Groundwater risk intensity mapping in semi-arid regions using optical remote sensing data as an additional tool

Due to semi-arid to arid climatic conditions, Jordan has limited groundwater resources. As a result of agricultural activities and untreated wastewater, most of the groundwater in the karstic areas is microbiologically contaminated. Groundwater vulnerability, hazards, and risk intensity were mapped (scale 1:50,000) at a test site near the Jordan Rift Valley. The mapping included the use of optical remote sensing to complement conventional data in areas with poor data. LANDSAT ETM+ data, and colour and panchromatic aerial photographs at different scales were incorporated using visual image interpretation and digital image processing. The applicability of the different remote sensing data sources is discussed and recommendations for their usage are given. Information derived from digital images offers new opportunities for vulnerability and hazard assessment, particularly when related to land use, vegetation cover, urbanisation and infrastructure. The resulting maps indicate clearly the vulnerable areas and the “hot spots” of potential contamination in the test site and form an important basis for integrated groundwater management studies and the long-term planning of protective measures. The application and transferability of the European vulnerability approach (COST Action 620) to the test site in Jordan proved to be good, in general, although modifications were necessary to suit local conditions.

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Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorised users.

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Résumé La Jordanie ne dispose que de ressources limitées en eaux souterraines, étant donné le climat semi-aride à aride prévalant dans ce pays. La contamination microbiologique de la plupart des eaux souterraines des régions karstiques est due aux activités agricoles et l’absence de traitement des eaux usées. La vulnérabilité des eaux souterraines, et le danger et l’intensité du risque de leur contamination ont été cartographiés (à l’échelle de 1:50 000) pour un site d’étude situé près de la vallée du Rift du Jourdain. La cartographie inclut l’utilisation de données optiques de télédétection pour complémenter les sources de données conventionnelles, dans les zones où la couverture est déficiente. Des données de LANDSAT ETM+ et des photographies aériennes en couleur et panchromatiques à différentes échelles ont été incorporées en utilisant des méthodes d’interprétation visuelle et informatique de l’image. La qualité des différentes sources de données de télédétection est discutée et évaluée, et des recommandations pour leur utilisation sont suggérées. L’informations obtenue des images digitales offre de nouvelles opportunités pour l’évaluation des vulnérabilités et des dangers, surtout reliés à l’usage du sol, la couverture végétale, l’urbanisation et les diverses infrastructures. Les cartes ainsi obtenues indiquent clairement les zones vulnérables et les points critiques potentiels pour la contamination du site d’étude et forment une base importante pour l’étude de la gestion intégrée des eaux souterraines et pour la planification à long terme des mesures de protection. L’applicabilité de l’approche européenne de cartographie de la vulnérabilité et des risques (COST action 620) au site d’étude jordanien est généralement approprié, même si certaines modifications ont été nécessaires pour s’ajuster aux particularités régionales.

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Resumen Los recursos hídricos subterráneos en Jordania son limitados debido principalmente a su clima semi árido. En la mayoría de las áreas kársticas, las aguas subterráneas están contaminadas microbiológicamente a consecuencia de la actividad agrícola y de las aguas residuales. Por ello, se han realizado mapas de peligro, vulnerabilidad e intensidad del riesgo (a escala 1/50.000) de un área piloto próxima al Rift en Jordania. Los mapas han sido elaborados con el apoyo de técnicas de teledetección en aquellas zonas donde la información era escasa. Se han utilizado imágenes del LANDSAT ETM+ a y fotografía aérea, de color y pancromática, a diferentes escalas para el procesamiento de las imágenes digitales y la fotointerpretación. En este trabajo se discute y se dan recomendaciones sobre la aplicabilidad de las diferentes imágenes de satélite en los análisis de teledetección. Los datos que se pueden derivar de las imágenes digitales son un avance para la evaluación de la vulnerabilidad y los peligros de contaminación, particularmente aquellos referidos a usos del suelos, cubierta vegetal e infraestructuras urbanas. Los mapas resultantes muestran claramente la vulnerabilidad y los peligros potenciales de contaminación en la zona de estudio, lo que genera una importante base para los estudios de gestión integrada de las aguas subterráneas y de planificación de las medidas protectoras. La aplicabilidad de la aproximación europea a los estudios de vulnerabilidad en karst (COST Action 620) en la zona de estudio (Jordania) es buena, aunque fueron necesarias algunas leves modificaciones de la metodología para ajustarla a las condiciones locales.

