Application of Parameter Allocation Approach in Hydrological Modeling with MIKE SHE Distributed-Physical Model (Case Study: Ziarat Watershed, Golestan Province)

Parameter estimation is one of the main tasks in the hydrologic modeling. Parameter values can either be specified logically or blindly calibrated. In distributed physics-based models, it is arguably possible to specify parameters using catchment characteristics, hydrologic knowledge, the physics behind the parameters and how they function in the model. Such logic-based parameter specification is called as parameter allocation. This study tries to practice this modeling approach using the MIKE SHE model and simulate the overland flow in the Ziarat watershed. The model was executed using both approaches for a certain period from 01.23.2013 to 09.21.2014, and for the period from 04.15.2016 to 09.21.2017 as validation. The results of the simulation based on each of the approaches were evaluated by the Nash-Sutcliffe and Kling-Gupta efficiency criteria. Based on these efficiency criteria, the model in the parameter allocation approach has a good performance, and shows consistency in the validation period. Regarding the water balance, the results of the allocation approach are more resoanable and meaningful. Based on this, it can be concluded that spending more time to better understand the watershed charactristics and parameters of the model leads to more acceptable and consistent results that reduces the need for calibration significantly.