Asia Environment Simulator (AES) is a coupled system of computer simulation for meteorology, physical oceanography, land surface, vegetation, hydrology, coastal dynamics, and urban environment. The atmosphere, land surface, and hydrology models of AES have been applied to the analysis of the cyclone Gonu that had a landfall in Oman in June 2007. Gonu considered the strongest tropical cyclone ever recorded in the northern Indian Ocean, and the first fifth-category cyclone to enter the Arabian Sea. AES is applied to study the hydroclimatological features followed the landfall of the Cyclone Gonu in Oman. The significant discrepancy between the rainfall records at the ground rainfall gauges in Oman and the remote sensing estimates is clarified by using AES in simulating the cyclone Gonu hydroclimatological characteristics. Direct and indirect assessment methods show that the cumulative simulated rainfall depth is relevant to those estimated by satellites, whereas there is a considerable difference with the records at the ground rain gauges. By performing hydrological simulation of Wadi Hayafdh in Oman, it is found that the computed peak discharge and the runoff volume based on the ground rain gauges records are significantly higher than the corresponding observed peak discharge and runoff volume at the watershed outlet. Whereas, the computed peak discharge and the runoff volume based on computed rainfall depth are representing the observed values with high accuracy. Results from AES recommend instant assessment and evaluation of the ground rain gauges network such that it can be used safely in various future developing projects in the Omani area.