Digital Mapping and Spatial Analysis of Quarries Using GIS – A Case Study of Settat Province, Morocco

The province of Settat plays a key role in supplying the building materials that meet the needs of the province as well as the provincial construction and public work sectors. Indeed, the province is full of natural potential in raw materials and counts more than 109 quarries. This study aimed to build a quarrying database in the province of Settat to both characterize the materials mined and map the quarries through the Geographic Information System (GIS). This mapping allowed conducting the geographical distribution analysis of quarries by territorial unit and type of materials. The results revealed a predominance of carbonate quarries, especially in the Ben Ahmed circle. This distribution can be explained by natural, economic, and logistical factors characterizing the study area.


INTRODUCTION
The province of Settat is located in the center of the Kingdom. It is part of the Casablanca-Settat mega-region; this region is characterized as the country's first multi-sector economic hub. The province is bounded to the north by the provinces of Berrechid and Benslimane, to the south by the provinces of Kalla-Sraghna and Rhamna, to the east by the provinces of Khouribga and Fqih Ben Salah, and the west by the province of El Jadida. The province covers approximately 7220 km 2 , which represents 35% of the regional area [Ministry of the Interior, Wilaya of the Chaouia Ouardigha Region, Settat Province, 2013].
It comprises five urban communes and 41 rural communes grouped in three circles (Table 1) [Direction Provinciale de Settat, 2016]. The province is characterized by a semi-arid climate in the north, shifting to an arid climate in the south; the average rainfall is about 378.8 mm/year. Geologically ( Figure 1) [Bolelli, et al. 1959;Gigout, et al. 1965; Institut Géographique National (France), Gigout, 1954], the province belongs to the structural domain of the Moroccan Meseta, characterized by a Paleozoic basement peneplain surmounted by a tubular alpine cover. It is bounded to the northwest by the coastal Meseta, to the southwest by the Rhamna Massif, and to the east by the phosphate plateau [El Bouqdaoui, 1995].
A certain physical homogeneity characterizes the territory of Settat province. Indeed, two distinct zones can be indicated: the lower Chaouia, an area of Tirs soils, and the upper Chaouia, characterized by a gradual decrease in fertile land; it is constituted of limestone plateaus of a rugged landscape, reinforced by phosphate layering [Icole, 1964].
The analysis of the digital terrain model of the province ( Figure 2) shows a decreasing topographic gradient from east to west, varying between 870 m and 15 m: • At the coastal Meseta, altitudes range from 15 m to 300 m.
The exploitation of quarries has many impacts on the environment: irreversible soils and subsoil degradation (stripping, extraction, felling, earthworks, etc.), changes in landscapes and natural habitats, impact on biodiversity, dust emissions, vibrations and noise (explosives), greenhouse gases (transportation) or suspended materials (water resources) release, etc.
Due to the absence of an efficient legal framework before the release of Law No. 27-13 of June 9, 2015, relating to quarries [Dahir N. 1-15-66 of June 9, 2015 (21 Shaaban 1436) Promulgating Law N. 27-13 Relating to Quarries, 2015], the quarry sector has recently experienced dysfunctions concerning the modes of exploitation and the emergence of informal quarries, as well as the looting of materials and the ineffective control, which has had adverse effects on the population, the natural environment, the infrastructure, as well as the financial income [The Economic, Social and Environmental Council, 2014; Majdoubi, 2016] .
The goal of this work was to perform a situational analysis of the extraction of different materials in the province through [Aboutayeb, et al. 2013;Attima, et al. 2016]: • the creation of a geographical database (Geodatabase) on opencast quarries in the province of Settat; • the mapping of opencast quarries by material type and by commune using GIS; • the analysis of the geographical distribution of the various opencast quarries.

MATERIALS AND METHODS
The data on open-pit quarries in the province of Settat comes from the inventory of quarries in the province conducted at the end of 2018 [Ministry of Equipment, Transport, Logistics and Water, Directorate of Administrative and Legal Affairs, 2018].
All the mapping work was carried out using the ArcGIS 10.5 software. The ArcGIS 10.5 software combines most of the functionalities related  to GIS. When used alone or combined with other applications, it can help conduct a project from data acquisition to presentation. Digitization, database management, spatial analysis, thematic mapping, and layout are tasks that can be carried out with ArcGIS 10.5. There are two base maps used for these map representations. They showcase the boundaries outline of the three circles that make up the province of Settat. The boundaries of 46 provincial communes are also showcased.
The cartography was carried out by combining objects with spatial references and their attributes; it was necessary to link the attributes of quarries with the geographical references of each commune. The Geodatabase in question included two types of information: • Attributes or alphanumeric information: this is the information collected from the administration regarding the type of material, area, and coordinates (X and Y); • Geographical information on the territories of each commune.
A legend was built to demonstrate the proportional size of the number of quarries connected to each commune on the map. Most of the time, each card corresponds to a single field of activity. However, sometimes several neighboring areas are grouped on the same map. A scale to measure the distance from the province territory is expressed in kilometers.

