The thermal resources of the evaporation
process for any calculation period are defined as:
LE mi ¼ R
þ
i þ P
þ
i Æ DB i À DE 0i ;
ð5Þ
where E mi —the equivalent of the thermal
resources by the maximum possible evaporation,
m; L—the latent warmth of evaporation, j/m
3 ;
R
þ
i —the positive component of the radiation
balance, j/m
2 ; P
þ
i —the positive component of
turbulent warmth transfer, j/m
2 ; DB i —changes of
the warmth stocks of the active layer of soil,
j/m
2 ; DE 0i —warmth consumption for melting of
snow, ice, the warming of the soil, j/m
2 .
Due to the limitations of the initial data for the
radiation regime and turbulent warmth transfer, it
is difficult to use the Eq. (5) in practical calculations. Studies have shown that the optimal
distance between actinometric stations should be
no more than 100 km. In the existing network of
actinometric stations, this condition is not satisfied. Therefore, one needs to find the connection
elements of the radiation balance with the climatic parameters.
Currently, there are a lot of dependencies to
determine the annual standards of E 0 in the case of
Belarus by the sum of temperatures above 10 °C.
We have found the approximate solution of
Fig. 3.1 The Neman River basin
3 Forecast Changes in Runoff for the Neman River Basin
15