LENGKUNG HUJAN WILAYAH NUSA TENGGARA TIMUR

Sari

ABSTRACT

The calculation of flood discharge design requires intensity, duration, and  return periods can be obtained from Intensity-Duration-Frequency (IDF) curve. This study is the calculation of rainfall intensity in Nusa Tenggara Timur, then made in IDF curve.

This study analyzes the data are daily rainfall, rainfall data selection using the annual maximum series with 24-year data series (1988 till 2011), the frequency analysis to get rain when return periode 1, 2, 5, and 10 years, and the method of calculation of the intensity rain using Mononobe.

From the test results obtained match the best data distribution using the normal distribution. . Rainfall design, frequency analysis results, are used in the calculation of the intensity of rain is equal to R₂₄ = 47,694 mm for return periode 1 annual, R₂₄ = 68,764 mm for  return periode 2 annual, R₂₄ = 82,602 mm for  return periode 5 annual, and R₂₄ = 89,835 mm for return periode 10 annual. IDF curve Nusa Tenggara Timur for return periode 1 annual is y = 253,4x^0,667, for  return periode 2 annual is y = 365,36x^0,667, for  return periode 5 annual is y = 438,89x^0,067, and  for return periode 10 annual y = 477,32x^0,667. Where y is the intensity of rainfall in mm/hour and x is the duration of rainfall within minutes.

Keywords: rainfall intensity, Intensity-Duration-Frequency curve, rainfall design