TITLE:
Regionalization of Rainfall Intensity-Duration-Frequency (IDF) Curves in Botswana
AUTHORS:
Berhanu F. Alemaw, Ron T. Chaoka
KEYWORDS:
IDF Curves, Design Storm, Probability Distributions, Clustering, Regionalization
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.8 No.12,
November
7,
2016
ABSTRACT: A
regional analysis of design storms, defined as the expected rainfall intensity
for given storm duration and return period, is conducted to determine storm Rainfall
Intensity-Duration-Frequency (IDF) relationships. The ultimate purpose was to
determine IDF curves for homogeneous regions identified in Botswana. Three
homogeneous regions were identified based on topographic and rainfall
characteristics which were constructed with the K-Means Clustering algorithm.
Using the mean annual rainfall and the 24 hr annual maximum rainfall as an
indicator of rainfall intensity for each homogeneous region, IDF curves and
maps of rainfall intensities of 1 to 24 hr and above durations were produced.
The Gamma and Lognormal probability distribution functions were able to provide
estimates of rainfall depths for low and medium return periods (up to 100
years) in any location in each homogeneous region of Botswana.