A Sensitivity Study of some Hydrologic Empirical Methods for Estimating Flood Peak as Related to Drainage Area in Watersheds in Iran

Design flood is an indispensable criterion in many water projects. Unfortunately , many of developing
countries including Iran are faced with lack of sufficient recorded hydrologic data. Thus, in order to cope
with data scarcity and study ungauged catchments, application of developed empirical models based on other
gauged catchments is a common strategy used by hydrologists . The present research work is an effort to
evaluate a number of ten general empirical models for flood estimation with different return periods. The
models include: Dicken, Creager, Gray, Bremner, Waitt, Inglis, Cramer, Murphy, Ocornell and Cooley. The
models have been tested in the major Iranian watersheds namely the Caspian Sea basin, the Persian Gulf and
Oman Sea watersheds, the Uromia Lake watershed and the Central Deserts catchments . The results highlight
that the Bremner Model is best for shorter return periods in Caspian Sea watershed whereas Murphy Model
can act better as a general model over there. In the Persian Gulf and Oman Sea watersheds, the Dicken Model
with an exponential form shows better results. However for short return periods the Gray model is better. In
Uromia Lake watershed-all models except Gray are applicable. In the watersheds of the Central Deserts, for
shorter return periods the Murphy Model gives better results whereas for longer return periods Cramer is the
most suitable. The present study shows that the most suitable range for study area varies from 1400 to 2400K.m2