TITLE:
Analysis of Rainfall Intensity-Duration-Frequency Relationship for Rwanda
AUTHORS:
Negash Wagesho, Marie Claire
KEYWORDS:
Intensity, Duration, Frequency, Maximum Rainfall, Regionalization, Rwanda
JOURNAL NAME:
Journal of Water Resource and Protection,
Vol.8 No.7,
June
16,
2016
ABSTRACT: Global atmospheric and oceanic perturbations and local weather
variability induced factors highly alter the rainfall pattern of a region. Such
factors result in extreme events of devastating nature to mankind. Rainfall
Intensity Duration Frequency (IDF) is one of the most commonly used tools in
water resources engineering particularly to identify design storm event of
various magnitude, duration and return period simultaneously. In light of this,
the present study is aimed at developing rainfall IDF relationship for entire
Rwanda based on selected twenty six (26) rainfall gauging stations. The gauging
stations have been selected based on reliable rainfall records representing the
different geographical locations varying from 14 to 83 years of record length.
Daily annual maximum rainfall data has been disaggregated into sub-daily values
such as 0.5 hr, 1 hr, 3 hr, 6 hr and 12 hr and fitted to the probability
distributions. Quantile estimation has been made for different return periods
and best fit distribution is identified based on least square standard error of
estimate. At-site and
regional IDF parameters were computed and subsequent curves were established
for different return period. The moment ratio diagram (MRD) and L-moment ratio
diagram (LMRD) methods have been used to fit frequency distributions and
identify homogeneous regions for observed 24-hr maximum annual rainfall. The
rainfall stations have been divided into five homogeneous rainfall regions for
all 26 stations. The results of present analysis can be used as useful
information for future water resources development planning purposes.