A decision support system, Daily Irrigation Network Operation Simulation model (DINOPS) was developed that can adequately describe the physical behavior of an irrigation system. The model is to depict the physical features of complex water allocation schemes of the irrigation system and to simulate the response of the system to different irrigation schemes. The model was validated on the Banweol irrigation district by comparing the simulated canal discharges and paddy water levels with the field data. The operation of the DINOPS model was demonstrated on the irrigation district where several irrigation management practices were evaluated with computing irrigation efficiencies and rainfall effectiveness respectively. The model sensitivity with respect to heights of bund and block diversion rates were analyzed and discussed.