Assessment of Drinking Water Resources Resilience in Yazd City Using the Delphi Method

Abstract
Objective: The quantitative and qualitative decline of water resources represents a critical global challenge, necessitating in-depth investigation in regions susceptible to water scarcity. Yazd city, characterized by a hot and arid climate, falls into this category. Resilience, defined as the ability of a system to withstand disturbances and maintain functionality, plays a pivotal role in sustainable water resource management. This study aimed to assess the resilience of drinking water resources in Yazd city, identifying its strengths and weaknesses.
Method: Employing a practical, descriptive-analytical approach, data were collected through literature review and field studies, utilizing the Delphi method with the participation of 40 experts in water resources, environmental science, and urban management. The Delphi process facilitated consensus among experts regarding factors influencing resilience and the evaluation of the current situation. Data analysis was performed using SPSS software.
Results: The findings indicate an unfavorable assessment of drinking water resource resilience across all investigated dimensions. Specifically, the dimensions of "Current Drinking Water Status and Supply" and "Future Drinking Water Quality" exhibited the lowest scores, with means of 2.10 and 2.13, respectively, indicating significant challenges in ensuring sustainable and high-quality drinking water provision.
Conclusion: These results highlight the high vulnerability of Yazd's drinking water resources to climate change and increasing demand. Consequently, the sustainability and resilience of drinking water resources in Yazd city require urgent attention and immediate measures to prevent potential crises. 
 
 
 
English Extended Abstract
Introduction
Iran is classified as part of the world's arid regions due to its low average rainfall and the uneven spatial and temporal distribution of precipitation. Under such conditions, the effective management of water resources in Iran is imperative. The city of Yazd, selected as the case study in this research, faces chronic water scarcity and challenges in securing reliable water sources. Therefore, the concept of resilience in the context of water resources requires thorough investigation and evaluation.
This study seeks to answer the following question: To what extent are Yazd’s drinking water resources capable of withstanding consumption pressures, considering various factors such as declining precipitation, increased evaporation and transpiration, and excessive water withdrawals?
The objective of this applied research is to assess the resilience of Yazd’s drinking water resources and identify their strengths and weaknesses. The research adopts a descriptive-analytical methodology. Data collection was conducted through both documentary review and fieldwork, utilizing the Delphi method with the participation of 40 experts specializing in water, environmental science, and urban management. The Delphi process was employed to reach expert consensus on the key factors influencing water resilience and to evaluate the current status of water systems in Yazd.
 
Method
To collect the required data, this study employed a mixed-method approach combining documentary and field techniques. The literature review and investigation of the geographical characteristics of the study area—Yazd, Iran—were conducted through desk research. Population data, water consumption patterns, and expert insights were obtained via fieldwork, including interviews and structured questionnaires.
The statistical population of this study consisted of specialists and professionals in the field of drinking water resources in Yazd. Due to the specialized nature of the target group, a sample size of 40 participants was determined and selected using the snowball sampling method. In this technique, experts contributed to sample expansion through reciprocal introductions.
Data collection was facilitated using a questionnaire designed based on a Likert scale. The items were formulated with reference to prior studies and expert opinions. The collected data were analyzed using SPSS software and interpreted through the Delphi model. The key evaluation criteria included water quality, water quantity, resource capacity, and consumption patterns.
The Delphi method—recognized for its validation capability and expert consensus-building—was applied to synthesize professional perspectives and guide informed decision-making on key components of the issue under investigation.
To quantify qualitative data obtained via the Likert-based questionnaire, numerical values ranging from 1 to 5 were assigned to each response, corresponding respectively to "very poor," "poor," "moderate," "fairly good," and "excellent." After the first round of questionnaires, the mean and standard deviation for each item were calculated. Additionally, Kendall’s coefficient of concordance (W) was employed to measure the degree of agreement among experts. Values approaching zero indicated minimal consensus, while values nearing one suggested strong agreement. Given that complete consensus (100%) is rarely attainable, a threshold of 0.7 was set as the benchmark for acceptable agreement. Accordingly, Kendall values below 0.7 indicated the need for subsequent Delphi rounds, whereas values above 0.7 were deemed indicative of sufficient expert consensus.
 
Results
Yazd faces critical urban water supply challenges due to rising per capita consumption, limited accessible resources, and increased migration. The city operates 13 water storage tanks, six of which are active with a nominal capacity of 113,000 m³; seasonal fluctuations reduce reservoir levels to 50–60% capacity. Drinking water is sourced from groundwater and transferred through supplies. Statistical analyses revealed strong positive correlations between population growth and water consumption (Pearson’s r = 0.951 and 0.991). Projections indicate escalating demand amid population pressures, while expert interviews highlight limited resilience, with quality storage capacity estimated at just 48 hours in emergencies.
The Delphi method was used to assess expert consensus regarding water system indicators. The first round produced low agreement (Kendall’s W ≈ 0), prompting a second round with a 95% response rate. The resulting W = 0.719 reflected substantial convergence, negating the need for further rounds. While water use patterns showed moderate adequacy (average score ≈ 3), indicators related to consumption levels and resource capacity were deemed suboptimal, emphasizing the urgent need for effective improvement strategies.
 
Conclusion
Based on expert interviews, data analysis, and the Delphi process, the resilience status of drinking water resources across all relevant indicators was evaluated as unfavorable. The Delphi results highlight significant challenges in terms of water quantity, quality, ecological potential, and sustainability indicators.
Item analysis revealed that the lowest scores were associated with statements on the "current status of drinking water supply" (2.10) and the "future quality of drinking water" (2.13), whereas the highest scores were attributed to "drinking water conservation practices" (3.08) and "water consumption culture" (3.05).
It is noteworthy that the city's drinking water supply is heavily reliant on transferred water sources, as existing local resources are insufficient in both quantity and quality to meet citizens' needs. Population growth and increasing migration further intensify water demand, placing additional pressure on available resources.
Given these circumstances, relevant authorities must adopt strategic approaches and develop practical solutions to ensure the sustainable management and provision of water resources—both now and in the future. Water, after all, is the foundation of life and sustainable development.