抄録
The author estimated the potential evapo-transpiration from the observed air temperature, and calculated the water balance at Fukuoka. We can suppose that the amount of water surplus which was obtained above calculation, is the amount of effective precipitation. Monthly amount of effective precipitation is shown in Table 1. Table 2 shows the fluctuation of effective precipitation (1890-1955).
The amount of effective precipitation in the function of the amount of actual precipitation, evapo-transpiration and soil moisture storage. The relation between the amount of effective precipitation and actual precipitation is the most closely. The relation between them is shown in Table 3 and Fig. 1.
When the monthly total of precipitation and evapo-transpiration of two months are the same, as the daily amount of them are different, the monthly amount of effective precipitation should be differ. But we should not greatly error, if we assume the monthly calculated data as the actual amount of effective precipitation. The difference between the monthly data and the total of the daily data is shown in Table 4. Table 5 and Fig. 2 show the relation between monthly data and total of daily data.
