**2. Materials and methods**

#### **2.1. Study area**

The study area is the Ariana Region, located in the north-eastern part of the Republic of Tunisia (**Figure 1**). The region occupies 482 km2 and borders Bizerte government to the north, Tunisia government to the south, Manouba government to the West and Mediterranean Sea to the East. This is the fastest growing region in the country that has experienced a significant population growth especially in the past few decades. This densely populated region (876 people per km2) includes 90.8% of its area being urban and the remaining 9.2% being rural with a total population that exceeds 510,500 people or 4.8% of the total country's population [15].

the transportation cost and need additional investments in the infrastructure of roads, hence intensify the financial problems of the responsible authorities. The estimated solid waste for the Ariana Region is 4,251,783 tons for exploitation period of 20 years. The estimate is quantified on the basis of average rate of daily waste production of 0.6 kg per capita [16]. The estimate assumes an efficiency of collecting waste of 95, and 1% of annual increase of waste production per capita per year. The estimated capacity needed for landfill area is 28 ha using

Hierarchical organization of the constraints and criteria considered for the landfill suitability is shown in **Table 1**. The top of the hierarchy is the goal while subsequent levels describe the decision or analysis criteria, the constraints and factors in increasing detail. The goal is to

In this work, the environmental, social, economic and geological information are considered to be pertinent in defining the potential sites to create a MSW landfill. In the ArcView GIS,

and cover material [17].

An Integrated Multicriteria and Fuzzy Logic Approach for Municipal Solid Waste Landfill Siting

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73

average compacted waste density of 950 kg/m3

identify the areas that are most suitable for landfill siting.

**2.2. Methodology**

**Figure 1.** Location of the study area.

The climate is Mediterranean, characterized by dry and warm summers, and cool, wet winters. The average annual precipitation is 450 mm/year and much of the precipitation falls in late autumn and early winter where the month of November has the highest precipitation while August has the lowest. The annual predominant wind direction in Ariana region is northward with an annual average wind speed of 1.5 m/s.

Currently, the MSW disposal in the region is based on landfilling in the sanitary landfill of Jebel Chakir, located 15 km to the south of Ariana city. The Jebel Chakir landfill will be closed in the near future and is too far from waste production centers in Ariana region, which increase An Integrated Multicriteria and Fuzzy Logic Approach for Municipal Solid Waste Landfill Siting http://dx.doi.org/10.5772/intechopen.75161 73

**Figure 1.** Location of the study area.

waste landfill is the site selection for solid waste disposal [1]. Landfill site selection is a complicated, complex, monotonous, requiring evaluation of various criteria. Among those criteria economic, environmental and social property are often considered for attractive the scheduling process and for setting guidelines that reduce public health risks, impact to the environment, cost to facility users and inefficiencies connected with other services [2–4]. As such, it evidently requires the processing of a massive amount of spatial data [5]. Various landfill siting techniques have been developed for this purpose. In the last few years, geographic information systems (GIS) have been increasingly used to facilitate and lower the cost of the process of selecting sites for sanitary landfills [6]. A number of GIS methods and techniques have been proposed to evaluate suitable landfill locations [1, 2, 7–9]. Some of those techniques take advantage of GIS-based multicriteria evaluation (MCE) [1, 2, 7, 8, 5, 10] and fuzzy set theory [2, 4, 11]. In MCE, the weighted linear combination (WLC) is one of the most popular methods because of its simplicity [12]. Several WLC-based approaches for landfill siting can be found in the literature [5, 11, 13]. In the WLC procedure, analytical hierarchy process (AHP) [14] is often applied to elicit criteria weights and to enhanced represent interaction between criteria and alternatives [6]. In AHP, weights are computed based on pairwise judgments and checked for consistency. Because pairwise judgments are often biased and inconsistent, acceptable consistency ratio (CR) often requires iterative revisions of the pairwise judgments

72 Fuzzy Logic Based in Optimization Methods and Control Systems and Its Applications

The purpose of this paper is to evaluate the suitability of the study region to optimally site a

The study area is the Ariana Region, located in the north-eastern part of the Republic of Tunisia

government to the south, Manouba government to the West and Mediterranean Sea to the East. This is the fastest growing region in the country that has experienced a significant population growth especially in the past few decades. This densely populated region (876 people per km2) includes 90.8% of its area being urban and the remaining 9.2% being rural with a total

