Ayşen Davraz

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.

Evaluation of water quality using water quality index (WQI) method and GIS in Aksu River (SW-Turkey)

The aim of this study is evaluate water quality of the Aksu River, the main river recharging the Karacaören-1 Dam Lake and flowing approximately 145km from Isparta province to Mediterranean. Due to plan for obtaining drinking water from the Karacaören-1 Dam Lake for Antalya Province, this study has great importance. In this study, physical and chemical analyses of water samples taken from 21 locations (in October 2011 and May 2012, two periods) through flow path of the river were investigated. The analysis results were compared with maximum permissible limit values recommended by World Health Organization and Turkish drinking water standards. The water quality for drinking purpose was evaluated using the water quality index (WQI) method. The computed WQI values are between 35.6133 and 337.5198 in the study. The prepared WQI map shows that Karacaören-1 Dam Lake generally has good water quality. However, water quality is poor and very poor in the north and south of the river basin. The effects of punctual and diffuse pollutants dominate the water quality in these regions. Furthermore, the most effective water quality parameters are COD and Mg on the determination of WQI for the present study.

Evaluation of the groundwater quality with WQI (Water Quality Index) and multivariate analysis: a case study of the Tefenni plain (Burdur/Turkey)

Groundwater is a vital source of water for domestic and agricultural activities in the Tefenni plain. Therefore, groundwater quality, seasonal variations and its suitability for drinking, irrigation and industrial usage were evaluated. In this study, 56 water samples were collected from springs, wells, and lake in dry and wet seasons. Ca–Mg–HCO3, Mg–Ca–HCO3, Na–CO3–Cl, and Na–HCO3–Cl water types are the dominant water types in the investigation area. Parameters, which are controlled to chemical variations of groundwater, were analyzed with R-mode factor and correlation analysis. According to R-mode factor analysis, total dissolved solids, Na, Cl, HCO3, and NH3 are the most important parameters. In addition, Water Quality Index (WQI) was applied to suitability for drinking purpose and to investigation of groundwater quality. Quality of groundwaters are suitable for drinkable both dry and wet season in study area. In terms of the irrigation and industrial usage, generally groundwater is suitable in dry season but is not suitable in wet season. Groundwater chemistry is affected with water–rock interaction and densely agricultural activities.

Assessment of geochemistry and hydrogeochemical processes in groundwater of the Tefenni plain (Burdur/Turkey)

The Tefenni (Burdur) plain is located in the southwest of Turkey and is semi-closed basin. Groundwater is densely used as drinking, irrigation and domestic water in the Tefenni plain. Hydrogeochemical processes controlling groundwater chemistry and geochemical assessment of groundwater were investigated in the Tefenni (Burdur/Turkey) plain. The conceptual hydrogeological model of the plain was prepared for qualitative description of the underground geology and interpretation of hydrogeochemical processes of the study area. In this study, groundwater samples for two seasons were analyzed and major ion chemistry of groundwater was researched to understand the groundwater geochemistry. Two major hydrochemical facies (Ca2+–Mg2+–HCO3− and Mg2+–Ca2+–HCO3−) were determined in the area. Mg2+, Na+, SO42− and Cl− concentrations of water samples increased seasonally related to ion exchange of minerals in rocks by rainwater in wet season. Various graphical plots and multivariate statistical analysis (Pearson correlation analysis) were used for identifying the occurrence of different geochemical processes. Carbonate weathering in dry season and silicate weathering in wet season were the major hydrogeochemical processes in the study area. In addition, ion exchange and reverse ion exchange were two possible processes of water–rock interaction in the basin. The mechanism controlling groundwater chemistry at the Tefenni plain is originally regulated by the geogenic process rather than antropogenic activities.

Groundwater quality assessment and its suitability in Çeltikçi plain (Burdur/Turkey)

The Çeltikçi (Burdur) plain is located in the southwest of Turkey and is a semi-closed basin. Groundwater is densely used as drinking, irrigation and domestic water in the plain. Hydrogeochemical processes controlling groundwater chemistry and geochemical assessment of groundwater were investigated in the Çeltikçi (Burdur/Turkey) plain. In this study, groundwater samples for two seasons were analyzed and major ion chemistry of groundwater was researched to understand the groundwater geochemistry. Two major hydrochemical facies (Ca–HCO3 and Ca–Mg–HCO3) were determined in the area. Various graphical plots and multivariate statistical analysis were used for identifying the occurrence of different geochemical processes. In the study area, weathering is one of the key geochemical processes which controlled the solute concentration in groundwater. Chemical indexes such as sodium adsorption ratio, %Na, residual sodium carbonate, magnesium hazard and permeability index were calculated and results show that groundwater is suitable for irrigation purpose except for permeability index values. Concentrations of Mn, NO3 and total hardness exceed the prescribed limits of WHO and are the major limiting parameters of groundwater use for potable and domestic purposes.

