Comparison of the AVI, modified SINTACS and GALDIT vulnerability methods under future climate-change scenarios for a shallow low-lying coastal aquifer in southern Finland

Peer reviewe

Évaluation de la vulnérabilité à la pollution potentielle de la nappe côtière alluvionnaire de Meltine-Ras Jebel-Raf Raf (Nord-Est tunisien) selon les méthodes paramétriques DRASTIC, SINTACS et SI

La nappe alluvionnaire de Metline-Ras Jebel-Raf Raf (gouvernorat de Bizerte, côte Nord Est de la Tunisie), qui occupe une superficie de 35 km2, représente une ressource économique jugée prioritaire du fait qu’elle est utilisée dans les domaines d’irrigation et de consommation domestique. L’aire de la nappe est occupée essentiellement par des zones agricoles caractérisées par une utilisation de plus en plus importante des engrais chimiques qui représentent, en plus des rejets des zones industrielles, un risque permanent pour la qualité des eaux souterraines. L’étude de la vulnérabilité à la pollution par les polluants inorganiques de cette nappe a été effectuée en appliquant les méthodes DRASTIC standard (Aller et al., 1987; Engel et al., 1996), SINTACS (Civita, 1994) et SI (Ribeiro, 2000), avec l’aide des logiciels des systèmes d’information géographique, ARC/Info et Idrisi. Une comparaison statistique des cartes de vulnérabilité obtenues a été effectuée. Cette comparaison a montré une certaine ressemblance entre les résultats obtenus en utilisant les méthodes SINTACS et SI. En revanche, la carte DRASTIC standard s’avère différente par rapport aux autres.The alluvial aquifer of Metline-Ras Jebel-Raf Raf (prefecture of Bizerta, northeast coast of Tunisia), which occupies a surface of 35 km2, is of great economic importance because it is used for irrigation and domestic consumption. The area of the aquifer is essentially occupied by agricultural zones characterised by an increasing use of chemical fertilizers. These chemical fertilizers, together with discharges from the industrial zones that have appeared during the last 25 years, threaten the quality of the ground waters. The vulnerability of the aquifer to pollution by generic pollutants has been studied by applying the following methods: the generic DRASTIC method, the SINTACS method and the SI method. For the application of these methods GIS techniques were used. A statistical comparison among the vulnerability maps generated by each method has been carried out. On the one hand, this comparison shows a certain similarity between the results obtained using the SI and SINTACS methods. On the other hand, the DRASTIC map classification shows different results

Vulnerability Mapping of an Apulian Deep Carbonate Aquifer Using GIS

Computer techniques such as Geographic Information Systems are applied to the evaluation of the vulnerability of a deep carbonate aquifer. The study area, of about 150 km2, is located in the low Murgia Plateau (Apulia) and characterized by Mesozoic limestone and dolomite rocks of several thousand meters thickness. A wide and thick aquifer resides in these carbonate rocks. Its groundwater flows toward the sea mainly under pressure and with maximum piezometric level of about 200 m a.s.l.. Due to their high quality, the water resources of this aquifer are particularly valuable for the local communities and therefore must be protected from pollution and inappropriate use. The vulnerability map of the aquifer is an indispensable tool for the effective management of groundwater resources and to support environmental planning. Several approaches have been proposed by different authors to evaluate intrinsic vulnerability. Most of the methods for detailed vulnerability mapping are based on the integrated analysis of several variables using different algorithms. Geographic Information Systems are advanced computer tools for the analysis of georeferenced data in 2D and 3D and can be effectively applied to the implementation of evaluation models. In this study the SINTACS evaluation method was implemented in a GIS and a digital vulnerability map produced. The different data taken into consideration in this analysis, such as depth to water, actual infiltration, pollution attenuation capacity of unsaturated zone, land cover, hydrogeological features of saturated aquifer, hydraulic conductivity, terrain slope, geology and geological structures, were georeferenced and converted into digital form. Each variable corresponds to a separate data layer made of graphic and attribute data. The computerized multilayer analysis performed by the GIS is time effective and leads to more comprehensive and accurate results with better spatial resolution

Intrinsic vulnerability assessment of the south-eastern Murge (Apulia, southern Italy)

Maps of areas with different vulnerability degrees are an integral part of environmental protection and management policies. It is difficult to assess the intrinsic vulnerability of karst areas since the stage and type of karst structure development and its related underground discharge behaviour are not easy to determine. Therefore, some improvements, which take into account dolines, caves and superficial lineament arrangement, have been integrated into the SINTACS R5 method and applied to a karst area of the south-eastern Murge (Apulia, southern Italy). The proposed approach integrates the SINTACS model giving more weight to morphological and structural data; in particular the following parameters have been modified: depth to groundwater, effective infiltration action, unsaturated zone attenuation capacity and soil/overburden attenuation capacity. Effective hydrogeological and impacting situations are also arranged using superficial lineaments and karst density. In order to verify the reliability of the modified procedure, a comparison is made with the original SINTACS R5 index evaluated in the same area. The results of both SINTACS index maps are compared with karst and structural features identified in the area and with groundwater nitrate concentrations recorded in wells. The best fitting SINTACS map is then overlaid by the layout of potential pollution centres providing a complete map of the pollution risk in the area

MULTI-SCALE ASSESSMENT OF GROUNDWATER VULNERABILITY TO POLLUTION: STUDY CASES FROM CAMPANIA REGION (SOUTHERN ITALY)

In the Campania region (southern Italy), assessment of groundwater vulnerability is an important factor to be tackled for a proper management of risk to aquifer pollution, which is fostered by both high dependence of aqueduct systems on groundwater resources and the widespread agricultural and urbanized land uses of the territory. The different physiographic, geological and hydrogeological conditions of the region, coupled with high anthropic pressure, make such assessment complex to be dealt with, but at the same time mandatory to be accomplished. The proposed study has been developed into the framework of the “Campania Trasparente” project, which has been funded by the regional government to assess environmental factors controlling the quality of agricultural and livestock food productions. Specifically, it belongs to the research topic regarding the assessment of groundwater quality, with a special focus on the assessment of groundwater vulnerability. In this research a multi-scale approach for the assessment of groundwater vulnerability is carried out in order to propose suitable methods depending on extension of territory to be studied and related types and spatial density of available data. Scales considered were a) regional, including the whole Campania region; b) intermediate, identified with that of a single representative aquifer; c) site-specific, or local, related to a portion of aquifer for which a high spatial density of data is available.The applied methods were chosen among the many known in literature and adapted to the specific study cases. At the regional scale, the parametric SINTACS method (CIVITA & DE MAIO, 2000) has been applied to the whole region and adapted to types and spatial density of available data. At the intermediate scale, or aquifer scale, the Mt. Terminio karst aquifer was chosen as representative for the application of different parametric methods, also specifically designed for karst aquifers. At the site-specific scale, a representative sector of a shallow alluvial aquifer, located in the adjoining Casalnuovo di Napoli-Volla municipalities, in the Campania plain, at the eastern border of the city of Naples, has been studied by numerical modeling for the estimation of travel time of nitrate pollutant through the vadose zone. The obtained results can be conceived as useful for supporting a proper territorial planning aimed at the management of risk to pollution of groundwater resources