     

Validation of vulnerability mapping methods by field investigations and numerical modelling

Vulnerability maps illustrate the potential threat of contaminants to groundwater and can be considered as important tools for land-use planning and related legislation. For karst areas with characteristic preferential infiltration conditions, vulnerability maps are also excellent tools for source and resource protection. However, the resulting qualitative maps are often inconsistent and even contradictive and thus might lead to inconclusive vulnerability assessments. The results of a validation of vulnerability maps produced using four different methods, DRASTIC, GLA, PI and EPIK, are reported for a karst area in southwest Germany. By means of measured hydraulic and transport parameters of the geological sequence, numerical simulations were used based on a conceptual model for the area under study. The mean transit time through the unsaturated zone (resource protection) was used as the validation parameter. The study demonstrates that the highest level of accuracy is achieved with the GLA- and PI methods. Both DRASTIC and EPIK are not able to incorporate highly variable distributions and thickness of cover sediments and their protective properties in the respective mapping procedure. Thus, vulnerability maps produced with DRASTIC, EPIK, and related methods should be used with care when employed in vulnerability assessments for land use planning and related decision-making.

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Résumé  Les cartes de vulnérabilité illustrent la menace potentielle des contaminants envers les eaux souterraines, et peuvent être considérées comme des outils importants en matière d'aménagement foncier et de réglementation associée. Sur les domaines karstiques, caractérisés par des conditions d'infiltration préférentielle, ces cartes sont également d'excellents outils de protection des sources et des ressources. Cependant, les cartes qualitatives résultantes sont généralement incohérentes voire contradictoires, et peuvent par là-même mener à des évaluations de vulnérabilité peu concluantes. La présente étude expose les résultats de validation de cartes de vulnérabilité produites selon quatre méthodes différentes (DRASTIC, GLA, PI et EPIK), dans le cas d'un domaine karstique du sud-est de l'Allemagne. Par le biais des paramètres de transport et hydrauliques mesurés sur la séquence géologique, des simulations numériques basées sur un modèle conceptuel du secteur d'étude ont été utilisées. Les temps de transit moyens à travers la zone non saturée (protection de la ressource) ont été utilisés comme paramètres de validation. L'étude démontre que le niveau maximum de précision est obtenu par les méthodes GLA et PI. Dans la phase de cartographie, les méthodes EPIK et DRASTIC sont incapables d'intégrer une forte variabilité dans les distributions et les épaisseurs de sédiments de couverture, ainsi que dans leurs potentiels de protection. Aussi, les cartes de vulnérabilité produites par les méthodes DRASTIC et EPIK doivent être utilisées avec précaution dans le cadre des évaluations de vulnérabilité à but décisionnaire pour les aménagements fonciers.

