| Summary: | Various models of the rainfall distribution to distribute a quantity of the
design rainfall during this a lot offered but the rainfall pattern analysis is done
separately between rainfall patterns and rainfall duration. Usually the rainfall
duration is determined without regard to the rainfall depth . While the rainfall
duration and the rainfall depth have a relationship. It is necessary to study the
influence in determining the rainfall pattern compared with no separation
between rainfall duration and rainfall patterns for design floods at each river
basin.
By using statistical analysis from rainfall events data, the frequency of
dominant rainfall events (rainfall depth and rainfall duration) that were analyzed
can be determined without separation. Analyses were performed with the help of
views WRPLOT software. The rainfall duration and the rainfall patterns that
represent das obtained based on the frequency of dominant rainfall events. The
design flood discharge is analyzed based on the rainfall pattern with the model of
rainfall flow transformation using unit hydrograph method.
Of the five river basin studied, the rainfall duration of each river basin is 5
hours for Bogowonto river basin, 4 hours for Progo river basin, 3 hours for Bedog
river basin, Code river basin and Gajahwong river basin. The resulting rainfall
pattern is the rainfall pattern based on the average dominant rainfall duration and
the rainfall pattern based on the overall rainfall duration. Generally, the
application of both the rainfall pattern of the design flood hidrograf gave no
significant difference so that the determination of rainfall pattern for river basin
can use the rainfall pattern based on the average dominant rainfall duration
because it's easier and faster.
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