In geographical areas subject to an arid climate, one of the most precious resources is water, which often get wasted due to inefficient irrigation systems. Automated irrigation systems which relies on closed loop control and feedback from sensors can help to closely match the water supply to the crop demand and avoid waste. In recent years, predictive control strategies were proposed for high tech watering systems which rely heavily on complex models incorporating variables such as crop water demand, soil evapotranspiration, weather conditions etc.. Through these models it is possible to anticipate the water demand of the crop, and give optimal irrigation scheduling with a significant reduction in water consumption. In this paper we developed a model of the soil moisture dynamics based on climatological data of the Kingdom of Bahrain. The model, which is based on the hydraulic balance approach, was validated by comparing its estimated output with real measurements. © 2018 IEEE.