Evaluating the Influential Indicators of Urban Agriculture with the Approach of Nature-Based Solutions to Deal with Urban Challenges

Introduction
Urban environments are increasingly vital for supporting society in terms of economy and ecosystems. According to estimates by the United Nations, the global population is expected to reach approximately ten billion by 2050. The density of populations in compact cities gives rise to urban challenges, including economic, social, and environmental issues. On the other hand, these challenges have prompted humanity to reconsider its relationship with nature, leading to various efforts in this direction. Green infrastructure is one of the most significant strategies employed to address urban challenges. Among the most effective subsets of green infrastructure is urban agriculture. In response to the growing urban population, the Food and Agriculture Organization (FAO) has introduced urban agriculture (UA) as an effective solution, as UA has the potential to create cities rich in green spaces and productive in food resources. Urban green spaces, such as urban agriculture, can reintegrate diverse green infrastructure into urban systems, providing a vegetative structure and biodiversity essential for ecosystem functioning and services across habitats and spaces. Recognizing the crucial role that green infrastructure and its ecosystem services play for the environment and communities, the Directorate-General for Research and Innovation of the European Commission has recently introduced the concept of Nature-Based Solutions (NBS). Focusing on the multiple co-benefits for the environment, economy, and society within urban landscapes, NBS can offer more efficient and cost-effective solutions compared to traditional development approaches. The International Union for Conservation of Nature defines nature-based solutions as actions to protect, sustainably manage, and restore natural or modified ecosystems. Nature-based solutions address social challenges such as climate change, food and water security, or natural disasters while providing services to humanity. Implementing innovative NBS requires integrated assessments conducted through indicator evaluations. This study examines the impact of common indicators of nature-based solutions and urban agriculture on urban challenges.
 
Methodology
This research was conducted using a questionnaire tool among experts (the Delphi method) and employed the Friedman test for analysis. SPSS software was utilized to analyze the findings. The Delphi method aimed to achieve a consensus opinion from a group of experts on a specific topic or question and is often used in situations where there is limited or conflicting evidence, especially when participants may be geographically dispersed. Therefore, the Delphi panel in this study consisted of 16 experts with professional or academic backgrounds who responded to 33 questions related to urban agriculture indicators and nature-based solutions using a Likert scale. To determine the level of agreement among group members, Kendall's coefficient of concordance was used, and the Delphi decision-making method was carried out in two phases. The objective of multiple iterations in the Delphi method is to narrow the range of responses and achieve expert consensus, which is often more reliable than individual guesses or opinions. After ranking through the Delphi method, the Friedman test was used to rank the indicators, and the results of both methods were subsequently compared.
 
Findings
The findings from the Delphi phases indicate a positive impact of educational and aesthetic indicators, as well as biodiversity, on urban agriculture. Due to the differing mathematical formulations of the Delphi method and the Friedman test, the Friedman test identified biodiversity, education, welfare, and tourism as the most influential indicators, respectively. In the first phase of the Delphi method, the social justice indicator did not achieve the necessary score and was removed from the list of indicators relevant to urban agriculture. In both methods, the social justice indicator had the least impact on urban agriculture. Comparing the findings from both methods revealed that the most influential indicators on urban agriculture are those common to both urban agriculture and Nature-Based Solutions.
 
Discussion and Conclusion
The results of the study highlight the multiple benefits of urban agriculture, which has significant potential for economic empowerment and social and environmental sustainability. Among the variables examined in this study, education, food security, biodiversity, and aesthetics were identified as the most influential variables, respectively. Thus, urban agriculture is considered a flexible and cost-effective solution that addresses a wide range of urban challenges while providing extensive benefits for citizen well-being and serving as a nature-based solution for sustainable urban development in response to urban challenges.