Excessive flooding of the built-up territories in the areas of permafrost soils often occurs due to changes in natural factors (including climatic) or design deficiencies and can negatively affect frozen soils for a long time. Currently, there is no complete methodology for calculating this effect. The solution to this problem is closely related to clarifying the nature of the formation of temperature shift, which at the moment is not clear enough. The aim of the work is to create a methodology for predicting changes in soil temperature in the event of a shallow reservoir on its surface
In the first part of the article, the simplest theoretical model of the phenomenon of temperature shift is proposed, on the basis of which fairly convenient analytical expressions are obtained for the average annual temperature at the bottom of the active layer, depending on climatic factors and soil properties. The model most clearly demonstrates the nature of the occurrence of the phenomenon and can be used for simple assessments, as well as in the educational process. In particular, it is demonstrated that the magnitude of the shift is caused not only by the difference in the thermophysical characteristics of thawed and frozen soil, but also by the asymmetry of climatic parameters.
In the second part of the article, using the quasistationary methods, calculations of the predicted temperature of the soil when a reservoir of a given depth on its surface occurs. Unlike previously used methods, the predicted parameters of the soil are counted from its unperturbed state, which is determined by the authors previously proposed method, which allows us to evaluate the direction of the changes (towards cooling or warming). It is shown that the influence of a shallow (up to a meter deep) surface water body on the temperature of frozen soils substantially depends on the process of mixing water in the summer. For the first time, the direction of these processes has been established: with a high degree of mixing, the influence is always warming and grows with the depth of the reservoir; in the absence of mixing, the pond cools the base at shallow depths, and with an increase in depth above a certain value, an warming effect occurs, which, however, is much lower than in the presence of mixing. The practical applications of the results are considered.
