Author(s): Ruochuan Gu
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Abstract: High water temperatures with long duration and large diurmal variations in summer months can be lethal to aquatic life (Sibley and Strickland, 1985). Maintaining water temperature standards during summers is important to the biological integrity of a warm plain river that serves as habitat for fishes and birds (Krapa, 1981).River temperature is a resulting variable, which follows a diurmal cycle and a seasonal cycle, due to the net of heat inputs and outputs under specific hydrologic and meteorological conditions. Of all the factors, however, discharge may practically be the only one that can be managed to alter the water temperature Quantitative relationships between water temperature and discharge can provide information regarding the river temperature problem in streamflow management and reservoir regulations for aquatic environment protection. Attempts were made to evaluate the effects of flow variables on river temperatures by Grant (1977), Hockey, et al. (1982), and Morse (1972) However, quantitative temperature-flow relationships under wide range of weather variables have not been successfully developed because the effect of discharge on river temperatures was not separated from that of weather. Moreover, sporadic and scarce field data were used in previous investigations, which were instantaneous river temperatures measured intermittently or randomly. To establish quantitative relationships, the impact of flow rate and depth needs to be isolated from that of climatic factors on river temperatures. This can be done by using a reference parameter characterizing meteorology. Water temperature variables must be precisely defined, such as daily maximum, daily mean, and diurmal variation. In addition, sufficient and continuous river temperature measurements are required for validation
Year: 1997