This paper introduces a kind of measurement method of the displacement for the water levels in river by the use of the laser distance measurement .The monitoring of water levels in river provides information about changes in water levels can support flood forecasting systems. Based on the principle of the laser reflection and fixed parameters of river bed, thus to obtain the actual data of the height of water levels. The empirical results for the weather and water properties it limited the wavelength of laser type used in this laser system by using three laser wavelengths 530,632.8 and 810nm. The study has been focused on the area located around the city of Hilla at shatt AL-Hilla in Iraq; according to the data collected from the Iraqi meteorological organization over successive twenty five years.