Introduction

The desiccation of Lake Urmia is regarded as one of the most prominent examples of ecosystem collapse in the semi-arid regions of the world. As a saline aquatic ecosystem, the lake has played a vital role in regulating regional moisture regimes, moderating thermal fluctuations, maintaining biodiversity, and supporting ecosystem services. The substantial decline in water level over the past two decades has not only altered the structure of the ecosystem but has also increased the risk of salt-dust emission hotspots, degraded the quality of surrounding soils, and undermined the lake’s unique ecological values. Despite the extensive body of research conducted on the subject, most studies have focused on one or a limited number of individual drivers and have failed to provide an integrated framework for prioritizing the contributing factors and elucidating their causal chain through to policy responses. Accordingly, this study employed an integrated AHP–DPSIR approach to identify, prioritize, and structurally analyze the factors contributing to the decline in Lake Urmia’s water level.



Materials and Methods

In terms of its objective, the study is applied in nature, while methodologically, it adopts a descriptive–analytical design based on a mixed-methods approach. The research was conducted in three main stages. First, the factors contributing to the decline in Lake Urmia’s water level were identified through a systematic review of the scientific literature. In the second stage, the relative importance of the identified factors was determined using the Analytic Hierarchy Process (AHP). For this purpose, a panel of 30 leading experts in natural resources, environmental sciences, water engineering, and related fields, including researchers and university faculty members, was established to constitute the Expert Panel. Accordingly, purposive sampling was employed based on the participants’ professional expertise and relevance to the research topic. Expert Choice software was used as the computational tool for data entry, implementation of the AHP algorithm, calculation of the relative weights of the factors, and assessment of the consistency of the judgments. Finally, sensitivity analysis was conducted to assess the robustness and validity of the AHP results. In the third stage, the prioritized factors and the relationships among them were organized and interpreted using the Driver–Pressure–State–Impact–Response (DPSIR) framework. The rationale for integrating the two frameworks was that AHP enables the weighting and ranking of factors based on the collective judgments of experts, but, on its own, it does not elucidate the relationships among the factors, their ecological consequences, or the resulting policy responses. The DPSIR framework addresses this limitation by distinguishing between structural drivers, direct pressures, the state of the system, impacts resulting from changes in system state, and management responses. Therefore, in this study, DPSIR was employed as a framework for organizing and interpreting the AHP results rather than as a quantitative model for testing causal relationships.



Results and Discussions

The results indicated that, among the seven principal criteria contributing to the decline in Lake Urmia’s water level, agricultural development ranked first, with a weight of 0.499, followed by the development of water infrastructure, with a weight of 0.244, and managerial weaknesses, with a weight of 0.120. The criteria of the construction of the causeway across the lake, climate change, urban development and human activities, and legal and institutional challenges received weights of 0.066, 0.034, 0.021, and 0.016, respectively. The predominance of agricultural development in the model indicates that the expansion of irrigated croplands and orchards, the continued cultivation of water-intensive crops, overexploitation of surface and groundwater resources, and inefficient on-farm water-demand management constitute the most important intervention domain in the Lake Urmia basin. However, this finding does not imply that drought and climate change are insignificant. Climate change can exacerbate the crisis through reductions in effective precipitation and runoff and increases in evaporation; nevertheless, under current conditions, agricultural water abstraction, relative to the remaining surface-water resources in the basin, is of decisive importance in terms of its manageability. Water-balance studies also indicate that fluctuations in lake water levels are associated with climatic drivers; however, changes in agricultural water withdrawals can either contribute to stabilizing the lake or accelerate its ecological collapse. The sensitivity analysis showed that a 10% reduction in the weight assigned to agricultural development decreased its weight from 0.499 to 0.491, while the ranking of the criteria remained unchanged. Moreover, the overall inconsistency ratios reported for the AHP structures at different levels were below 0.10, indicating an acceptable level of consistency in the pairwise comparative judgments. The DPSIR analysis revealed that agricultural development, expansion of water infrastructure, increasing water demand, climate change, and weak governance constitute the principal drivers of the crisis. These drivers exert pressure through processes such as land-use change, expansion of irrigated agriculture and water-intensive crops, over-abstraction of surface and groundwater resources, dam construction and expansion of irrigation networks, reduced hydrodynamic exchange between the two sections of the lake, and pollutant inflows. The consequences of these pressures are manifested in reduced inflows from tributary rivers, declining groundwater levels, reductions in lake water level and surface area, and increasing salinity. The ultimate impacts include habitat degradation, threats to biodiversity, expansion of salt-dust emission hotspots, salinization of surrounding soils and aquifers, adverse impacts on human health, and reduced livelihood resilience among local communities.



Conclusion:

Although managerial weakness ranked below agricultural development and water infrastructure in the AHP model, it plays a cross-sectoral and reinforcing role. Weak enforcement of environmental water rights, inconsistencies between lake-restoration policies and agricultural development policies, inadequate control over unauthorized water withdrawals, limited stakeholder participation, and the absence of clear accountability mechanisms constrain the effective implementation of technical interventions. The experience of Lake Urmia restoration programs has demonstrated that structural interventions or improvements in irrigation efficiency, in the absence of effective controls on actual water consumption, reform of economic incentives, and integrated governance, are insufficient on their own to improve the basin’s water balance. Based on the AHP–DPSIR findings, reforming the agricultural water-use system should constitute the primary axis of intervention. Nevertheless, reducing water consumption should not be reduced merely to the expansion of modern irrigation technologies, because improvements in irrigation efficiency, in the absence of restrictions on total abstraction volumes and irrigated area, may not translate into actual reductions in water consumption at the basin scale. An effective strategy should simultaneously focus on controlling water abstraction, reforming cropping patterns, restricting the expansion of irrigated land, and establishing economic and livelihood incentives for farmers.