Conceptual principles of water resources management in irrigated agriculture

Climate change manifested in Ukraine by rapid (over 0.6^oC in 10 years) increase in average annual air temperature causes a progressive deterioration of natural water supply significantly increasing the need for irrigation to ensure sustainable agriculture.

"Irrigation and Drainage Strategy in Ukraine until 2030" provides for an  increase of irrigated lands area up to 1.5-1.7 million hectares and the corresponding significant increase in water consumption from the current 1.5-1.8 billion m³ to 5-6 billion m³. Given that climate change has a negative impact not only on the state of natural water supply, but also on the state of available water resources, their rational use in irrigation is an important component of sustainable water management.

Effective tools for its implementation in irrigation are decision support systems. Their usage provides a capability to achieve maximum irrigation efficiency when complying with the following provisions:

- Irrigation should maintain root layer moisture content in a narrow range of high values (from 0.8-0.85 of field capacity to field capacity);

- Tensiometric pressure should be used as a criterion of moisture content and moisture availability for plants;

- Water retention curves should be used to determine field capacity, pre-irrigation thresholds, and optimal ranges of moisture available to plants;

- Moisture transfer models for saturated-unsaturated soils stated in terms of pressure can accurately predict irrigation schedules and rates;

- The combined use of several methods for evapotranspiration assessment improves the accuracy of calculations;

- Remote sensing data can be used to tranfer irrigation schedules and rates predictions to the areas not covered by instrumental monitoring tools.

The application of these principles provides for

- an increase in crop yields accompanied by irrigation water volumes reduction;

- irrigation with environmentally friendly rates minimizing water losses for infiltration, and the development of flooding and secondary salinization processes.

The introduction of these principles in practice will increase the sustainability of water management in agriculture in the conditions of climate change, and the use of decision support systems at full scale will ensure the maximal materialization of the potential of crops’ varieties and hybrids.