Designing an investment model and developing irrigation systems for sustainable management of water resources using a dynamic systems approach

Unsustainable groundwater management in Iran threatens the agriculture sector and food security because 62% of the country's lands are irrigated through groundwater, while the irrigation efficiency of this sector is low (35%). Therefore, it is necessary to manage groundwater level. This study was conducted aimed to achieve the sustainability of water resources in West Azerbaijan Province using system dynamics approach. Using statistical data of previous years (1991–2018), the model was developed by VENSIM software. After testing the model and ensuring its efficiency, scenarios of investment and development of irrigation systems to improve the annual irrigation efficiency by 0.5% were introduced to the model and implemented in order to investigate the effectiveness of other scenarios such as enhancing population (fertility stability with rate of 2.11 children, reduction in fertility with fertility rate of 1.95 children, reduction in fertility with fertility rate of 1.5 children and increase in fertility with fertility rate of 2.6 children) and climate (normal precipitation, −20% and + 20%), low-water use crop pattern, 20% reduction in area under cultivation, participation and educational scenarios in combination in the model. According to the study results, with the continuation of the current crop pattern under all population scenarios and precipitation, agricultural water demand from groundwater is constantly increasing and water supply is reducing. The scenario of development of irrigation systems in combination with other research scenarios, with a reduction by 48.23% in the demand for agricultural water from groundwater increased available groundwater under drought (−20% of precipitation) 3.05 times, in normal precipitation 1.59 times and by increasing precipitation (+ 20%) 1.07 times by 2051. Under these scenarios, with a 15% improvement in irrigation efficiency and an increase by 1.32 in agricultural water use efficiency, total water production will increase by 20.47% and total profit will increase by 26.87% by 2051. Therefore, the continuation of these policies can become a sustainable model in the agriculture sector and help the sustainability of water resources by preventing reducing groundwater levels.