Abstract:This research applied a numerical marine model ECOM-si (estuarine coastal ocean model semi implicit), coupling a real time computational module of solar radiation intensity and sea surface heat flux, to evaluate effects of thermal water discharged from two coastal power plants (Guohua power plant and Wusha Mountain power plant) of the marine ranching zone in Xiangshan Bay. Affected by alternating tidal current, the effect on marine ranching zone of thermal water discharged from Guohua power plant was more significant than the water from Wusha Mountain power plant. The southwest side of ranching zone was easier to be influenced than the northeast side. Due to the fact that difference in air water temperature varies as season changes, the simulated data showed that each season had different temperature rise range and distribution characteristics around the ranching zone. During temperature rise period in spring, rise range was the largest, exceeding 1.0 ℃, its influential scope of temperature rise was the largest and its effect on ranching zone was also the most significant; nevertheless, during cooling period in autumn, temperature rise range was the smallest (within 0.3 ℃-0.5 ℃), and its influential scope of temperature rise was also the smallest. Winter and summer each was within low temperature period and within high temperature period, respectively. Differences in sea air temperature in both of the two seasons were small, temperature rise ranges were about 0.5 ℃-1.0 ℃, and their influential scopes were mediate.