Abstract:
The rainfall-Intensity-Duration-frequency (IDF) relationships is one of the most
commonly used tools in water resources engineering , either for planning ,
designing and operating of water resource projects. The IDF allows for the
estimation of the return period of an observed rainfall events for different time
durations conversely, it may be used to estimate rainfall amount corresponding to
a given return period for different aggregation times. The objective of the research
is therefore, to develop operational IDF relationships for the Burundi whole
country based on nineteen first class stations.
The annual maximum rainfall magnitudes of varying durations were collected from
rainfall charts and fitted to the probability distributions after which quantiles estimated for different return periods based on the best fitted distributions. Then,
the rainfall intensities are computed and the parameters of the general
mathematical form of IDF were generated for each station. Three different
methods expressing rainfall intensities were established for the study area: the
general mathematical form, curves relating Intensity-Duration-Frequency of rainfall
and IDF maps.
Burundi area has been regionalized and four different regions were established
based pooled quantiles of the 24-hour durations. The regional IDF parameters,
IDF curves and regression equations were developed for each region. This helps
to extract the intensity of rainfall of any durations and frequency at areas farthest
from the principal stations. The result of this research can be used to all water professionals and designers
on the activities of water resources and other related disciplines with in the region
by supplying important information's on rainfall Intensity, Duration and Frequency
relationships.
