Hydologic research about a drought in Simonoseki and Hirao district

From the datas of continuous drought days for 53 years in Simonoseki and Hirao, we found the logarithmic normal distribution curve is more fit than normal. √X and √^3X as distribution function. As a result, for example, we will have 29 continuous drought days once in 50 years and once in 500 years for summer in Simonoseki district. The calculated values of these continuous drought days is shown in Table 11. Moreover, in Table 12 and Fig.9, these values for 4 seasons (Spring, Summer, Fall, Winter) in both district is shown. These results Show considerable difference of continuous drought days in both districts and ones in Hirao districtis longer than Simonnoseki for every seasons. Reslt conduced here will be able to utilize in the decision of scale of dams.