] X run-off X 1,000 – A (gathering-speed)o’6 (length : max~-breadth)~’~’

This formula, although somewhat cumbersome, has the advantage of enabling the value of C for a given catchment to be estimated in a rational way, and not merely guessed at. The catchment area, A, and the ratio of length to mean breadth can both be taken direct from the map of the catchment-area, and there remain only two uncertain factors, the run-off and the gathering-speed, a fair estimation of which can be formed from a knowledge of the physical characteristics of the catchment. It will usually be more accurate to estimate these factors separately than to make allowance for the conflicting effect of a number of factors whose relationship is Unknown.

PROBABLE FREQUENCY OF FLOODS. Mr. Creager gives the formula :- where Q denotes the peak discharge of maximum flood probable in T years, C ,, co-efficient discussed above, e ,, base of the natural system of logarithms. A ,, catchment-area in square miles. The terms in the bracket represent the fraction of the probable maximum flood which may be expected to occur once in T years.

If 100 years is taken as a reasonable figure for works which are not of great importance, and whose failure would not entail loss of life, then it is found that the fraction varies between 0.586 and 0.629 for the catchments described in this Paper. It would therefore appear that floods equal to 67 per cent. of the probable maximum may be expected less than once in 100 years, and that to design for floods of 75 per cent;. of the maximum calculated discharges would allow a substantial margin of safety.