Envelope curves for the specific discharge of extreme floods in Malaysia

The relationship between peak specific discharge and watershed area is examined for large, rare and extreme floods in Malaysia using a distributed hydrological model. Envelope curves for specific discharge for these events and the uncertainty is quantified. The relationships between rainfall duration and intensity as a function of watershed size were also examined. As a result, three main regions were defined to estimate the peak discharge as a function of watershed size for large, extreme and rare floods. The average magnitudes for the PMP and the world's extreme rainfall events were 5 and 12 times larger than the 100-year event, respectively. The envelope curves may assist engineers and other interested parties to estimate the peak discharge for watershed up to 100,000 km(2), especially for ungauged watersheds.