Prepration and Assessment of Rainfall Depth-Area-Duration Curves in Esfahan Province

Flood risk estimation is one of the most important subjects for hydrologists and other scientists. The main objective of flood risk estimation is to study the past events in order to foresee the future flood risk. There are various methods for flood risk estimation. Rainfall- runoff and empirical equations are among the most used methods. In these methods, rainfall is the main parameter influencing flood mechanism. In this research, spatial distribution of rainfall pattern in Esfahan province is studied. Esfahan province with 10.5 million hectars of area has located in the central part of Iran with different topography, climate and ecological condition. Over 203 rain-guages located in the study area and its neibourhood were studied. The duration base of data record was 33 years. A total of 1654 storm events with less than 1 hour to 72 hours duration were considered, in which three index events, i.e. widespread and maximum events were used. The common methods of geostatistics, Krigging, Co-Krigging, IDW and TPSS were applied to interpolate the recorded points to non-observed ones. Among the studied interpolating methods, Krigging shows the best results, from which the Gussian and spherical models best fits to the observed points. In order to gain the best results, it is recommended to add the number of rainfall guage sites according to the World Meteorological Organization (WMO) standards. Also, we propose grouping the study area into homogeneous regions and studying DAD in each homogeneous region is advised.