The importance of sustainability was magnified and gained a heightened sense of urgency around the world after the Our Common Future (Brundtland Report) was released in 1987 by the World Commission on Environment and Development (WCED) (Łozowicka 2020). From the discovery of agriculture to the present day, the ability of mankind to transform and reorganize the tangible world peaked with the Industrial Revolution. Although the devastating effects of this Revolution, which began in the second half of the 1700s, was discovered early on, it was not until the 1900s that people realized how the enormous amounts of pollution put species and environments at risk. By the late 20th century, pollution was at such high levels around the world that major counteractions were required.
The excessive overconsumption of resources following the Industrial Revolution, the tradition of manufacturing and accumulating a surplus of product, as well as unconsumed products becoming residual were the critical factors leading to the concept of sustainability. Once people took notice of the adverse consequences of those actions and their reliance on irreversible consumption, the concept of sustainability was taken into more serious consideration by multiple disciplines, including social, cultural, and financial. Ever-growing consumption not only caused a rapid depletion of global resources but also negatively impacted financial institutions, companies and organizations, culture, environment, population, etc. This is accurately summarized by Egger (2006) with the rise of overconsumption, a decline in the carrying capacity of the world will be observed.
The term ‘sustainability’ appears to be a complex concept with no clear definition (Azapagic and Perdan 2000, p. 243; Egger 2006; Vesela Veleva and Ellenbecker 2001, p. 519); however, the term should be clarified and developed (Vesela Veleva and Ellenbecker 2001). The nature of the term ‘sustainability,’ implies that it must be in a constant state of transformation (Łozowicka 2020, p. 2). Due to the fact that this term is multifaceted, defining it succinctly has proven complicated. However, sustainability must become one of the main paradigms if we are to continue to advance society and maintain diversity (social, cultural, financial, etc.) for future generations.
Sustainability, therefore, requires the consideration of the future. Most importantly, industrial businesses must adopt sustainable manufacturing systems (Azapagic and Perdan 2000, p. 243; Krajnc and Glavič 2003, p. 280); this necessitates robust top management, government support, and high consumer motivation (Vesela Veleva and Ellenbecker 2001, p. 532). Demanding the renewable use of resources is also of utmost importance (Rosenberg et al. 1993, p. 828). Veleva et al. (V Veleva et al. 2001, pp. 451–452) noted that the manufacturing aspect of sustainability is based on minimal material use, ecologically-minded manufacturing, minimal packaging, and recycling. With this being the case, another factor that must be taken into account is the fact that sustainable manufacturing is not simply about the use of minimal raw materials and environmentally-friendly production processes. To achieve sustainability in true sense, manufacturing must not only generate less waste but also ensure that the waste from finished products have some level of value and can be recycled.
During the United Nations Conference on the Human Environment—which was held in 1972 in Stockholm—the United Nations Environment Programme (UNEP) which intended to achieve and monitor environmental protection was approved. Raising further awareness about sustainability and examining the concept of sustainable development, Our Common Future (Brundtland Report) by the WCED was released in 1987. Then in Rio de Janeiro in 1992, at the United Nations Conference on Environment and Development (UNCED), also called the Earth Summit, the attention of the world was again placed on sustainable development. One of the outputs from this conference, known as Agenda 21, has grown into a major landmark concerning its sustainable development program (Łozowicka 2020, p. 1), especially since the concept of sustainability penetrates into almost every activity from production to consumption, particularly from an environmental point of view. As noted by Azapagic & Perdan (Azapagic and Perdan 2000, p. 243), world governments developed sustainable development strategies covering the items of Agenda 21.
Since then, 17 Sustainable Development Goals (SDGs) have been introduced by the United Nations Security Council. To offer a solution to the many problems modern society faces, as noted by García-Feijoo (García-Feijoo et al. 2020, p. 1) the 2030 Agenda was assembled between 2000 and 2015 as a part of the UN Millennium Development Goals. These 17 SDGs, which include 169 associated targets and serve as an outline until 2030, were ratified by world governments (García-Feijoo et al. 2020, p. 1; Modibbo et al. 2020; “Sustainable Development Knowledge Platform” n.d.). The fact that the 21st century includes sustainability in every aspect of life, it has become the most important philosophy at the start of this millennium.
As we look at these 17 goals, a wide range of topics are represented—from the economy, education, and health to energy and the environment. A list of the SDGs are as follows: (1) No Poverty; (2) Zero Hunger; (3) Good Health and Well-being; (4) Quality Education; (5) Gender Equality; (6) Clean Water and Sanitation; (7) Affordable and Clean Energy; (8) Decent Work and Economic Growth; (9) Industry, Innovation, and Infrastructure; (10) Reducing Inequality; (11) Sustainable Cities and Communities; (12) Responsible Consumption and Production; (13) Climate Action; (14) Life Below Water; (15) Life On Land; (16) Peace, Justice, and Strong Institutions; (17) Partnerships for the Goals (United Nations n.d.).
