Erhan Sener

Combining AHP with GIS for landfill site selection: a case study in the Lake Beyşehir catchment area (Konya, Turkey).

Landfills are the most common method for the disposal of municipal solid waste (MSW) in Turkey. However, determining the location of landfill sites is a difficult and complex process because it must combine social, environmental and technical parameters. Additionally, it depends on several criteria and regulations. The main objective of this study was to select of a landfill site for the Lake Beyşehir catchment area. The Beyşehir Lake is the largest freshwater lake and drinking water reservoir in Turkey, but there is no controlled landfill site in the region. Therefore, the landfill site should be determined such that the lake is protected. To determine the most suitable landfill site, an analytical hierarchy process (AHP) was combined with a geographic information system (GIS) to examine several criteria, such as geology/hydrogeology, land use, slope, height, aspect and distance from settlements, surface waters, roads, and protected areas (ecologic, scientific or historic). Each criterion was evaluated with the aid of AHP and mapped by GIS. Data were assorted into four suitability classes within the study area, i.e., high, moderate, low and very low suitability areas, which represented 3.24%, 7.55%, 12.70% and 2.81%, of the study area, respectively. Additionally, 73.70% was determined to be completely unsuitable for a landfill site. As a result, two candidate landfill sites are suggested and discussed. The final decision for landfill site selection will require more detailed field studies.

Solid waste disposal site selection with GIS and AHP methodology: a case study in Senirkent–Uluborlu (Isparta) Basin, Turkey

The appropriate site selection for waste disposal is one of the major problems in waste management. Also, many environmental, economical, and political considerations must be adhered to. In this study, landfill site selection is performed using the Geographic Information System (GIS), the Analytical Hierarchy Process (AHP), and the remote sensing methods for the Senirkent–Uluborlu Basin. The basin is located in the Eğirdir Lake catchment area, which is one of the most important fresh water in Turkey. So, waste management must be regulated in the basin. For this aim, ten different criteria (lithology, surface water, aquifer, groundwater depth, land use, lineaments, aspect, elevation, slope, and distance to roads) are examined in relation to landfill site selection. Each criterion was identified and weighted using AHP. Then, each criterion is mapped using the GIS technique, and a suitability map is prepared by overlay analyses. The results indicate that 96.3% of the area in the basin is unsuitable; 1.6%, moderately suitable; and 2.1%, most suitable. Finally, suitable regions in the basin are determined for solid waste landfill disposal and checked in the field. The selected and investigated regions are considered to be suitable for the landfill.

Assessment of groundwater vulnerability based on a modified DRASTIC model, GIS and an analytic hierarchy process (AHP) method: the case of Egirdir Lake basin (Isparta, Turkey)

