Rainfall Intensity-Duration-Fraquency (IDF) Curves For North-East Region of Yangon-Myanmar

Rapid urban expansion in the Yangon Region - Myanmar, combined with rising rainfall intensity and insufficient drainage capacity, has increased the risk of urban flooding in recent years. Accurate Intensity–Duration–Frequency (IDF) curves are essential in planning and design sustainable drainage infrastructures, flood risk assessment. However, the availability of long-term, high-quality rainfall records are very limited. This study aim to develops IDF curves for ungauged townships in the North-East Region of Greater Yangon using nearby ground-based Hmawbi meteorological station data (2010 – 2019) combined with long-term satellite-based Integrated Multi-satellite Retrievals for GPM (IMERG) data (1998 – 2024). After analyze multiple probability distribution functions, Log Pearson Type III was identified as the best fit probability. Mononobe method is then used to disaggregate daily rainfall intensities into shorter durations of 10 – 120 minutes and IDF relationships were then developed using the Sherman equation for different return periods of 2, 5, 10, 25, 50, and 100 years. Comparison between observed and IMERG-based IDF curves for the Hmawbi reference township (2010–2019) showed excellent agreement with R² values close to 1. The high consistency indicates that IMERG data can reliably be used without bias correction. IDF results from the study townships indicated that those adjacent to rivers and in low-lying zones exhibit higher rainfall intensities than those at relatively higher elevations. This study approach can be replicable to any other ungauged, flood-vulnerable major cities, which will contribute significantly to flood resilience and infrastructure planning across the country.