University of Tehran Journal of Environmental Studies 1025-8620 51 1 2025 06 10 Quantitative Revelation of Regime Shifts in the Social-Ecological System of Zayandeh-Rud: Application of the Ball in the Basin Metaphor Quantitative Revelation of Regime Shifts in the Social-Ecological System of Zayandeh-Rud: Application of the Ball in the Basin Metaphor 75 95 102383 10.22059/jes.2025.388271.1008570 FA Majid Rahimi Social Business Institute, University of Tehran, Tehran, Iran. Mehdi Ghorbani Department of Reclamation of Arid and Mountainous Regions, Faculty of Natural Resources, University of Tehran, Karaj, Iran. Journal Article 2025 01 15 Objective: Interactions between human societies and natural ecosystems characterize social-ecological systems (SES), which, in turn, illustrate the dynamic interconnections among resources, land use, and water management. The goal of this research was to analyze and quantitatively disclose regime shifts in the social-ecological system of Zayandeh-Rud, which is one of Iran's important water sources, through the ball in the basin metaphor. Method: The research method involves the collection and analysis of time series data on surface water flow, water quality, groundwater levels, and agricultural land area. Using the sequential t-test method, regime shifts in the data were identified, and the obtained results and identification of critical thresholds assisted in this process. These critical threshold points were used to numerically calculate the depth of the basins in the ball in the basin metaphor. Then, through visualizing the regime shifts using this metaphor, different states of the studied systems and alternative stable states in these systems were analyzed. Results: The findings indicated that in the surface water subsystem regime, shifts were not identified in the Eskandari and Qaleh Shahrokh stations. In five other stations, at least one instance of regime shift was observed in the time series of surface water flow. Additionally, the analysis of Gavkhuni Wetland indicated the occurrence of regime shift in this wetland. In the surface water quality subsystem, no shifts were identified in the three upstream stations, while at least one regime shift was recognized in five other stations. Groundwater analysis showed the occurrence of regime shift with a decline in static levels in all 16 studied aquifers. Moreover, in the agricultural system, an increase in land areas was observed in the upstream region of the Zayandeh-Rud dam, accompanied by a decrease downstream and east of Isfahan. The results of applying the ball in the basin metaphor demonstrated that in the initial regime of all time series, resilience erosion led to shifts to other regimes. Additionally, the decline in resilience in some current regimes also indicated the system's movement toward another innovative regime. Conclusions: Regime shifts in the Zayandeh-Rud River Basin social-ecological systems arise from the complex interactions of human factors, together with natural factors, whose effects are majorly felt in the ecosystem and the local community; hence, a comprehensive analysis is vital. The excessive exploitation of natural resources resulting from human activity, particularly population growth and increased urbanization, has caused significant water quality degradation. It is also important to add that climate change and the increasing incidences of drought have further aggravated declining groundwater levels, which, in turn, have diminished the resilience of these ecosystems. Identification of threshold points and analysis of regime shifts enable managers to formulate effective management strategies and conserve the resilience of ecosystems. Objective: Interactions between human societies and natural ecosystems characterize social-ecological systems (SES), which, in turn, illustrate the dynamic interconnections among resources, land use, and water management. The goal of this research was to analyze and quantitatively disclose regime shifts in the social-ecological system of Zayandeh-Rud, which is one of Iran's important water sources, through the ball in the basin metaphor. Method: The research method involves the collection and analysis of time series data on surface water flow, water quality, groundwater levels, and agricultural land area. Using the sequential t-test method, regime shifts in the data were identified, and the obtained results and identification of critical thresholds assisted in this process. These critical threshold points were used to numerically calculate the depth of the basins in the ball in the basin metaphor. Then, through visualizing the regime shifts using this metaphor, different states of the studied systems and alternative stable states in these systems were analyzed. Results: The findings indicated that in the surface water subsystem regime, shifts were not identified in the Eskandari and Qaleh Shahrokh stations. In five other stations, at least one instance of regime shift was observed in the time series of surface water flow. Additionally, the analysis of Gavkhuni Wetland indicated the occurrence of regime shift in this wetland. In the surface water quality subsystem, no shifts were identified in the three upstream stations, while at least one regime shift was recognized in five other stations. Groundwater analysis showed the occurrence of regime shift with a decline in static levels in all 16 studied aquifers. Moreover, in the agricultural system, an increase in land areas was observed in the upstream region of the Zayandeh-Rud dam, accompanied by a decrease downstream and east of Isfahan. The results of applying the ball in the basin metaphor demonstrated that in the initial regime of all time series, resilience erosion led to shifts to other regimes. Additionally, the decline in resilience in some current regimes also indicated the system's movement toward another innovative regime. Conclusions: Regime shifts in the Zayandeh-Rud River Basin social-ecological systems arise from the complex interactions of human factors, together with natural factors, whose effects are majorly felt in the ecosystem and the local community; hence, a comprehensive analysis is vital. The excessive exploitation of natural resources resulting from human activity, particularly population growth and increased urbanization, has caused significant water quality degradation. It is also important to add that climate change and the increasing incidences of drought have further aggravated declining groundwater levels, which, in turn, have diminished the resilience of these ecosystems. Identification of threshold points and analysis of regime shifts enable managers to formulate effective management strategies and conserve the resilience of ecosystems.

https://jes.ut.ac.ir/article_102383_2e60c0f291ab36014bfa22efa3935c71.pdf