Rainfall-runoff modeling based on system dynamics approach(Case study: Mashhad Kardeh dam basin)

Rainfall-runoff modeling is on of runoff estimation techniques and an appropriate tool for studying hydrological processes, water resources evaluation and watershed management. But the complexity and the non-linear nature of rainfall-runoff process and not being known factors affecting it and generally on discharge at watershed outlet, modeling has become more difficult. Therefore, using the methods that have additionally dynamic, development capability, conceptual structure and user friendly is essential. Therefore, in this study for rainfall-runoff modeling were used system dynamics methods in the Kardeh dam basin of Mashhad. The proposed model includes 6 reservoir including snow storage, canopy storage, impervious storage, surface soil storage, subsurface storage and groundwater storage. The input data required includes average daily precipitation and temperature. To calibrate the model daily discharge data from basin outlet in the period from 1998 to 2008 and for evaluation the discharge from 2009 to 2012 were used. The results of sensitivity analysis showed temperature parameters are more sensitive and have considerable impact on discharge and peak flow. Also the results indicate that the simulated stream flow pattern is quite similar to that observed and Nash-Sutcliffe coefficient obtained in the evaluation period between 0.57-0.67 which represents that the system dynamics methods is high ability to rainfall-runoff modeling.