The relationship between rainfall intensity, duration, frequency helps
hydrologist to analyze the structural and hydraulic design of control
structures. This relationship was determined by statistical analysis of
sample records collected from different meteorological stations in
Colombo district. The hydrological design was considered at different
discharge rate for 2, 5, 10, 25, 50 years period of time. In order to
carry out this study, short durational rainfall data in wet zone were
collected from Metrological Department. Three frequency analysis methods
have been deployed to develop the curves. After analyzing the IDF
relationship with different approaches, the best approach has chosen
from the comparison. Selected best option could be used to identify IDF
relationships for the areas whereas there are no rainfall data. The
developed IDF curves are useful for safe design of efficient hydraulic
structures and for flood management in Wet Zone.