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Resumen  Los mapas de vulnerabilidad ilustran la amenaza potencial de contaminantes para el agua subterránea y pueden ser considerados herramientas importantes para planeamiento del uso de la tierra y legislación relacionada. Para áreas cársticas con sus características condiciones de infiltración preferencial, los mapas de vulnerabilidad son también excelentes herramientas para protección de fuentes y recursos. Sin embargo, los mapas cualitativos resultantes son frecuentemente inconsistentes y hasta contradictorios y por lo tanto podrían conducir a evaluaciones de vulnerabilidad no concluyentes. Los resultados de una validación de mapas de vulnerabilidad producidos usando cuatro métodos diferentes, DRASTIC, GLA, PI y EPIK, son presentados aquí para un área cárstica en Alemania suroccidental. Se usaron simulaciones numéricas usando parámetros hidráulicos y de transporte medidos de la secuencia geológica y basándose en un modelo conceptual del área en estudio. El tiempo promedio de tránsito a través de la zona no saturada (protección del recurso) fue utilizado como el parámetro de validación. El estudio demuestra que el máximo nivel de precisión es alcanzado con los métodos GLA y PI. DRASTIC y EPIK no fueron capaces de incorporar distribuciones altamente variables ni espesor de sedimentos de cubierta y sus propiedades protectivas en el respectivo procedimiento de elaboración de mapas. Por lo tanto los mapas de vulnerabilidad producidos con DRASTIC, EPIK y métodos relacionados deberían ser usados con cuidado cuando se usen en evaluaciones de vulnerabilidad para planeamiento del uso de tierra y toma de decisiones relacionadas.

     

Groundwater sensitivity mapping in Kentucky using GIS and digitally vectorized geologic quadrangles

Groundwater sensitivity (Ray and O’dell in Environ Geol 22:345–352, 1993a) refers to the inherent ease with which groundwater can be contaminated based on hydrogeologic characteristics. We have developed digital methods for identifying areas of varying groundwater sensitivity for a ten county area of south central Kentucky at a scale of 1:100,000. The study area includes extensive limestone karst sinkhole plains, with groundwater extremely sensitive to contamination. Digitally vectorized geologic quadrangles (DVGQs) were combined with elevation data to identify both hydrogeologic groundwater sensitivity regions and zones of “high risk runoff” where contaminants could be transported in runoff from less sensitive to higher sensitivity (particularly karst) areas. While future work will fine-tune these maps with additional layers of data (soils for example) as digital data have become available, using DVGQs allows a relatively rapid assessment of groundwater sensitivity for Kentucky at a more useful scale than previously available assessment methods, such as DRASTIC and DIVERSITY. Geographic definitions: United States of America, Kentucky, Barren River Area Development District.     

Drought risk assessment using remote sensing and GIS techniques

Beginning with a discussion of drought definitions, this review paper attempts to provide a review of fundamental concepts of drought, classification of droughts, drought indices, and the role of remote sensing and geographic information systems for drought evaluation. Owing to the rise in water demand and looming climate change, recent years have witnessed much focus on global drought scenarios. As a natural hazard, drought is best characterized by multiple climatological and hydrological parameters. An understanding of the relationships between these two sets of parameters is necessary to develop measures for mitigating the impacts of droughts. Droughts are recognized as an environmental disaster and have attracted the attention of environmentalists, ecologists, hydrologists, meteorologists, geologists, and agricultural scientists. Temperatures; high winds; low relative humidity; and timing and characteristics of rains, including distribution of rainy days during crop growing seasons, intensity, and duration of rain, and onset and termination, play a significant role in the occurrence of droughts. In contrast to aridity, which is a permanent feature of climate and is restricted to low rainfall areas, a drought is a temporary aberration. Often, there is confusion between a heat wave and a drought, and the distinction is emphasized between heat wave and drought, noting that a typical time scale associated with a heat wave is on the order of a week, while a drought may persist for months or even years. The combination of a heat wave and a drought has dire socio-economic consequences. Drought risk is a product of a region’s exposure to the natural hazard and its vulnerability to extended periods of water shortage. If nations and regions are to make progress in reducing the serious consequences of drought, they must improve their understanding of the hazard and the factors that influence vulnerability. It is critical for drought-prone regions to better understand their drought climatology (i.e., the probability of drought at different levels of intensity and duration) and establish comprehensive and integrated drought information system that incorporates climate, soil, and water supply factors such as precipitation, temperature, soil moisture, snow pack, reservoir and lake levels, ground water levels, and stream flow. All drought-prone nations should develop national drought policies and preparedness plans that place emphasis on risk management rather than following the traditional approach of crisis management, where the emphasis is on reactive, emergency response measures. Crisis management decreases self-reliance and increases dependence on government and donors.     

