Rainfall Intensity–Duration–Frequency Curves Using Cluster and Regional Frequency Analyses

• Published in: Journal of hydrologic engineering Vol. 29; no. 5
• Main Authors: Iresh, Attidiyage Don Shashika, Obeysekera, Jayantha, Athapattu, Bandunee Champika Liyanage, Fernando, W. C. D. K.
• Format: Journal Article
• Language: English
• Published: New York American Society of Civil Engineers 01-10-2024
• Subjects: Arid zones; Case Studies; Case Study; Climate; Climate variability; Climatic conditions; Cluster analysis; Duration; Frequency analysis; Hourly rainfall; Maximum rainfall; Precipitation; Project management; Rainfall; Rainfall intensity; Rainfall patterns; Regional analysis; Regional development; Regions; Resource management; Water resources; Water resources management; Sri Lanka
• ISSN: 1084-0699; 1943-5584
• DOI: 10.1061/JHYEFF.HEENG-6167

AbstractThis study exemplifies the need for updated intensity–duration–frequency curves in Sri Lanka to better reflect current climate conditions. The coupled use of cluster analysis and regional frequency analysis was effective for identifying 11 meteorologically homogeneous regions, leading to the development of new regional intensity–duration–frequency curves. Data screening techniques identified reliable daily and hourly maximum rainfall records, enabling the classification of Sri Lanka into these regions. The regions capture the varying rainfall patterns across the country, from wet zones to arid zones. The curves were constructed for return periods ranging from 2 to 200 years for the selected meteorologically homogeneous regions covering durations up to 72 h. The curves provide updated empirical formulas for estimating rainfall intensity for different durations and return periods, crucial for hydrological designs. Comparison with previous intensity–duration–frequency curves highlights significant differences, especially in short-term intensities, likely due to recent climate variability. The newly developed regional intensity–duration–frequency curves are recommended for water resource management projects, although the study suggests further analysis over longer periods with additional data for enhanced accuracy. Overall, the study fills a long-standing need for updated intensity–duration–frequency relationships in Sri Lanka.