Operational performance improvements in irrigation canals to overcome groundwater overexploitation

Abstract

Groundwater overexploitation due to unsustainable agricultural development is a widespread problem in irrigation districts relying on conjunctive use of surface and groundwater resources. Nearly 90% of global groundwater supported irrigated areas have conjunctive use of both surface and groundwater. A major driver behind the use of groundwater in these regions, in addition to surface water scarcity, is the poor operational performance of the irrigation schemes. The lack of reliability of water deliveries at farm gates forces farmers to increasingly turn to groundwater. Therefore, they intensively extract water and continuously deteriorate groundwater aquifers. This case study investigates the potential impact of improved water distribution and delivery through implementing canal automation techniques. These techniques can enhance the reliability of irrigation deliveries to the endpoint, resulting in reduction of groundwater extraction and associated benefits in decreasing energy consumption and CO2 emissions. The current study focuses on six main irrigation districts located in the Zayandeh-Rud River Basin (ZRB) in central Iran, where a total area of 200,000 ha is irrigated using surface water in conjunction with groundwater. To improve the performance of the irrigation networks for each of these districts, three operational model alternatives, including fully automated systems, were considered. Each of these models was designed and run for each of the six districts separately. The results showed a reduction of operational water losses in the range of 15% –25% depending on the implemented operational model. These potential water savings are then available to be used in the agricultural sector and can result in a reduction in groundwater extraction of up to 300 Million Cubic Meters (MCM). The associated reduction in energy consumption and carbon emission was about 450 GWh and 57,500 t each year, respectively. The results of this study can be employed in designing a centralized configuration of automated systems that enable water managers to reduce pressure on groundwater resources.