Water is pivotal to environmental sustainability and economic development. Rapid population growth and the escalating demand for reliable resources have intensified the need for desalination facilities. Given Iran's strategic geopolitical position, these critical infrastructures necessitate design frameworks grounded in passive defense principles to mitigate potential security, economic, and social disruptions. This study identifies and analyzes passive defense requirements in desalination plant design using Q-
methodology. This applied research employs a descriptive-analytical approach within a mixed-method framework. Initially, 37 statements were extracted as key indicators through a literature review and expert consultations. Subsequently, these statements were ranked by participants using the Q-sort technique, and data were processed using SPSS via exploratory factor analysis .The analysis identified four dominant mental models, further categorized into 20 principal factors. The findings reveal that critical requirements including camouflage and concealment, structural configuration, material durability, structural strengthening, optimal site selection, and early warning systems are essential for resilient design. Ultimately, integrating passive defense principles with engineering design significantly enhances the resilience and security of these vital infrastructures, ensuring sustainable water resource management during crises.

Introduction:
Water holds a sacred and strategic status in Iran’s history and culture. Its vital role in sustaining human life and its impact on national security have rendered water infrastructure a cornerstone of societal stability. In the 21st century, escalating water stress and climate change have transformed access to sustainable freshwater into a preeminent global challenge for national security and environmental sustainability. Given the depletion of surface and groundwater resources in arid and semiarid regions, water desalination technologies have emerged as a fundamental strategic solution for providing potable and industrial water. However, the high concentration of capital and advanced technology within these facilities makes them soft targets in modern warfare doctrines and terrorist agendas. Any operational disruption can trigger irreversible social, security, and economic crises .
Methodology:
This study employs Q-Methodology, a research framework designed to systematically study human subjectivity and prioritize diverse perspectives through the correlation of respondent viewpoints. Unlike traditional R-
methodology which focuses on variables, Q-
methodology facilitates the identification of shared mental models and discourse patterns among participants.
A purposive sampling technique was utilized to select 25 experts, including academics and industrial specialists in desalination and passive defense. Ultimately, 15 participants completed the Q-sorting process due to the rigorous and time-consuming nature of the tool. The participant pool consisted of 8 Ph.D. holders (53.3%), 3 doctoral candidates (20%), and 4 senior technical consultants from desalination investment firms (26.7%)
Participants ranked a set of Q-statements onto a quasi-normal distribution grid based on their degree of agreement. The resulting data matrix was analyzed using SPSS software. To identify the underlying mental patterns (subjective factors), Principal Component Analysis (PCA) was performed, followed by Varimax Rotation to enhance the interpretability of the factors. This rigorous statistical approach ensured that the identified perspectives were both distinct and representative of the experts' collective intelligence.
Results and discussion:
The Q-factor analysis yielded four distinct mental models (factors), collectively accounting for 78.825% of the total variance, which indicates high statistical reliability and strong explanatory power. These factors encapsulate the consensus among experts regarding the critical requirements for passive defense. The results emphasize several core components:
1. Structural Fortification and Resilience: Ensuring the integrity of critical facilities under crisis conditions.
2. Strategic Siting (Location): Integrating defensive and environmental considerations into the initial site selection process.
3. Early Warning Systems: Designing efficient and rapid response systems to detect threats.
4. Infrastructure Interdependency Management: Mitigating the risks associated with reliance on external power grids and other critical utilities.
5. Camouflage and Concealment: Implementing innovative methods to reduce the signature of the facilities against modern reconnaissance.
The innovation of this research lies in its ability to formulate these subjective expert insights into a structured framework, moving beyond traditional technical parameters to include geopolitical and security-centric resilience.
Conclusion The primary innovation of this research lies in the application of Q-factor analysis as a robust tool to decode and categorize the specialized perspectives of stakeholders and experts in passive defense and water engineering. Unlike traditional research methods that focus solely on external variables, Q-methodology facilitated the systematic formulation of subjective factors and mental patterns. This approach enabled the researchers to reveal the hierarchy and spectrum of existing viewpoints regarding passive defense priorities in desalination facilities through a structured, quantitative lens.
This methodological framework provides a deeper understanding of the security challenges and offers operational solutions tailored to field realities. By synthesizing these expert mental models, the study strengthens the validity of the identified requirements ranging from structural fortification to strategic siting. Ultimately, the findings establish a comprehensive framework that guides policymakers and engineers in enhancing the resilience of critical water infrastructures against a wide array of contemporary threats. This research ensures that passive defense considerations are no longer secondary add-ons but are integrated into the core strategic planning of sustainable water systems.
Funding:
There is no funding support.
Authors’ Contribution:
Authors contributed equally to the conceptualization and writing of the article. All of the authors approved thecontent of the manuscript and agreed on all aspects of the work declaration of competing interest none.
Conflict of Interest:
Authors declared no conflict of interest.
Acknowledgments:
We are grateful to all the scientific consultants of this paper.