Sustainability and Landfilling
Leading a responsible life from a sustainable perspective requires mankind to consider the physical limitations of nature on this planet (Klitgaard 2020, p. 2). Since humanity is polluting the world with what they have consumed, not considering future consequences of those actions, and pushing the limits of nature to its furthest the need to develop methods for sustainable waste management has become essential. As noted by Tchobanoglous et al (2002, p. 1.11), landfilling is the least desirable stage of waste management yet it is also currently the most advantageous for all stakeholders.
Sustainable waste management influences the relationship between nature and humanity in three main areas: ecology, economy, and society (Rodić and Wilson 2017). Additionally, health costs and government regulations could also be added to this list (Siddiqui et al. 1996). Waste management was also emphasized as an important factor for ecology and environment in Agenda 21 (“Waste management” n.d.). For this reason, environmental issues have become some of the most important points in the SDGs. One of the first steps to be taken for environmental protection is to determine how to best manage waste that has been generated out of consumption. Although some of the SDGs are only slightly related to waste management, studies show that 12 SDGs (nearly all of them) have some relationship to landfilling (Rodić and Wilson 2017). In addition, some of the goals pertain directly to waste management such as (3) Good Health and Well-being; (6) Clean Water and Sanitation; (9) Industry, Innovation, and Infrastructure; and (11) Sustainable Cities and Communities. For example, the SDG of (3) Good Health and Well-being specifies that waste must be properly stored, the utmost attention should be paid to natural and human characteristics during landfill site section, and ensures that no risk is posed to human health. If there is any failure in designating a proper landfill site such as not taking into account the ground characteristics of the landfill or its proximity to surface waters and rivers; the risk of contamination to drinking and utility water increases. Contaminated water from landfill leakage could extend beyond is original region if that same polluted water is used for irrigation purposes.
Recently, it has become more popular for research studies to focus on the future of smart cities and their management. Smart cities employ systems and technologies for infrastructure and superstructure which facilitates a more comfortable urban life. While automated systems provide more convenience, they also involve long-term projections and advanced planning. Accordingly, the site selection for landfills has become even more important. Having a rational discussion about urban management could not be plausible without also addressing waste management and the factors that influence its site selection, including air pollution, foul odor, visual pollution, and damages that could be caused to infrastructure. In fact, the collection of waste from urban settlements as well as the way in which waste is handled and separated will undoubtedly be automated and sustained as a part of any smart city in the near future. However, the top priority for such an automated system is the selection of a landfill site location which ensures that automated systems are able to function smoothly. Since it would not be possible to relocate an unsuitable landfill, the desired outcomes would fail to be achieved. Therefore, one of the most important steps in waste management, which relates to most of the SDGs, is the location selection of landfill sites.
While waste management and related matters have been historically acknowledged as engineering challenges, many disciplines are now taking an interest in this topic due to its multidimensionality and challenges outside of the environmental issues that are caused by waste (Kaplan Mintz and Kurman 2020; Tchobanoglous et al. 2002, p. 1.1–1.2). The fact that waste management has expanded beyond simply being a waste problem and has assumed both social and economic dimensions, has led a variety of disciplines to research the issue.
Excessive waste generation caused by population growth puts more pressure on the planetary ecosystem. This increase in waste generation has made it imperative to develop ways to contend with waste materials. Egger (2006, p. 1236) argues that the impact of waste generated by humans has a greater influence on the world than does the rising growth rates of the human population. However, altered consumption patterns coupled with rising amounts of waste from that growing population, exacerbates the generation of waste even further; statistics clearly reveal the extent of this increase. For instance, the amount of urban solid waste per capita in the United States, the world's top economic power, was 1.2 kilograms in the 1960s while it amounted to 1.9 kilograms in the 2000s (Tchobanoglous et al. 2002, p. 1.3). Given the fact that the global population was nearly 3 billion in the 1960s and is now nearly 7.5 billion, it is clear to see how profoundly the amount of waste has increased. As Zhu (Zhu et al. 2020) stated, waste generation is at an alarming level, especially in countries with intense industry such as China. Whether waste is solid or liquid, still one of the most important aspects of waste management is the site selection for landfills—which requires substantial expertise.