A DRASTIC-model method based on a geographic information system (GIS) was used to study groundwater vulnerability in Egirdir Lake basin (Isparta, Turkey), an alluvial area that has suffered agricultural pollution. ‘Lineament’ and ‘land use’ were added to the DRASTIC parameters, and an analytic hierarchy process (AHP) method determined the rating coefficients of each parameter. The effect of lineament and land-use parameters on the resulting vulnerability maps was determined with a single-parameter sensitivity analysis. Of the DRASTIC parameters, land use affects the aquifer vulnerability map most and lineament affects it least, after topography. A simple linear regression analysis assessed the statistical relation between groundwater nitrate concentration and the aquifer vulnerability areas; the highest R2 value was obtained with the modified-DRASTIC-AHP method. The DRASTIC vulnerability map shows that only the shoreline of Egirdir Lake and the alluvium units have high contamination potential. In this respect, the modified DRASTIC vulnerability map is quite similar. According to the modified-DRASTIC-AHP method, the lakeshore areas of Senirkent-Uluborlu and Hoyran plains, and all of the Yalvaç-Gelendost plain, have high contamination potential. Analyses confirm that groundwater nitrate content is high in these areas. By comparison, the modified-DRASTIC-AHP method has provided more valid results.RésuméUne méthode basée sur un modèle DRASTIC modifié et sur un SIG a été utilisée pour étudier la vulnérabilité de la nappe du bassin du Lac Egirdir (Isparta, Turquie), une zone alluviale qui a souffert d’une pollution agricole. ‘Lineament’ et ‘land use’ ont été superposés aux paramètres DRASTIC, et une méthode analytique basée sur une démarche hiérarchisée (AHP) a déterminé la pondération de chaque paramètre. L’incidence des paramètres ‘linéament’ et ‘land-use’ sur les cartes de vulnérabilité a été déterminée par analyse de sensibilité mono-paramétrique. Parmi les paramètres DRASTIC, les composantes ‘land use’ affectent le plus la carte de vulnérabilité de l’aquifère et ‘linéament’ de façon moindre après la topographie. Une analyse de régression linéaire simple a établi la relation statistique entre la concentration en nitrates de l’eau du sol et la vulnérabilité spécifique de la zone ; la plus grande valeur R2 a été obtenue avec la méthode DRASTIC-AHP modifiée. La carte de vulnérabilité DRASTIC montre que la seule ligne de rivage du Lac Elgidir et les unités alluvionnaires ont un potentiel de contamination élevé. Sous cet angle, la carte de vulnérabilité DRASTIC modifiée est tout à fait similaire. Selon la méthode DRASTIC-AHP modifiée, les régions rivulaires des plaines Senirkent-Uluborlu et Hoyran, et la totalité de la plaine Yalvaç-Gelendost ont un potentiel de contamination élevé. Des analyses confirment que la concentration en nitrate dans la nappe est élevée dans ces régions. Comparativement, la méthode DRASTIC-AHP modifiée a fourni de meilleurs résultats.ResumenSe usó un método del modelo DRASTIC basado en un sistema de información geográfica (SIG) para estudiar la vulnerabilidad del agua subterránea en la Cuenca del lago Egirdir (Isparta, Turquía), un área aluvial que ha sufrido contaminación agrícola. Se adicionaron ‘Lineamentos’ y ‘uso de la tierra’ a los parámetros de DRASTIC, y un método del proceso jerárquico analítico (AHP) determinó los coeficientes de calificación de cada uno de los parámetros. El efecto de los parámetros de lineamientos y uso de la tierra sobre los mapas de vulnerabilidad resultantes se determinó con un simple análisis de sensibilidad de los parámetros. De los parámetros de DRASTIC, el uso de la tierra es el que afecta más la vulnerabilidad del acuífero y los lineamientos en menor grado, después de la topografía. Un análisis de regresión lineal simple evaluó la relación estadística entre la concentración de nitrato en el agua subterránea y las áreas de vulnerabilidad del acuífero: el valor más alto de R2 se obtuvo con el método DRASTIC-AHP modificado. El mapa de vulnerabilidad DRASTIC muestra que solamente la costa del Lago Egirdir y las unidades aluviales tienen una alta contaminación potencial. En ese sentido el mapa de vulnerabilidad DRASTIC modificado es bastante similar. De acuerdo al método DRASTIC-AHP modificado, las áreas costeras del lago de las planicies de las áreas de Senirkent-Uluborlu y Hoyran, y toda la planicie de Yalvaç-Gelendost, tienen un alto potencial a la contaminación. Los análisis confirman que el contenido de nitrato en el agua subterránea es alto es estas áreas. Por comparación, el método DRASTIC-AHP modificado ha provisto resultados más validos.摘要用基于地理信息系统(GIS)的DRASTIC模型方法来研究Egirdir湖盆(伊斯帕尔塔,土耳其)的地下水脆弱性,这个湖盆是个冲积区并且遭受了农业污染。“线性构造”和“土地利用”被增加为DRASTIC模型的参数,用层次分析法来确定每个参数的等级系数。线性构造和土地利用两个参数对脆弱性分布图的影响是由单一参数敏感性分析方法来确定的。在DRASTIC模型的所有参数中,土地利用对含水层脆弱性分布图的影响最大,线性构造影响最小,并且排在地形参数之后。用一个简单的线性回归分析评估了地下水硝酸盐含量和含水层脆弱性面积之间的统计关系,用改进的DRASTIC-AHP方法获得的相关性系数最大。DRASTIC脆弱性分布图表明只有Egirdir湖的湖岸线和冲积层单元遭受污染的可能性比较大。从这一点上来看,改进的DRASTIC脆弱性分布图与之非常的相似。根据改进的DRASTIC-AHP方法分析得出,Senirkent-Uluborlu 和 Hoyran 平原的湖岸区域以及整个Yalvaç-Gelendost 平原遭受污染的可能性都比较大。分析也证实了这些区域的硝酸盐含量比较高。通过比较,改进的DRASTIC-AHP方法提供了更有效的结果。ResumoFoi usado um método do modelo DRASTIC baseado num sistema de informação geográfica (SIG) para estudar a vulnerabilidade da água subterrânea na bacia do Lago Egirdir (Isparta, Turquia), uma área aluvionar afetada por poluição agrícola. ‘Lineamentos’ e ‘Uso do solo’ foram adicionados aos parâmetros DRASTIC e um método de processo analítico hierárquico (PAH) permitiu calcular os coeficientes de valoração de cada parâmetro. O efeito dos parâmetros de lineamento e de uso do solo nos mapas de vulnerabilidade gerados foi determinado com uma análise de sensibilidade de cada parâmetro. Do conjunto dos parâmetros DRASTIC, o uso do solo é o que afeta mais o mapa de vulnerabilidade do aquífero e o de lineamentos o que afeta menos, depois da topografia. Uma simples análise de regressão linear permitiu avaliar a relação estatística entre a concentração de nitrato na água subterrânea e as áreas de vulnerabilidade do aquífero; o valor mais elevado de R2 foi obtido com o método DRASTIC-PAH modificado. O mapa de vulnerabilidade DRASTIC mostra que somente a margem do Lago Egirdir e as unidades aluvionares têm elevado potencial de contaminação. Neste aspecto, o mapa de vulnerabilidade DRASTIC modificada é bastante similar. De acordo com o método DRASTIC-PAH modificado, as margens do lago nas planícies de Senirkent-Uluborlu e Hoyran, e toda a planície de Yalvaç-Gelendost, têm elevado potencial de contaminação. As análises confirmam que nestas áreas a concentração de nitrato na água subterrânea é elevada. Por comparação, o método DRASTIC-PAH modificado proporcionou resultados mais válidos.ÖZETEğirdir Gölü havzası içerisindeki tarımsal kirleticilerden etkilenen alüvyon alanların yeraltısuyu kirlenebilirliklerinin belirlenmesinde CBS tabanlı DRASTIC metot kullanılmıştır. Ayrıca, DRASTIC parametrelerine “Çizgisellik” ve “arazi kullanım” parametreleri eklenmiş ve her bir parametrenin reyting katsayıları Analitik Hiyerarşi Süreci (AHS) metodu ile belirlenmiştir. Çizgisellik ve arazi kullanım parametrelerinin çalışma sonucunda elde edilen kirlenebilirlik haritası üzerindeki etkileri ise Tek Parametreli Hassasiyet Analizi ile belirlenmiş ve DRASTIC parametrelerinden arazi kullanım parametresinin akifer kirlenebilirlik haritasını en fazla etkilediği, çizgisellik parametresinin etkisinin ise topoğrafya parametresinden sonra en az olduğu görülmüştür. Basit lineer regresyon analizi ile yeraltısuyu nitrat konsantrasyonları ve akifer kirlenebilirlik haritaları arasındaki istatistiksel ilişki değerlendirildiğinde ise en yüksek R2 değerinin Modifiye-DRASTIC-AHS metodu ile hazırlanan kirlenebilirlik haritasına ait olduğu belirlenmiştir. Çalışmada DRASTIC kirlenebilirlik haritası ile Modifiye-DRASTIC kirlenebilirlik haritasının oldukça benzer sonuçlara sahip olduğu ve bu haritalara göre yalnızca Eğirdir Gölü kıyılarının ve alüvyon birimlerin yüzeylendiği alanların yüksek kirlenebilirlik potansiyeline sahip olduğu gözlenmektedir. Modifiye-DRASTIC-AHS metoduna göre ise, Senirkent-Uluborlu ve Hoyran ovalarının göl kıyı alanları ve Yalvaç-Gelendost ovasının tamamı yüksek kirlenebilirlik potansiyeline sahiptir ve bu sonuçlar sözkonusu alanlarda yeraltısuyunda ölçülen yüksek nitrat konsantrasyonları ile doğrulanmaktadır. Çalışmada kullanılan üç farklı yöntem karşılaştırıldığında, Modifiye DRASTIC-AHS metodunun diğerlerine göre daha gerçekçi sonuçlar verdiği belirlenmiştir.

