The Survey of Estimation Methods of Annual Discharge and Flood-Water of the Tighab (Catchment of Khash Township)

Tighab catchment has located between Khash and Iranshahr Townships. In this survey after collecting long time temperature, discharge and precipitation statistics (22 years) for catchment, we carried the research in two parts. The first section has been allocated for evaluating different methods for estimation of annual discharge of catchment and the second one for evaluating flood-water and selecting the best and the most appropriate methodology to estimate its value. Different statistical tests have been done on the data to ensure data homogeneity and distribution of selected stations, Using Justin, Indian Committee Agriculture (ICAR), Institute Irrigation Investigation up state of Indian and Lisi methods, the height of annual run-off has been calculated and the best method for estimating annual discharge was selected. Therefore, among used methods, Justin method gave better results because of considering more climatic and non-climatic parameters and regional coefficients for estimation of annual discharge. It is thereby suggested to be used in the Tighab catchment. At the next step, the regional flood-water has been studied and after estimating flood-water discharge in station, and investigating of different methods of flood estimation and selecting the most appropriate method at different return periods was also done. According to observed results, in order to obtain maximum floodwater momentary discharge, the SCS method shows more generality. In this study, since there is a serious limitation of ground water in Tighab region and so with the purpose of collecting and haltering surface and groundwaters, the attempt was focused on estimating both the value of annual discharge and the sub-basin flood-water of the study region.