Pengaruh Jumlah Data Hujan Maksimum Terhadap Data Hujan Rancangan

The influence of the maximum amount of rainfall data on the design rain, on the Kali Birin Sub Watershed Dengkeng tributaries will greatly affect the amount of rain depth value in a particular return period. The availability of data on the DPU for water resource management in Klaten, Central Java is quite complete, so a design rainfall analysis can be done. Calculation of rain frequency analysis can be used with the help of the Aprob_4.1 computer program, this computer program is only used for the calculation of frequency analysis which will produce the determination of the distribution used and the determination of 2, 5, 10, 20, 50, 100, 200, 500 and 500 1000 years. Taking the amount of data n = 16 to n = 30 data. The results of the calculation of the amount of rain data that is believed to be a reference to analyze deviations from the return value of rain from 2.5.10 to 1000 is 28 data, the amount of rain data that is farther from 28 data, shows the greater deviation. The deviations are as follows: for the smallest amount of rain data (n = 16) of 7.692% to -3.750% (when 2 years to 1000 years), (n = 18) an error of 5.769% to -3750% occurred, (n = 20) there was an error of 3,846% to 2,500%, (n = 22) there was an error of 1,923% to 2,500%, (n = 24) there was an error of 0% up to 1,2500%, (n = 26) an error of 1.25% to -1.96% and the last (n = 28) an error of 0% occurred. The minimum amount of rainfall data that is still feasible to use for frequency analysis is 20 data, with deviations