Determining the most appropriate distributions and intensity-duration-recurrence curves for the standart duration annual largest precipitations of Tokat, Samsun and Ordu provinces

The extreme precipitation values required in determining the flow rates required for the design of the surface drainage channels are obtained from the precipitation intensity-duration-recurrence curves developed as a result of the frequency analysis of the standard-duration annual maximum precipitations. In this thesis, the 50 years of Tokat, 59 years of Samsun, and 51 years of Ordu provinces standard duration (5-, 10-, 15-, and 30-minutes, 1-, 2-, 3-, 4-, 5-, 6 -, 8-, 12-, 18-, and 24-hour) largest annual precipitation data frequency distribution functions that best fit were determined using the FRANMOD model with the mean deviation (UQAD) from 1-1 line of the upper quartile data, upper tail Anderson -Darling (UTAn-Da), and right tail mean deviation (RTAD) of goodness of fit statistics. In general, the distribution that best matched has varied according to the provinces, standard durations, and statistics. It has been determined that the five-parameter Wakeby distribution comes to the fore in compliance with the annual maximum precipitation series for all three provinces. By comparing the measured and predicted precipitation values with the 1-1 straight scatter graph, the distribution that fits the best is decided. Using the best fit distribution in FRANMOD model, 2-, 5-, 10-, 25-, 50-, 100- and 200-year recurring rainfalls were estimated. The determined distributions and estimated precipitation amounts were compared with the data of the General Directorate of Meteorology of Ministry of Agriculture and Forestry of Turkish Republic. By using the obtained precipitation values, precipitation intensity-duration-recurrence curves for Tokat, Samsun, and Ordu provinces were drawn.