Document Type : علمی -پژوهشی
Authors
1
Ph.D Student in Climatology, Department of Geography, Islamic Azad University, Nour Branch
2
Associate Professor, Department of Geography, Islamic Azad University, Nour Branch
3
Assistant Professor, Department of Geography, Islamic Azad University, Nour Branch
4
Professor, Faculty of Earth Sciences, Shahid Beheshti University
Abstract
Quantitative forecasting and determining the processes involved in the production of surface runoffs and their transportation to the basin outlet is very crucial. The estimation of runoff production potential of a basin is highly important in soil and erosion conservation, as well as in managing the basins that produce runoffs and sediments. The Lavijrood watershed can produce seasonal floods; this is due to its topographical and physiological situation, climate system, non-compliance with technical construction standards, riverside violation, geology, and the other factors that affect the runoff production. In this research, we investigated the performance of the circular automata (CA) model as a suitable estimation method, and examined the possibility of integrating the method with the ArcGIS application to simulate the flood hazards and the hydrograph flow for the Lavijrood. The runoff level and the flood hazard were obtained through the SCS method. The flood simulation using the SCS method requires the data of land use, hydrologic groups of soils, Digital Elevation Map (DEM), rainfall, and the roughness coefficient of the basin. The raster format of all these layers was prepared with cell sizes of 30×30 m. Also, the flow depth and flow velocity were calculated based on the kinematic wave model and Manning equation; then travel time was obtained from the flow velocity. Based on these input data, the flood discharge time series graph was plotted for 35 maximum 24-hour rainfall events during the years 1994 to 2018. The correlation coefficients between the observational and simulated average discharge values in an hour and the maximum discharge of a 24-hour-rainfall in the Aghooz-Katty station were o.95 and 0.98, respectively. This means that, despite its simplicity, the CA approach provides realistic results for complicated natural events like runoffs. Furthermore, the error values of observational and average simulated discharges over an hour and the maximum discharge of a 24-hour-rainfall were 14 and 8.3 %, respectively, which shows a proper precision for the model.
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