Application of Clark’s Synthetic Unit Hydrograph Method with GIS for two Basins in Turkey

摘要

Determination of unit hydrographs for the basins is very important for the design of hydraulic structures. Unit hydrograph of a basin is derived from observed rainfall-runoff data of the storms, but if no observed data are available, it is obtained by using synthetic unit hydrograph methods. In this study, Clark’s synthetic unit hydrograph technique, is used together with Geographical Information Systems, where estimation of three parameters of the original methodology is required. Time of concentration is derived from SCS lag equation, reservoir storage coefficient from an observed storm hydrograph, and the time-area histogram from the digital elevation model of the basin. Then, by applying a unit excess rainfall over the basin, the translation hydrograph is derived from time-area graph. After performing a linear reservoir routing, the translation hydrograph is routed to the basin outlet and the Instantaneous Unit Hydrograph of the basin is obtained. Such a study is performed for two different size basins in Turkey and the results are compared with the observed unit hydrographs of the basins