Water vulnerability assessment in karst environments: a new method of defining protection areas using a multi-attribute approach and GIS tools (EPIK method)

 Groundwater resources from karst aquifers play a major role in the water supply in karst areas in the world, such as in Switzerland. Defining groundwater protection zones in karst environment is frequently not founded on a solid hydrogeological basis. Protection zones are often inadequate and as a result they may be ineffective. In order to improve this situation, the Federal Office for Environment, Forests and Landscape with the Swiss National Hydrological and Geological Survey contracted the Centre of Hydrogeology of the Neuchatel University to develop a new groundwater protection-zones strategy in karst environment. This approach is based on the vulnerability mapping of the catchment areas of water supplies provided by springs or boreholes. Vulnerability is here defined as the intrinsic geological and hydrogeological characteristics which determine the sensitivity of groundwater to contamination by human activities. The EPIK method is a multi-attribute method for vulnerability mapping which takes into consideration the specific hydrogeological behaviour of karst aquifers. EPIK is based on a conceptual model of karst hydrological systems, which suggests considering four karst aquifer attributes: (1) Epikarst, (2) Protective cover, (3) Infiltration conditions and (4) Karst network development. Each of these four attributes is subdivided into classes which are mapped over the whole water catchment. The attributes and their classes are then weighted. Attribute maps are overlain in order to obtain a final vulnerability map. From the vulnerability map, the groundwater protection zones are defined precisely. This method was applied at several sites in Switzerland where agriculture contamination problems have frequently occurred. These applications resulted in recommend new boundaries for the karst water supplies protection-zones. Received: 27 October 1997 · Accepted: 4 July 1998     

Groundwater withdrawal impacts in a karst area

During a 3000-gpm pump test on a groundwater supply well in Augusta County, Virginia, residential properties were impacted. The impacts included lowered farm pond water levels, development of a sinkhole, and water level decrease in residential wells. A study was performed to assess whether a lower design yield was possible with minimal impacts on adjacent property. This study included a 48-h 1500-gpm pump test that evaluated impacts due to: (1) sinkhole development and potential damage to homes, (2) loss of water in residential wells, and (3) water-quality degradation. Spring flows, residential well levels, survey monuments, and water quality were monitored. Groundwater and surface water testing included inorganic water-quality parameters and microbiological parameters. The latter included particulate analyses,Giardia cysts, and coliforms, which were used to evaluate the connection between groundwater and local surface waterbodies. Although results of the study indicated a low potential for structural damage due to future sinkhole activity, it showed that the water quality of some residential wells might be degraded. Because particulate analyses confirmed that groundwater into the supply well is under the direct influence of surface water, it was recommended that certain residents be placed on an alternate water supply prior to production pumping and that filtration be provided for the well in accordance with the Surface Water Treatment Rule. A mitigation plan was implemented. This plan included crack surveys, a long-term settlement station monitoring program, and limitation of the groundwater withdrawal rate to 1.0 million gallons per day (mgd) and maximum production rate to 1500 gpm.     

Delineation of groundwater potential zones in Kakund watershed,Eastern Rajasthan,using remote sensing and GIS techniques

The remotely sensed data provides synoptic viewing and repetitive coverage for thematic mapping of natural resources. In the present study hydrogeomorphological mapping has been carried out in Kakund watershed, Eastern Rajasthan for delineating groundwater potential zones. IRS-1D LISS III Geocoded FCC data in conjunction with Survey of India toposheet (1:50000 scale) and field inputs were used for thematic mapping. Geomorphic units identified through visual interpretation of FCC include: alluvial plain, plateau, valley fills, intermontane valleys, burried pediment, residual hills, and linear ridges. In addition, lineaments were mapped since they act as conduit for groundwater recharge. Majority of the lineaments trends NE-SW and a few along NW-SE directions and are confined to the southern and southeastern parts of the watershed. Based on hydrogeomorphological, geological and lineament mapping the Kakund watershed has qualitatively been categorized into four groundwater potential zones, viz. good to very good, moderate to good, poor to moderate and very poor to poor. The study reveals that only 10.97% of the area has good to very good, 35.41% area with moderate to good, 49.04 % of the area has poor to moderatel, while remaining 4.57% has poor to very poor groundwater potential.     

