Abstract:
This thesis studied and developed the mathematical model of water quality in 2dimension with average depth under unsteady state conditions. The objective is to predict thedistribution of water quality indices in Song Khla lake. The model development was based onthe momentum and continuity equations and the energy conservation equation for thehydrodynamic model and water quality model, respectively. The Alternating-Direction-Implicit(ADI) numerical method (Abbot Scheme) was used to solve the control equation of thehydrodynamic model. Meanwhile, the water quality model solved by the AD1 method using theQUICKEST Scheme and the 4th Order Rungkutta technique was found the biochemical equationof the 11 water quality indices : Salinity, Water temperature. Chlorophyll-A. OrganicPhosphorus (OP), Phosphate (PO4), Organic Nitrogen (ON), Ammonia (NH3-H), Nitrate (NO3-H), Dissolved Oxygen (DO), BOD, and other user defined toxic substances. Both models use theFortran Computer Language to construct the command procedures and to display thecomputational results in PC computer graphic.From the calibration, investigation and prediction with the recorded Song Khla data , itis found that the results of model are in good conditions, especially the calculation of thedispcrsion of the main water quality indices (DO and BOD). The other results of water qualityindices arc in acceptable criterion. The models of this study are able to use as the equipment forpredicting the impactions in water resources projects and managing the environment andecological systems for the shallow and wide water resources confidently.