1- University of Kashan
Abstract: (46 Views)
Introduction and Objectives: Watersheds function as the fundamental units of natural resource management. They play a pivotal role in providing essential ecosystem services, including hydrological flow regulation, biodiversity conservation, and the mitigation of soil erosion. Within the framework of sustainable development, these catchments serve as the primary spatial basis for integrated planning in water resources, environmental conservation, and the agricultural sector. However, anthropogenic pressures—such as intensive land-use changes and the overexploitation of surface and groundwater resources—combined with climatic stressors like recurrent droughts, have severely threatened the ecological integrity and health of many watersheds globally. In the Iranian context, the severity of environmental crises is underscored by several alarming indicators. These include a 37% reduction in reservoir inflows, the conversion of 66% of national wetlands into active dust storm sources (dust emission hubs), and critical land subsidence rates reaching up to 30 cm per year. Projections indicate that by 2041, between 50 and 70 million people in Iran will be exposed to extreme climatic events. Under such precarious conditions, the systematic and regular monitoring of watershed ecological health is a fundamental prerequisite for sustainable management. The concept of ecological health provides an integrated approach to simultaneously assess ecosystem structure and function. This enables the analysis of complex interactions among biological, physical, and human components. Among existing conceptual frameworks, the Pressure–State–Response (PSR) model has been widely applied due to its conceptual simplicity, clear causal relationships, and suitability for data-driven applications. By distinguishing between system pressures, the current ecosystem state, and management responses, the PSR framework provides a robust platform for analyzing the drivers of degradation and identifying potential restoration pathways. This study aimed to assess the ecological health of the Boushkan Watershed over a 15-year period (2011–2025 CE) using the PSR framework. The primary goals were to determine the spatiotemporal status of health, analyze the relative contributions of pressures, state, and responses, and propose practical, science-based recommendations for sustainable watershed management.
Materials and Methods: The Bushkan Watershed, encompassing an area of 37,838 hectares, is situated in southwestern Iran (Bushehr Province) and functions as a sub-basin of the Mand River Basin. The area exhibits a significant elevation gradient from 518 to 1,685 meters. This results in a hot desert climate in the lowlands and temperate conditions in the highlands. The mean annual precipitation is recorded at 286 mm, with a mean temperature of 21 °C. In this study, PSR indicators categorized into climatic, anthropogenic, and hydrological groups were assessed over a 15-year period (2011–2025 CE). These included Pressure Indicators (Quantifying environmental and human-induced stressors), State Indicators (Reflecting the current biophysical conditions of the ecosystem), Response Indicators (Focusing on management, conservation, and biological reclamation measures). Data were synthesized from multiple sources, including multi-temporal satellite imagery, hydrological time-series, base maps, technical reports, and socio-economic datasets. Spatial analysis and data integration were performed using Geographic Information System (GIS) tools. Indicators were standardized using linear relationship methods, accounting for their positive or negative impacts on watershed health. Weighting was conducted via the Analytic Hierarchy Process (AHP), based on the expert judgment of 25 local specialists and watershed management professionals.The Watershed Health Index (WHI) was calculated using a weighted average method. For spatial interpretation, the index was classified into five categories—unhealthy, relatively unhealthy, moderate, relatively healthy, and healthy—using the Natural Breaks (Jenks) method. Temporal changes over the 15-year period were evaluated by comparing maps from different periods and performing differential index analysis. Model validation involved field observations at 97 random points and non-parametric statistical tests, including the Kruskal–Wallis and Mann–Kendall tests. Model performance was evaluated through Overall Accuracy (OA) and the Kappa coefficient.
Results: The quantitative assessment of the PSR dimensions revealed that the weight of the Pressure dimension increased from 0.13 to 0.16 over the study period. Conversely, the State dimension decreased from 0.57 to 0.50, while the Response dimension increased from 0.30 to 0.34. The mean WHI of the Boushkan Watershed rose from 0.415 to 0.428, indicating a gradual positive trend in overall ecological health. Spatial classification results showed that the proportion of areas classified as "healthy" and "relatively healthy" increased from 42.1% to 51.4%. During the same period, the "moderate" category decreased from 41.2% to 32%. Areas classified as "unhealthy" or "relatively unhealthy" showed a marginal decrease from 16.7% to 16.6%. Statistical tests confirmed significant differences in the mean indices (Kruskal–Wallis H = 12.9, p = 0.002). Furthermore, trend analysis indicated a marginally positive trajectory (Mann–Kendall z = 0.82, p = 0.83). The model achieved an Overall Accuracy of 85% and a Kappa coefficient of 0.78. These metrics demonstrate high reliability and confirm the model's suitability for assessing watershed health in arid and semi-arid regions.
