Assessment of the Variations of Local Parameters of Wetspass Model: Case Study Nile Delta Aquifer

Assessment the variation of WetSpass model parameters in the Nile Delta aquifer, Egypt is very significance before applying it to estimate the variations of groundwater recharge from rainfall. The input WetSpass model parameters are investigated based on the soil type, crop classification, and the previous studies. The input model paramters are crop height (hc), root depth (rd), Interception percentage (I), leaf area index (LAI), bulk resistance (rs), roughness length (z) and zero plane displacement (d). The investigation results of this paper indicate that the local model parameters have a great variation. The WetSpass model was calibrated for crop height hc in a range between 0.4 m to 1.0m. The RMSE between the simulated WetSpass value and the calculated one increased with the increase of hc. The minimum RMSE equals 8.13 mm/winter season at hc equals 0.4m. An extensive sensitivity analysis is required for all WetSpass parameters for the accurate determination of the model parameters.