The climate is Mediterranean, characterized by dry and warm summers, and cool, wet winters. The average annual precipitation is 450 mm/year and much of the precipitation falls in late autumn and early winter where the month of November has the highest precipitation while August has the lowest. The annual predominant wind direction in Ariana region is

Currently, the MSW disposal in the region is based on landfilling in the sanitary landfill of Jebel Chakir, located 15 km to the south of Ariana city. The Jebel Chakir landfill will be closed in the near future and is too far from waste production centers in Ariana region, which increase

population that exceeds 510,500 people or 4.8% of the total country's population [15].

and borders Bizerte government to the north, Tunisia

landfill for MSW Ariana using AHP and WLC in a GIS environment.

before the final weights are computed.

**2. Materials and methods**

(**Figure 1**). The region occupies 482 km2

northward with an annual average wind speed of 1.5 m/s.

**2.1. Study area**

the transportation cost and need additional investments in the infrastructure of roads, hence intensify the financial problems of the responsible authorities. The estimated solid waste for the Ariana Region is 4,251,783 tons for exploitation period of 20 years. The estimate is quantified on the basis of average rate of daily waste production of 0.6 kg per capita [16]. The estimate assumes an efficiency of collecting waste of 95, and 1% of annual increase of waste production per capita per year. The estimated capacity needed for landfill area is 28 ha using average compacted waste density of 950 kg/m3 and cover material [17].

#### **2.2. Methodology**

Hierarchical organization of the constraints and criteria considered for the landfill suitability is shown in **Table 1**. The top of the hierarchy is the goal while subsequent levels describe the decision or analysis criteria, the constraints and factors in increasing detail. The goal is to identify the areas that are most suitable for landfill siting.

In this work, the environmental, social, economic and geological information are considered to be pertinent in defining the potential sites to create a MSW landfill. In the ArcView GIS,


• The WLC aggregation method was applied for preparing the suitability maps. Suitability maps for each set of factors were combined to create three scenarios to allow determination

An Integrated Multicriteria and Fuzzy Logic Approach for Municipal Solid Waste Landfill Siting

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• The landfill suitability is classified in five equally scored classes: high, suitable, moderate,

The exclusion criteria are constraints having for objective to limit research of suitable sites

The classification consists in selecting various areas that represents a new plan of information for a required condition. Maps were classified into two categories: 1 was ranked to zones verifying the condition and 0 was ranked to the other zones. The resulting image is a Boolean

The last step consisted in combining, by superposition, the information contained in Boolean layers relative to the exclusion criteria mentioned above. The logical operator "AND" has been used in this part; it translates the intersection between conditions that must be absolutely satisfied.

MCE requires that the values contained in the different criterion map layers be transformed to similar units [11]. A number of approaches can be used to make criterion map layers comparable. The fuzzy membership approach is one of the standardization methods that have been proposed [10]. For this reason, fuzzy sets were used in this study. To apply fuzzy functions in the GIS environment in this case study, all the map layers are transformed to a raster format with 100 m pixel size. Four fuzzy set membership functions are provided in IDRISI: Sigmoidal, J-Shaped, Linear and User-defined. Our choice has been made relying on two types of factors (environmental and socio-economic) that have been standardized in one com-

The purpose of criterion weighting is to express the importance of each criterion relative to other criteria. One of the techniques that can be used in assigning weights is Pairwise Comparisons (that characterizes analytic hierarchy process: AHP, developed by Saaty [18]; it determines accurate relative weights of indicators by allowing to divide the complex decision problem into a series of one-on-one judgments regarding the significance of each criterion

of the most suitable sites.

image.

low and very low suitability areas

which do not tolerate any competition [10].

**4. Standardization of appreciation criteria**

mon interval from ranging from 0 to 10.

relative to the others.

**5. Weighting factors for aggregation**

**3. Classification of exclusion criteria (constraints).**

**Table 1.** Hierarchical structure for the selection of the MSW landfill site.

all the thematic maps were transformed on raster grid to be used by Idrisi software. A raster grid cell of 100 × 100 m2 was generated. Each cell is considered as a homogenous unit for any given factor. All the factors influenced were standardized and weighed and then combined using the AHP methods.

The site selection process is implemented in the following steps:

