Rice, wheat or dust? Water resource carrying capacity estimation by degrowth transition scenario for Fars Province, Iran

Abstract

Agriculture remains the dominant consumer of freshwater globally, with projected increases in demand driven by irrigation expansion. In arid regions such as Iran, this intensifies competition among agriculture, industry, and ecosystems, exacerbating water stress—as evidenced by the desiccation of Tashk-Bakhtegan wetlands in Fars Province, a key source of dust storms affecting local communities. This study employs system dynamics modeling and the Water Resource Carrying Capacity (WRCC) framework to assess four degrowth scenarios focused on rice and wheat cultivation, evaluating their effects on water consumption and economic value-added. Results show that eliminating rice production and reducing wheat cultivation by 10 %, or converting 20 % of irrigated wheat to rainfed farming, yielded only marginal improvements in the Water Resource Carrying Capacity (WRCC) index. Reaching a sustainable WRCC demands at least a 25 % reduction in agricultural water withdrawals, with an associated 13 % decline in economic output. These findings highlight a nonlinear trade-off between environmental recovery and economic loss. By benchmarking extraction levels against ecological thresholds, this modeling framework promotes adaptive and equity-centered water governance in arid regions. It also provides strategic insight for long-term agricultural and industrial planning.