Scientific basis for efficiency of water supply assessment is the empirical dependence of crop capacity on water consumption under different climatic regions. Under the condition of water resource deficiency, low water and land efficiency, it is suggested to take into account the sufficiency of water supply not only during the vegetation period but also its distribution within this period (that is, the regime of crop irrigation), and also the mineralization of irrigating water, which is not done when conducting the present cadastre.
Efficiency of the water supply assessment for an irrigated area is calculated for every farm area. It consists of an average assessment over 3-5 years of actual water infiltration for crops conforming to the conditions of maximal crop growing. The irrigated area is considered supplied with water if:
where M^ is the water abstraction over a 5 year vegetation period (1,000 m3/ha); hc is the coefficient of efficiency of irrigation system; KB is the coefficient of acceptable decrease in average irrigation rate by which crop capacity decreases on and more than 10% of maximal crop capacity, which value is 0.83 (according to the general conclusion made by scientific production association CASRI); MpC.B. is the
The reasons of meliorative problems
Actions for improving meliorative condition
S.The optimization of meliorative regime.
9.Insufficient water supply of irrigation sources
The assessment of meliorative condition and meliorative actions h<[h]
3.The improvement of inventory supply and operational service mechanism
1 .Bad operating conditions and functionality
2.The choice of initial drain because of lack of drainage system by collectoers and excurrent trunl line.
4.Imperfection of meliorative regime
5.Low efficiency of farm-irrigation system
Ö.Low efficiency of interfarm-irrigation system
7.Imperfection of water abstraction from the sources of irrigation
8.The breach of crop designed structure lO.Miniralization increase of irrigation water
11. Insufficient washing regime in vegetation period
12. The lack of washing rate
13.Bad leveling of irrigated area
14.The setting of irrigation norms too high
15.The setting of washing norms too high
16. Extra feed source of ground water from overlying territory
1. Drainage refinement and repair
2.The construction of extra drainage
5.Reduction of crops to designed structure or reconsideration of irrigated area structure
6.The reconstruction of excurrent trunk line
7.The rise of water supply
9.The reduction of irrigated area
10.The improvement of washing technology
12. The reconstruction of farm-irrigation system by using antifiltration.
13.The reconstruction of interfarm-irrigation system by using infiltration
14. The reorganization of farm-irrigation system by using new techniques and technologies
15.The reconstruction of main water intake facility from irrigation source
16. The usage of drainage-sewage water for watering
17.The usage of pumped ground water for watering
Fig. 19.1 The scheme of analysis and the choice of actions conducting the meliorative cadastre value of calculated weight average irrigation rate with actual structure of crops taken into account (in favorable land conditions with water mineralization up to 1 g/l of unsalted land and ground water).
Depending on water mineralization and indices of the meliorative land condition, a correction is introduced into the equation as follows:
where the coefficient value y® psi is accepted according to the recommendations of Ikramov, R .
Under the condition of water resource deficiency and in the presence of large areas inclined to salinization, it is necessary to determine the efficiency of water supply over the period between vegetation (from November to April) using:
where B MB is the specific water abstraction for the period between vegetation, 3/ra; and BKflB is the supply for collector-drainage water irrigation, M3/ra.
Water feed is necessary during the period between vegetation and is calculated using:
where N .,, f. is the washing rate and area with ¿-level of salinization; j is the mechanical structure; S, SO is the initial and acceptable degree of soil salinization; mj3 is the rate of moisture filled watering for soil with i mechanical structure; j is the area with i mechanical structure, which requires moisture filled watering; KBMc is the coefficient of acceptable water feed reduction in the period between vegetation.
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