Knowledge of seabed/riverbed properties is required to predict mine burial, to study the effect of habitat on fisheries etc. Collection of samples of seabed/riverbed sediment and their characterizations are tedious and time consuming tasks even for a small area. The nature of seabed/riverbed will be affects on the characteristics of reflected echo. Mathematical modeling of the river bed system is designed. The modeling of the system is based on the acoustic behavior of river (water) and river bed (river bottom layer). Various types of losses in the acoustic signal at water layers are calculated using standard acoustic wave propagation equation. Using these loss parameters and other channel introduced noises, the system is mathematically modeled. Using the mathematical model, it is possible to predict the behavior of the system and reflected echoes. With the known transmitted signal parameters and created reflected echoes an algorithm is developed for extracting the required parameters like water depth and layer types. The algorithm includes acquisition of reflected echoes, removal of noise, envelope detection, and computation of echo amplitude and classification of layer type.