evaporation under optimal humidity conditions, mm; Р, m - rainfall and irrigation rate,
mm; A - reduction coefficient, which shows decrease of total evaporation at decrease
of soil moisture below critical values W<W
кр
; К - reduction coefficient, which shows
reduction of total evaporation for the values of the calculated layer of soil h<1 m and
the values of the root layer h
к
>h.
Figure 2. Functions of the additional net profit from irrigation, depending on the
irrigation rate and the value of the payment for water:
1 – the optimal value of the irrigation rate, which corresponds to the maximum
point of the criterion value at water tariff
= 0,2 uan;
2 – suboptimal values of irrigation norms (interval) corresponding to the value
of the criterion for water tariff
= 0,1 uan;
3 – suboptimal values of irrigation norms (interval) corresponding to the value
of the criterion for water tariff
= 0 uan.
To improve the two-layer model, more adequate reflection of the processes of
moisture transfer, for the operational planning of irrigation a multilayered model is
proposed (Fig. 3). The research has convincingly proved that on the basis of the concept
of the thermodynamic potential of water in the soil it is possible to obtain a satisfactory
description of all the most important processes of redistribution and flow of soil
moisture (Fig. 3). The mathematical description of the motion of moisture in saturated
3
2
1
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