RESULTS AND DISCUSSION
The database reported the distribution of quarries in the province of Settat by circle (Ben Ahmed, Settat, and El Broj) and by commune, while specifying the number of units, production capacity, and material type: carbonates, clays, pit-run gravel, massive gravel, alluvial aggregates, and shale. Figure 3 shows the distribution of 109 quarries by material type in the three circles of the province. The analysis of this figure shows: • The dominance of Ben Ahmed's circle with 92 quarries, equivalent to 84% of quarries within the province, followed by the circle of Settat with 11 quarries and the circle of El Broj with only six quarries; • The dominance of carbonate quarries with 58 quarries, representing 53% of quarries within the province and 63% of the Ben Ahmed's circle quarries. Settat's circle has only one quarry of carbonates; • The 16 clay quarries are in the Ben Ahmed's circle; • Alluvial quarries are mainly in the circle of El Broj with six quarries. The Settat's circle has only one alluvial quarry; • Massive gravel production is concentrated in the Ben Ahmed's circle with 11 out of 13 quarries in the province. The other two quarries are in the Settat's circle; The spatial distribution of quarries represented in Figures 4 and 5 showed that the highest concentration of quarries is in the commune of Ain Dorbane-Lahlaf with 32 quarries, followed by the communes of Bouguergouh, Lakhzazra, M'Garto, and Sidi Dahbi, with an average number ranging between 9 and 16 quarries. The rest of the communes have a very low number of quarries, between 1 and 8 quarries.
The spatial distribution of quarries by material type is illustrated in Figure 6, which shows: • Alluvial gravel production (Figure 6a) is dictated by the Oum Errabiâ, which is a natural boundary between the province of Settat and the province of Rhamna. The province counts seven alluvial quarries distributed as follows: three quarries in the commune of Oulad Amer, and one quarry per commune in Ain Blal, Laqraqra, Oulad Freiha, and Machraa Ben Abbou; • The production of massive gravel (Figure 6b) is determined by the proximity of consumption sites, which explains the exploitation of  The capacities of quarries vary in terms of production, ranging from one thousand m 3 to more than one million m 3 of material production per commune. For this reason, GIS was used to map the production capacity in the province of Settat by material type (Figure 7).   • The production of marble amounts to 11750 m 3 /year, on two communes. The analysis of Figure 7g shows a very high production in the commune of Oued Naanaa of around 10750 m 3 /year over an area of 44425 m 2 ; • The cut stones production is located only in the commune of Gdana with a production capacity of 600 m 3 /year on an area of about 30000 m 2 (Figure 7h).
On the basis of the results obtained, expressing the distribution of quarries in the province of Settat, it appears that the distribution of quarries significantly differs from one area to another. It is characterized by a high concentration in the circle of Ben Ahmed. The geographical distributions of quarries, as well as production capacity, are affected by two significant factors: • Natural Factors: hydrological (Oued Oum Errabiâ) and/or geological characteristics of the commune (massive rocks, carbonates, clays ... etc.); • Economic and logistical factors: construction of significant projects (dams and highways) or the presence of material-consuming industries (cement factories, Brickworks, and Ceramic Units).
The concentration of quarries in some areas of the Settat province of can have environmental impacts on the air, soil, water resources, fauna, and flora of the territory. In this respect, and to address these kinds of problems, it is recommended to: • Follow up on this study with an environmental assessment study of quarries, particularly on agricultural soils, underground and surface water resources, and air (greenhouse gas emissions and olfactory nuisances); • set priority directions, including: − enhancing the use of materials not derived from quarries; − rationally using materials; − fighting against illegal exploitation; − optimizing the choice of quarry sites, and how they are operated to respect the environment. • track and control quarry operations throughout the quarry lifecycle: from the application for exploitation to its rehabilitation.
It should be noted that as stipulated in the new law no. 27-13, most of these points will be addressed as part of the development of the regional quarries master plan. This scheme is designed to ensure better resources management by defining the general conditions for quarries implantation in the province. As such, it will aid the decisionmaking of the administration when an application for a quarry is presented.

CONCLUSIONS
Through this study, several maps were produced dealing with the spatial distribution of quarries by materials in the territory of the Settat province. This review was able to highlight the key elements behind the development of construction material extractions in the province as well as indicated the most concentrated and productive areas. This study will form the basis of an environmental assessment of quarrying in the province, mainly since most of the quarries were operated under archaic regulations of 1914, modified in 1917 and 1929.