Groundwater potential zonation for basaltic watersheds using satellite remote sensing data and GIS techniques

This paper summarizes the findings of groundwater potential zonation mapping at the Bharangi River basin, Thane district, Maharastra, India, using Satty’s Analytical Hierarchal Process model with the aid of GIS tools and remote sensing data. To meet the objectives, remotely sensed data were used in extracting lineaments, faults and drainage pattern which influence the groundwater sources to the aquifer. The digitally processed satellite images were subsequently combined in a GIS with ancillary data such as topographical (slope, drainage), geological (litho types and lineaments), hydrogeomorphology and constructed into a spatial database using GIS and image processing tools. In this study, six thematic layers were used for groundwater potential analysis. Each thematic layer’s weight was determined, and groundwater potential indices were calculated using groundwater conditions. The present study has demonstrated the capabilities of remote sensing and GIS techniques in the demarcation of different groundwater potential zones for hard rock basaltic basin.     

Hydrogeology and vulnerability map (Epik method) of the “Supramonte” karstic system, north-central Sardinia

The Supramonte limestone complex, of Jurassic–Cretaceous age, lies within the municipal borders of Urzulei, Oliena and Orgosolo (north-central Sardinia). For the most part, the Supramonte groundwater drains towards the outcrops in the northernmost part of the massif. A minor, almost negligible quantity of water drains towards a series of outcrops along the edge of the carbonate structure, with numerous subaerial and submarine springs. The groundwater in the entire system represents one of the most important water resources in Sardinia, especially for drinking purposes. Taking into consideration the development of karst cavities, permanent groundwater reserves were cautiously estimated to be at least 144 Mm³. Intrinsic vulnerability to pollution has been assessed by means of the EPIK method.     

Groundwater potential index in a crystalline terrain using remote sensing data

Demand for groundwater for drinking, agricultural and industrial purposes has increased due to uncertainty in the surface water supply. Agriculture is the main occupation of the rural people in Guntur district, Andhra Pradesh, India. Development of groundwater in the district is very less, indicating a lot of scope for further development of groundwater resources. However, assessment of groundwater conditions, particularly in a crystalline terrain, is a complex task because of variations in weathering and fracturing zones from place to place. Systematic studies for evaluation of groundwater potential zones have been carried out in a crystalline terrain of the district. Information on soils, geological formations and groundwater conditions is collected during the hydrogeological survey. Topographical and drainage conditions are derived from the Survey of India topographical maps. Geomorphological units and associated landform features inferred and delineated from the Indian remote sensing satellite imagery (IRS ID LISS III FCC) are moderately buried pediplain (BPM), shallow buried pediplain (BPS), valley fills (VF), structural hill (SH), residual hills (RH), lineaments and land use/land cover. A groundwater potential index (GPI) is computed for relative evaluation of groundwater potential zones in the study area by integrating all the related factors of occurrence and movement of groundwater resources. Accordingly, the landforms, BPM, BPS, VF, SH and RH, of the area are categorized as very good groundwater potential zone, good to moderate groundwater potential zone, moderate to poor groundwater potential zone, poor to very poor groundwater potential zone and very poor groundwater potential zone, respectively, for development and utilization of both groundwater and surface water resources for eliminating water scarcity. This study could help to improve the agrarian economy for better living conditions of the rural people. Taking the total weight-score of the GPI into account, a generalized classification of groundwater potential zones is evaluated for a quick assessment of the occurrence of groundwater resources on regional scale.     