Determination of canal orifice co-ordinates and MB2 incidence of maxillary first molars in a Turkish sub-population

Abstract Objectives. To measure the co-ordinates of the root canal orifices and to determine the incidence of mesiobuccal-2 (MB2) in maxillary first molars in a Turkish sub-population. Materials and methods. Standard digital photographs were taken under a stereomicroscope from the occlusal aspect of each tooth (n = 176) before and after crown removal. Canal orifices were negotiated under moderate magnification using dental loupes. The coordinates of the orifices and the distances of each from the central fossa were measured by using geographic software. Intensity maps of the orifice locations were created by using the co-ordinates of all canal orifices. A representative map was drawn using the mean values of orifice locations and access projection area. Results. In the right maxillary first molars, the mean values for the (X, Y) co-ordinates were (0.67, 2.68) for mesiobuccal-1 (MB1), (0.81, 0.84) for MB2, (−1.12, 1.26) for distobuccal-1 (D1), (−0.89, 0.23) for distobuccal-2 (D2) and (0, −2.50) for palatinal (P); the corresponding mean values in the left maxillary first molars were (−0.78, 2.56), (−0.98, 0.90), (0.99, 1.18), (0.69, 0.78) and (0.00, −2.53), respectively. The average MB1–MB2 distance was 1.97 mm. Distobuccalcanal orifices were localized at the distal side of the center in 98.3% of teeth. The incidence of MB2 was 46.02%. Conclusions. The distobuccal canal orifice is mostly located on the distal side of the central fossa. Thus, it should be considered that the access cavity of the maxillary molars may not be always limited mesially. The incidence of MB2 in this sub-population was 46.02%, which is of great importance clinically.