Conclusion: The results indicate that management interventions, specifically rangeland restoration and runoff management (including floodwater spreading and check dams), have contributed to a relative improvement in the ecological health of the Boushkan Watershed. However, persistent anthropogenic pressures particularly unsustainable agricultural practices alongside climatic stressors such as drought, continue to threaten the long-term sustainability of the basin.The PSR framework, characterized by high analytical precision and generalizability, proved to be an effective tool for monitoring watersheds in the arid regions of Iran. Despite limitations such as the scarcity of long-term socio-economic data, the results provide a reliable basis for sustainable planning. To enhance watershed resilience, the study recommends:1.Expansion of runoff control structures and flood spreading systems in critical southern and eastern areas, 2.Continuous spatiotemporal monitoring using GIS and Remote Sensing (RS), 3. Biological reclamation of rangelands using drought-resistant native plant species, 4.Mitigation of human pressures through stakeholder education and the implementation of strict restrictions on agriculture in steep-slope areas.
Materials and Methods: The Bushkan Watershed, encompassing an area of 37,838 hectares, is situated in southwestern Iran (Bushehr Province) and functions as a sub-basin of the Mand River Basin. The area exhibits a significant elevation gradient from 518 to 1,685 meters. This results in a hot desert climate in the lowlands and temperate conditions in the highlands. The mean annual precipitation is recorded at 286 mm, with a mean temperature of 21 °C. In this study, PSR indicators categorized into climatic, anthropogenic, and hydrological groups were assessed over a 15-year period (2011–2025 CE). These included Pressure Indicators (Quantifying environmental and human-induced stressors), State Indicators (Reflecting the current biophysical conditions of the ecosystem), Response Indicators (Focusing on management, conservation, and biological reclamation measures). Data were synthesized from multiple sources, including multi-temporal satellite imagery, hydrological time-series, base maps, technical reports, and socio-economic datasets. Spatial analysis and data integration were performed using Geographic Information System (GIS) tools. Indicators were standardized using linear relationship methods, accounting for their positive or negative impacts on watershed health. Weighting was conducted via the Analytic Hierarchy Process (AHP), based on the expert judgment of 25 local specialists and watershed management professionals.The Watershed Health Index (WHI) was calculated using a weighted average method. For spatial interpretation, the index was classified into five categories—unhealthy, relatively unhealthy, moderate, relatively healthy, and healthy—using the Natural Breaks (Jenks) method. Temporal changes over the 15-year period were evaluated by comparing maps from different periods and performing differential index analysis. Model validation involved field observations at 97 random points and non-parametric statistical tests, including the Kruskal–Wallis and Mann–Kendall tests. Model performance was evaluated through Overall Accuracy (OA) and the Kappa coefficient.
Results: The quantitative assessment of the PSR dimensions revealed that the weight of the Pressure dimension increased from 0.13 to 0.16 over the study period. Conversely, the State dimension decreased from 0.57 to 0.50, while the Response dimension increased from 0.30 to 0.34. The mean WHI of the Boushkan Watershed rose from 0.415 to 0.428, indicating a gradual positive trend in overall ecological health. Spatial classification results showed that the proportion of areas classified as "healthy" and "relatively healthy" increased from 42.1% to 51.4%. During the same period, the "moderate" category decreased from 41.2% to 32%. Areas classified as "unhealthy" or "relatively unhealthy" showed a marginal decrease from 16.7% to 16.6%. Statistical tests confirmed significant differences in the mean indices (Kruskal–Wallis H = 12.9, p = 0.002). Furthermore, trend analysis indicated a marginally positive trajectory (Mann–Kendall z = 0.82, p = 0.83). The model achieved an Overall Accuracy of 85% and a Kappa coefficient of 0.78. These metrics demonstrate high reliability and confirm the model's suitability for assessing watershed health in arid and semi-arid regions.
Conclusion: The results indicate that management interventions, specifically rangeland restoration and runoff management (including floodwater spreading and check dams), have contributed to a relative improvement in the ecological health of the Boushkan Watershed. However, persistent anthropogenic pressures particularly unsustainable agricultural practices alongside climatic stressors such as drought, continue to threaten the long-term sustainability of the basin.The PSR framework, characterized by high analytical precision and generalizability, proved to be an effective tool for monitoring watersheds in the arid regions of Iran. Despite limitations such as the scarcity of long-term socio-economic data, the results provide a reliable basis for sustainable planning. To enhance watershed resilience, the study recommends:1.Expansion of runoff control structures and flood spreading systems in critical southern and eastern areas, 2.Continuous spatiotemporal monitoring using GIS and Remote Sensing (RS), 3. Biological reclamation of rangelands using drought-resistant native plant species, 4.Mitigation of human pressures through stakeholder education and the implementation of strict restrictions on agriculture in steep-slope areas.
Keywords: PSR Framework, Analytic Hierarchy Process (AHP), Geographic Information System (GIS), Bushkan Watershed, Ecological Health, Sustainable Management
Type of Study: Research |
Subject:
ساير موضوعات وابسته به مديريت حوزه آبخيز
Received: 2025/11/25 | Accepted: 2026/02/25
Received: 2025/11/25 | Accepted: 2026/02/25
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