Vulnerability mapping of shallow groundwater aquifer using SINTACS model in the Jordan Valley area, Jordan

Jordan Valley is one of the important areas in Jordan that involves dense agricultural activities, which depend on groundwater resources. The groundwater is exploited from an unconfined shallow aquifer which is mainly composed of alluvial deposits. In the vicinity of the Kafrein and South Shunah, the shallow aquifer shows signs of contamination from a wide variety of non-point sources. In this study, a vulnerability map was created as a tool to determine areas where groundwater is most vulnerable to contamination. One of the most widely used groundwater vulnerability mapping methods is SINTACS, which is a point count system model for the assessment of groundwater pollution hazards. SINTACS model is an adaptation for Mediterranean conditions of the well-known DRASTIC model. The model takes into account several environmental factors: these include topography, hydrology, geology, hydrogeology, and pedology. Spatial knowledge of all these factors and their mutual relationships is needed in order to properly model aquifer vulnerability using this model. Geographic information system was used to express each of SINTACS parameters as a spatial thematic layer with a specific weight and score. The final SINTACS thematic layer (intrinsic vulnerability index) was produced by taking the summation of each score parameter multiplied by its specific weight. The resultant SINTACS vulnerability map of the study area indicates that the highest potential sites for contamination are along the area between Er Ramah and Kafrein area. To the north of the study area there is a small, circular area which shows fairly high potential. Elsewhere, very low to low SINTACS index values are observed, indicating areas of low vulnerability potential.     

Use of GIS for optimalization of human activity in a catchment area: An example of the Beauce region (France)

The quality of groundwater often represents a limiting factor for its exploitation. The chemical composition of groundwater is a very complicated process involving geochemical, hydrochemical, and biochemical interaction between the water and the rock with which it is in contact. In addition, as a result of human activity, the deterioration of groundwater quality is a serious problem. The use of a geographic information system (GIS) combining various data may help solve this problem. The article describes multicriterion analysis applied to the Beauce basin in France, which is a part of the SAGE project of the BRGM Orléans.     

Application of Bayesian networks for fire risk mapping using GIS and remote sensing data

This study estimates fire risk in Swaziland using geographic information system (GIS) and remote sensing data. Fire locations were identified in the study area from remotely sensed Moderate Resolution Imaging Spectroradiometer (MODIS) active fire and burned area data for the period between April 2000 to December 2008 and January 2001 and December 2008, respectively. A total of thirteen biophysical and socio-economic explanatory variables were analyzed and processed using a Bayesian network (BN) and GIS to generate the fire risk maps. The interdependence of each of the factors was probabilistically determined using the expectation-maximization (EM) learning algorithm. The final probabilistic outputs were then used to classify the country into five fire risk zones for mitigation and management. Accuracy assessments and comparison of the fire risk maps indicate that the risk maps derived from the active fire and burned area data were 93.14 and 96.64% accurate, respectively, demonstrating sufficient agreement between the risk maps and the existing data. High fire risk areas are observed in the Highveld particularly plantation forests and grasslands and within the Lowveld sugarcane plantations. Land tenure and land cover are the dominant determinants of fire risk, the implications of which are discussed for fire management in Swaziland. Limitations of the data used and the modeling approach are also discussed including suggestions for improvements and future research.     

Groundwater vulnerability and risk mapping of the Angad transboundary aquifer using DRASTIC index method in GIS environment

The protection and preservation of groundwater resources are compulsory, particularly in the arid and semiarid countries where the waters are scarce. The effects of increasing urbanization, economic development, and agricultural activities, along with the erratic and scarce rainfall, contribute to the quantitative and qualitative deterioration of these resources. This paper attempts to produce groundwater vulnerability and risk maps for the Angad transboundary aquifer using DRASTIC model. The data which correspond to the seven parameters of the model were collected and converted to thematic maps in Geographic Information System environment. The modified DRASTIC map, which is the summation of the DRASTIC index and the network fractures maps, shows two degreed of vulnerability: medium and high. This map is then integrated with a land use map to assess the potential risk of groundwater to pollution in the Angad transboundary aquifer. There are three risk zones that are identified: moderate, high, and very high.     

