Winter-Regime Thermal Response of Heated Streams.

摘要

The one-dimensional convection-diffusion equation was solved to predict the winter-time temperature distributions and lengths of ice-free reaches in natural streams subjected to artificial thermal inputs. It was shown that the surface heat exchange between water and atmosphere could be expressed,for most practical purposes,as a linear function of the water temperature. The coefficients of the linearized heat loss model,applicable to laboratory conditions,have been developed from experiments conducted at subzero air temperatures. For determining the heat loss coefficients for field conditions,relations have been developed,describing the coefficients in terms of the meteorological parameters. Using the linearized heat loss term, a closed-form solution of the governing equation was developed to describe the temperature distributions under stable meteorological conditions and thermal discharge rates. For the general case with time-dependent climatic conditions and the thermal discharge rates, a numerical scheme was developed for the solution of the problem.