Search of trade-off solutions at the water resources management in the interests of the Kuban river basin irrigation systems

The basin of the Lower Kuban is experiencing an acute shortage of water resources during the growing season. Every third year is low water year. Water Intake in the complex layout of rice irrigation systems requires reliable forecasting and skilful management. The Report presents the results of research and developed methods for finding the optimal operating modes for the water-resource system of the Lower Kuban based on hydrodynamic solutions and the trade-offs theory that ensure the reliable operation of rice irrigation systems, considering the conflicting requirements of water users. The methodology is based on multi-criteria analysis and hydrodynamic modelling with application of the ‘Operating Structures’ module, which, according to a given hierarchy of priorities, allows fulfilling the water users’ requirements to discharges and water levels during determined time period (water intakes and outlets points on the river network). The developed computational technology allows to reach reasonable compromise decision in the process of negotiations between water users and water basin authorities. the results of calculating the simulation model of two alternative scenarios for 2013. Blue scenario - the choice is made in favor of CHIS, black is made in favor of PAIS. On the lower graph, you can see that blue (CHIS) is above black, and on the top black (PAIS) is above blue (red - requirements). The given results show how well MIKE 11 abides by the hierarchy of water users' requirements priorities. To convert the results obtained during the simulation in MIKE 11 into Excel format, and to calculate the deficits for water users and the drawdown for the Krasnodar reservoir, a calculation scheme was developed. To drawdown the Krasnodar reservoir no more than 40% due to the small private fleet, to increase the water supply to PAIS-1, PAIS-2 by slight decrease in the total deficit and deficit for CHIS-1, CHIS-2 water users. The results of this research show the Sc69 scenario, in which the drawdown of the Krasnodar reservoir is 40%, the average deficit is 29%, and the total deficit is 20%. Deficits for other water users are respectively: 0%, 0%, 9%, 0%, 94%, 96%. This compromise scenario is agreed with the majority of interested water users and approved by the Decision Maker. Developed are the principles of water management in the cascade of the Lower Kuban reservoirs considering the forecast of the hydrological situation and the requirements of water users (rice irrigation systems). A hydrodynamic computer model of the Lower Kuban was created based on the use of the “Operating Structures” module, which allows to consider the hierarchy of priority of irrigation systems requirements during the vegetative period. Different scenarios for hydrodynamic calculations with a possible hierarchy of priorities were formed, scenario calculations were made, and a decision matrix was formed. A multi-criteria analysis of the decision matrix was made; a formulated and demonstrated was the computational technology that supports the negotiation process when choosing the “optimal” compromise solution for the operating modes of the Lower Kuban Water Management System in the dry year (2013).