Evaluation of potential human health risk and investigation of drinking water quality in Isparta city center (Turkey)

Isparta city center is selected as a work area in this study because the public believes that the tap water is dirty and harmful. In this study, the citys drinking water in the distribution system and other spring waters which are used as drinking water in this region were investigated from the point of water quality and health risk assessment. Water samples were collected from major drinking water springs, tap waters, treatment plants and dam pond in the Isparta province center. Ca-Mg-HCO3, Mg-Ca-HCO3, Ca-Na-HCO3, Ca-HCO3, Ca-HCO3-SO4 and Ca-Mg-HCO3-SO4 are dominant water types. When compared to drinking water guidelines established by World Health Organization and Turkey, much greater attention should be paid to As, Br, Fe, F, NH4, PO4 through varied chemicals above the critical values. The increases of As, Fe, F, NH4 and PO4 are related to water-rock interaction. In tap waters, the increases of As and Fe are due to corrosion of pipes in drinking water distribution systems. The major toxic and carcinogenic chemicals within drinking water are As and Br for both tap water and spring water. Also, F is the non-carcinogenic chemical for only spring waters in the study area.

Hydrogeological investigation of Sarkikaraagac Basin (Isparta, Turkey) and groundwater vulnerability.

The purpose of this study is to investigate the hydrogeology of the Sarkikaraagac Basin in southwest Turkey and to assess its groundwater vulnerability. The groundwater of the basin, used for both drinking and irrigation, is discharged to the Beysehir Lake, the largest in the Lake District. Groundwaters have Ca-Mg-HCO3 and Mg-HCO3 facies. The most important pollutant factor is anthropogenic pollution, originating from dense and widespread agricultural activity, which moves through the groundwater to the Beysehir Lake. The groundwater vulnerability of the alluvial aquifer is determined with different parameters using the DRASTIC approach. The most vulnerable area, covering 30.23% of the basin, is strongly correlated with known pollution values.

Assessment of groundwater quality and health risk in drinking water basin using GIS

Eğirdir Lake basin was selected as the study area because the lake is the second largest freshwater lake in Turkey and groundwater in the basin is used as drinking water. In the present study, 29 groundwater samples were collected and analyzed for physico-chemical parameters to determine the hydrochemical characteristics, groundwater quality, and human health risk in the study area. The dominant ions are Ca2+, Mg2+, HCO32-, and SO42. According to Gibbs plot, the predominant samples fall in the rock-water interaction field. A groundwater quality index (WQI) reveals that the majority of the samples falls under good to excellent category of water, suggesting that the groundwater is suitable for drinking and other domestic uses. The Ca-Mg-HCO3, Ca-HCO3, Ca-SO4-HCO3, and Ca-Mg-HCO3-SO4 water types are the dominant water types depending on the water-rock interaction in the investigation area. Risk of metals to human health was then evaluated using hazard quotients (HQ) by ingestion and dermal pathways for adults and children. It was indicated that As with HQ ingestion >1 was the most important pollutant leading to non-carcinogenic concerns. It can be concluded that the highest contributors to chronic risks were As and Cr for both adults and children.

Groundwater balance estimation and sustainability in the Sandıklı Basin (Afyonkarahisar/Turkey)

The Sandıklı (Afyonkarahisar) Basin is located in the southwest of Turkey and is a semi-closed basin. Groundwater is widely used for drinking, domestic and irrigation purposes in the basin. The mismanagement of groundwater resources in the basin causes negative effects including depletion of the aquifer storage and groundwater level decline. To assure sustainability of the basin, determination of groundwater budget is necessary. In this study, the water-table fluctuation (WTF) and the meteorological water budget (MWB) methods were used to estimate groundwater budget in the Sandıklı basin (Turkey). Conceptual hydrogeological model of the basin was used for understanding the relation between budget parameters. The groundwater potential of the basin calculated with MWB method as 42.10 × 106 m3/year. In addition, it is also calculated with simplified WTF method as 38.48 × 106 m3/year.

Assessment of trace metal contents in water and bottom sediments from Eğirdir Lake, Turkey

The concentration of metals (Pb, As, Co, Cu, Ni, Zn, Fe and Mn) was investigated in water and sediment samples of Eğirdir Lake. The Lake is the second largest fresh water lake of Turkey and it is used as drinking water in the region. The anthropogenic pollutants are primary sources of trace metals which are negatively affected lake water quality. These negative effects were observed in both lake water and bottom sediments. According to obtained data, Pb, Cu, Ni, Fe and Zn have significant enrichment in sediments samples. In addition, the hydrodynamic model of the lake was determined as effectively for Pb, Co, Cu, Ni, Zn, Fe and Mn accumulations. Also, the effect of anthropogenic pollutants was found to be more dominant than geogenic effect in metal accumulation of the lake bottom sediments. Therefore, anthropogenic pollutants within the lake basin should be consistently controlled for the sustainable usage of the lake.