According to the U.S. Environmental Protection Agency (EPA) there are four stages of managing waste within the Integrated Waste Management Plan. The first of these is (1) Source Reduction, mainly aiming to reduce the amount of waste and toxicity. (2) Recycling and Composting is another strategy that reclaims reusable materials from waste. Once the amount of waste has been reduced, it can then undergo (3) Combustion or Waste Transformation to generate energy. (4) Landfilling is the final and least desirable option (Tchobanoglous et al. 2002).
Various methods have been adopted to designate locations for landfilling in Turkey. For this purpose, from a methodological standpoint fuzzy logic (Özdemir Kipel 2017) multi-criteria decision making, analytical hierarchy (Ersoy 2007), and scoring have been used. In Turkey, the number of studies that have adopted geographical information systems (GIS) has been increasing in recent years. These studies, which employed GIS, were conducted in an effort to designate eligible landfill site locations across different provinces of Turkey: Konya, Gaziantep, Samsun, Adana, Uşak, Şırnak, Afyonkarahisar, Antalya, Isparta, İstanbul, İzmir, Sivas, Trabzon, Ankara, and Kahramanmaraş (Kaplan 2002; Şener 2004; İşlek 2004; Nas et al. 2009; Deniz and Topuz 2018a; Karayılan 2018; Aksoy 2016; Dağıstanlıoğlu 2012; Kavaklı 2011; Bahçeci 2006; Coşkuner 1996; Yildirim 2012; Güler 2016; Kolay 2012; Öner 2019; Erdoğan 2019; Küçükönder and Karabulut 2007; Özdemir Kipel 2017; Ersoy and Bulut 2009).
In this research field, problems concerning the location of landfill sites continue to arise. Following an environmental disaster in the district of Merkez, retrospective research was conducted and the location of a landfill was, indeed, cited as a problem (Deniz and Topuz 2018a). After the destruction of one of the wastewater treatments plants, over pollution of nearby rivers, pollution caused by industrial zones as well as facilities where urban waste is stored, and air pollution from significant industrial production the critical issues Uşak must address were exposed. The preferences for the location of landfill sites for this province had become such an issue that they were reported by the local and national Turkish press, which led to some landfills being relocated multiple times. Issues still persist despite the relocation of landfill sites and treatment plants around Uşak province because their locations were not properly selected, which is now evident. This is an example of why the proper designation of a location, by means of strictly-designated variables, is of the utmost significance, especially when considering the health and environmental problems imposed on the surrounding population. In order for Uşak to achieve some of the SDGs (Good Health and Well-being; Clean Water and Sanitation; Industry, Innovation, and Infrastructure; Sustainable Cities and Communities), the location of landfill sites must be properly designated in accordance with scientific criteria.
The intention of this study is to accurately identify eligible landfill site locations for sustainable waste management across the province of Uşak, while taking into account the literature from the field and the unique, local geographical factors. The entire province of Uşak was surveyed in order to determine the potential landfill site locations using GIS. If the designated locations could be fully evaluated in coordination with regional zone planning, the health and environmental problems could be mitigated or prevented entirely, thus, making this study imperative.
Location and general geographical features of research area
The country of Turkey consists of 81 provinces that serve as local authorities. As a part of the administrative structure, the provinces are then divided into districts that serve as small-scale authorities. The Aegean region contains 11 of those provinces, of which the study area is one: Uşak province is located in the inner-western Anatolian sub-region. This province is surrounded by Kütahya to the north, Afyonkarahisar to the east, Denizli to the south, and Manisa to the west (Fig. 1). According to the General Directorate of Mapping, it has a total territorial size of 5555 km2 (Harita Genel Müdürlüğü 2020).
Within Uşak province, the unpredictable Mediterranean climate is prevalent across lower elevations while a continental climate prevails across the higher elevations. This area is hydrographically home to the headwater springs of many rivers since it is located in a higher region of western Anatolia. Situated in the northern part of the province is Murat Mountain, which is where the upper basins of Büyük Menderes, Gediz, Sakarya, and Akarçay rivers are located.
Uşak province is home to 6 total districts—Banaz, Eşme, Karahallı, Sivaslı, Ulubey, and Merkez; the final location is located in the center of the province, which is also its administrative center (Uşak City). Before 1953, the different territories of Uşak province had been designated to the neighboring provinces of Manisa and Kütahya. Due to the introduction of a new law in that same year, the province of Uşak was founded. Uşak province currently has a total of 251 administrative offices, including 245 rural ones and 6 urban ones. In 2019, the total population of the province was 370,509—where 278,806 resided in urban areas and 91,703 resided in rural areas(TÜİK 2021). The main economic sector for urban areas is the service industry while rural areas generally rely on agriculture and animal husbandry. However, heavy industry constitutes as a major economic activity, and three organized industrial zones are located close to the district of Merkez.