Modeling forest fire risk in the northeast of Iran using remote sensing and GIS techniques

Fire in forested areas can be regarded as an environmental disaster which is triggered by either natural forces or anthropogenic activities. Fires are one of the major hazards in forested and grassland areas in the north of Iran. Control of fire is difficult, but it is feasible to map fire risk by geospatial technologies and thereby minimize the frequency of fire occurrences and damages caused by fire. The fire risk models provide a suitable concept to understand characterization of fire risk. Some models are map based, and they combine effectively different forest fire–causing variables with remote sensing data in a GIS environment for identifying and mapping forest fire risk. In this study, Structural Fire Index, Fire Risk Index, and a new index called Hybrid Fire Index were used to delineate fire risk in northeastern Iran that is subjected to frequent forest fire. Vegetation moisture, slope, aspect, elevation, distance from roads, and vicinity to settlements were used as the factors influencing accidental fire starts. These indices were set up by assigning subjective weight values to the classes of the layers based on their sensitivity ratio to fire. Hot spots data derived from MODIS satellite sensor were used to validate the indices. Assessment of the indices with receiver operating characteristic (ROC) curves shows that 76.7 % accuracy of the HFI outperformed the other two indices. According to the Hybrid Fire Index, 57.5 % of the study area is located under high-risk zone, 33 % in medium-risk zone, and the remaining 9.5 % area is located in low-risk zone.     

Groundwater resource exploration in Salem district,Tamil Nadu using GIS and remote sensing

Since last decade, the value per barrel of potable groundwater has outpaced the value of a barrel of oil in many areas of the world. Hence, proper assessment of groundwater potential and management practices are the needs of the day. Establishing relationship between remote sensing data and hydrologic phenomenon can maximize the efficiency of water resources development projects. Present study focuses on groundwater potential assessment in Salem district, Tamil Nadu to investigate groundwater resource potential. At the same, all thematic layers important from ground water occurrence and movement point of view were digitized and integrated in the GIS environment. The weights of different parameters/themes were computed using weighed index overlay analysis (WIOA), analytic hierarchy process (AHP) and fuzzy logic technique. Through this integrated GIS analysis, groundwater prospect map of the study area was prepared qualitatively. Field verification at observation wells was used to verify identified potential zones and depth of water measured at observation wells. Generated map from weighed overlay using AHP performed very well in predicting the groundwater surface and hence this methodology proves to be a promising tool for future.     

Karst groundwater vulnerability mapping: application of a new method in the Swabian Alb, Germany

Groundwater from karst aquifers is an important drinking water resource, which is, however, particularly vulnerable to contamination. Karst aquifers consequently need special protection. This paper discusses the concept of groundwater vulnerability mapping and the special characteristics of karst aquifers that are relevant in this context. On this basis, a new method of groundwater vulnerability mapping is proposed—the PI method. It can be applied for all types of aquifers, but provides special tools for karst. Vulnerability is assessed as the product of two factors: protective cover (P) and infiltration conditions (I). The method was first applied and compared with two other methods (EPIK and the German method) in a test site in the Swabian Alb, Germany. The results obtained with the different methods are discussed and an outlook on the role of vulnerability maps within an overall groundwater protections scheme is given.

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Resumen Las aguas subterráneas en medios kársticos suponen un recurso importante para uso de boca, pero es particularmente vulnerable a la contaminación, por lo que los acuíferos kársticos requieren una protección especial. Este artículo discute el concepto de cartografía de vulnerabilidad de las aguas subterráneas y las características propias de los acuíferos kársticos que son relevantes en este contexto. Con esta base, se propone un nuevo método para cartografiar la vulnerabilidad de las aguas subterráneas, denominado "PI". Puede ser aplicado a todo tipo de acuíferos, pero proporciona herramientas especiales en medios kársticos. Se establece la vulnerabilidad como resultado de dos factores: la cubierta protectora y las condiciones de infiltración. El método ha sido aplicado por vez primera y comparado con otros dos enfoques (EPIK y el método alemán) en un emplazamiento ubicado en Swabian Alb (Alemania). Se discute los resultados obtenidos con estos métodos y se incide en cuál es el papel que desempeñan los mapas de vulnerabilidad en el contexto de los esquemas generales de protección de las aguas subterráneas.

