Modeling urban growth effects on carrying capacity in arid and semi-arid regions using system dynamics

Abstract

Urban carrying capacity (UCC) is essential to attaining sustainable development objectives. This study demonstrates the significance of strategies such as limiting built-up areas, preserving and expanding green and open spaces, and protecting water resources on health and urban carrying capacity in arid and semi-arid regions. This research is founded on the system dynamics model and aims to demonstrate, quantitatively and qualitatively, the interactions that affect urban carrying capacity between 2021 and 2040 in Tehran. The mean absolute percent error (MAPE), the coefficient of determination (R2), and the relative error (RE) all play a role in determining simulation accuracy. RE is less than 15 %, MAPE is less than 5 %, and R2 is more than 0.5, indicating that the system dynamics model adequately describes the actual behaviors. The results of the status quo scenario show that the current management policies will cause substantial damage to the environment, urban carrying capacity, and landscape subsystems and drive the system to an unsustainable level of water resources. In this scenario, between 2021 and 2040, water demand and built-up area increased by 26.26 % and 70.29 %, respectively, and in 2026, the Water Sustainability Index (WSI) will decline below 0.1, indicating that the water reserve cannot support the water demand after 2025. This study demonstrates that cities in arid and semi-arid regions cannot sustain continuous growth and physical development without considering the health of the primary carriers, such as spatial and water resources. In terms of health and urban carrying capacity, implementing a combination of policies aimed at enhancing urban green and open spaces and regulating water demand was the most effective. Also, considering that only ecological factors are considered in the present study, it is suggested that future research investigate economic and social aspects.