Developing an Expert System for Predicting Pollutant Dispersion in Natural Streams

In recent years, preservation and purgation of rivers is considered by national and international organizations that have responsible of quality control and preservation of water resources. Because of providing public health, it is most important and vital in regions that cities that rivers feed drink waters and large industrial factories located near these rivers (Li et al., 1998; Pourabadei & Kashefipur, 2007; Tayfour & Singh, 2005). So it is clear that estimation and simulation of flow, contaminant and sediment transport in river and water systems have more significance in water resources management. Using precious estimations reduces the risk of contaminant and pollutants on environment in now and future and increases the impact and effectiveness of environmental engineering projects on water recourses quality (Li et al., 1998 ;). The increasing process of pollution on surface waters necessities the requirement of using mixing and attenuating processes in natural rivers. One of the most important, proper and prosperous methods of river environmental management is using and improving of river self-cleaning ability. Now sinking of several types of agricultural and industrial Remainders into natural rivers to oxidize and elimination of organic materials is a usual management operation in environmental engineering. To control the quality of surface water resources, the sinking of pollutants into natural rivers and open flows should be done under a precious and logical method. This action requires the detailed knowledge and information on pollutant transfer in rivers and the ability of transporting, mixing and self-cleaning of pollutants by river flow (Pourabadei & Kashefipur, 2007 ;). Contaminants and effluents undergo stages of mixing with flow and dispersed longitudinally, transversely and vertically by advection and dispersion transport processes. Contaminants and effluents due to advective and dispersive processes of river flows, propagates in longitudinal, transversal and vertical directions (Tayfour & Singh, 2005). Ability and power of river and other open channel flows in dispersing additive materials in longitudinal, transverse and vertical directions addressed and described by dispersion coefficients. Three dispersion coefficients KX, KY and KZ show the dispersion coefficients in longitudinal, transverse and vertical directions respectively (Tayfour & Singh, 2005). Far from the point of injection of pollutants to river where the mixing process is completed over all the cross section, only longitudinal dispersion is dominant and all of the dispersion phenomena are described by KX