Sensitivity analysis of a theoretical energy balance model for water temperatures is small streams

Abstract

Relative sensitivities were computed to determine the importance of the variables to the system. Sensitivity functions were used to predict the nature of the relationships between water temperature and the variables. Unlike earlier studies, this treats a stream subject to intense solar heating. The consequently elevated water temperatures, cause heat loss components to be significant. Evaporation and conduction are the most important. The analysis indicates that the wind spped, the thermal properties of the streambed, the season, its depth, and the amount of shading are the most important variables. The initial water temperature and the ambient water vapor pressure are less important. The air temperature, the albedo of the streambed, and the annual mean air temperature are of little importance. Neither the amount of turbulence in turbulently flowing water, nor the latitude of the stream has an effect. The model allows the trends of the system to be predicted on the basis of easily measurable variables. Hence, the difficulty of measuring the energy balance components may be avoided.