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Résumé L'eau souterraine des karsts est une importante ressource d'eau potable, cependant particulièrement vulnérable à la pollution. C'est pourquoi les aquifères karstiques nécessitent une protection particulière. Ce papier discute le concept de cartographie de la vulnérabilité de l'eau souterraine et les caractéristiques particulières des aquifères karstiques qui sont concernés dans ce contexte. Sur cette base, une nouvelle méthode de cartographie de la vulnérabilité de l'eau souterraine est proposée: la méthode PI. Elle peut être appliquée à tous les types d'aquifères, mais fournit des outils spécifiques au karst. La vulnérabilité est évaluée comme étant le produit de deux facteurs: les conditions de couverture protectrice (P) et d'infiltration (I). La méthode a été mise en oeuvre pour la première fois et comparée à deux autres méthodes (EPIK et la méthode allemande) sur un site test du Jura souabe (Allemagne). Les résultats obtenus avec les différentes méthodes sont discutés et le rôle des cartes de vulnérabilité dans un schéma général de protection des eaux souterraines est passé en revue.

     

Groundwater potentiality mapping in the Sinai Peninsula, Egypt, using remote sensing and GIS-watershed-based modeling

Systematic planning for groundwater exploration using modern techniques is essential for the proper utilization, protection and management of this vital resource. Enhanced Thematic Mapper Plus (ETM+) images, a geographic information system (GIS), a watershed modeling system (WMS) and weighted spatial probability modeling (WSPM) were integrated to identify the groundwater potential areas in the Sinai Peninsula, Egypt. Eight pertinent thematic layers were built in a GIS and assigned appropriate rankings. Layers considered were: rainfall, net groundwater recharge, lithology or infiltration, lineament density, slope, drainage density, depth to groundwater, and water quality. All these themes were assigned weights according to their relative importance to groundwater potentiality and their corresponding normalized weights were obtained based on their effectiveness factors. The groundwater potentiality map was finally produced by WSPM. This map comprises five gradational groundwater potentiality classes ranging from very high to very low. The validity of this unbiased GIS-based model was tested by correlating its results with the published hydrogeological map of Egypt and the actual borehole yields, where a concordant justification was reached. The map declared that the Sinai Peninsula is generally of moderate groundwater potentiality, where this class encompasses an area of 33,120?km² which represents 52% of its total area.     

Assessing soil erosion in Mediterranean karst landscapes of Lebanon using remote sensing and GIS

Maps showing the potential for soil erosion at 1:100,000 scale are produced in a study area within Lebanon that can be used for evaluating erosion of Mediterranean karstic terrain with two different sets of impact factors built into an erosion model. The first set of factors is: soil erodibility, morphology, land cover/use and rainfall erosivity. The second is obtained by the first adding a fifth factor, rock infiltration. High infiltration can reflect high recharge, therefore decreasing the potential of surface runoff and hence the quantity of transported materials. Infiltration is derived as a function of lithology, lineament density, karstification and drainage density, all of which can be easily extracted from satellite imagery. The influence of these factors is assessed by a weight/rate approach sharing similarities between quantitative and qualitative methods and depending on pair-wise comparison matrix.The main outcome was the production of factorial maps and erosion susceptibility maps (scale 1:100,000). Spatial and attribute comparison of erosion maps indicates that the model that includes a measure of rock infiltration better represents erosion potential. Field investigation of rills and gullies shows 87.5% precision of the model with rock infiltration. This is 17.5% greater than the precision of the model without rock infiltration. These results indicate the necessity and importance of integrating information on infiltration of rock outcrops to assess soil erosion in Mediterranean karst landscapes.