WATER TEMPERATURE CHANGES AT HONMYO RIVER IN SUMMER AND ITS NUMERICAL SIMULATION

Temporal and spatial variation of water temperature has predominant effects on physical transport processes and biological and chemical transformations of substances in water area. Consequently, adequate understanding of water temperature changes is important facet of water quality management. In this study, field observations were carried out at the downstream reach of Honmyo River located at northern part of Isahaya Regulation pond. Furthermore numerical model for simulating water temperature changes was proposed and applied to this water area. Observed results show that thermal stratification is diurnally developed during dry weather condition. Redevelopment of the stratification after its dissipation due to the inflow of flood is subjected to temporal variation of wind speed. Although there is a room to tune the model parameters, proposed model simulates the observed results with acceptable error. Computed results show that thermal stratification is developed in all computed region. During the redevelopment of stratification, it takes a few days to raise water temperature in deeper layers.