Groundwater study using remote sensing and geographic information systems (GIS) in the central highlands of Eritrea

Remote sensing, evaluation of digital elevation models (DEM), geographic information systems (GIS) and fieldwork techniques were combined to study the groundwater conditions in Eritrea. Remote sensing data were interpreted to produce lithological and lineament maps. DEM was used for lineament and geomorphologic mapping. Field studies permitted the study of structures and correlated them with lineament interpretations. Hydrogeological setting of springs and wells were investigated in the field, from well logs and pumping test data. All thematic layers were integrated and analysed in a GIS. Results show that groundwater occurrence is controlled by lithology, structures and landforms. Highest yields occur in basaltic rocks and are due to primary and secondary porosities. High yielding wells and springs are often related to large lineaments, lineament intersections and corresponding structural features. In metamorphic and igneous intrusive rocks with rugged landforms, groundwater occurs mainly in drainage channels with valley fill deposits. Zones of very good groundwater potential are characteristic for basaltic layers overlying lateritized crystalline rocks, flat topography with dense lineaments and structurally controlled drainage channels with valley fill deposits. The overall results demonstrate that the use of remote sensing and GIS provide potentially powerful tools to study groundwater resources and design a suitable exploration plan.An erratum to this article can be found at     

Geological mapping and mining prospecting in the Aouli inlier (Eastern Meseta,Morocco) based on remote sensing and geographic information systems (GIS)

Landsat 8 Oli, ASTER, and Sentinel 2A satellite images processing was used to map geological formations, lineaments and hydrothermal alteration minerals in the Aouli inlier, as a case study to illustrate the application of digital images processing and Geographic Information System (GIS) in geological mapping and mining prospecting. Principal Component Analysis (PCA) applied to the Landsat images allowed good lithological discrimination and contributed to the updating of available geological maps. The Automatic lineament extraction from Sentinel images revealed the main tectonic structures affecting Aouli inlier. The ratio bands (b5+b7)/b6 and the false color composite (b4/b6, b2/b1, b3/b2) allowed the hydrothermal alteration minerals mapping from Aster images. Combined with available geological data and field observations, the satellite derived data were integrated and analyzed in a GIS software to establish mining prospecting guides. The results showed that the anomaly zones are intimately linked to NNE –SSW and NW –SE oriented faults and to highly fractured areas developing argillic and Fe rich alterations. Verified via field survey, this approach was successfully applied to the Aouli inlier to rapidly target potential areas to be explored in the tactical phase. This provides a model for future prospecting efforts for similar mineral deposits in other areas.©2022 China Geology Editorial Office.     

Dynamic analysis of eco-environmental changes based on remote sensing and geographic information system: an example in Longdong region of the Chinese Loess Plateau

The Chinese Loess Plateau is suffering from severe soil erosion. The eco-environmental changes of the plateau are believed to have an important influence on global eco-environmental sustainability; hence, this problem has attracted considerable attention from scientists around the world. This study has two purposes; application of remote sensing (RS) and geographic information system (GIS) techniques in the dynamic analysis of eco-environmental changes in the semiarid zone; and using the Longdong region of the Chinese Loess Plateau as an example, to make dynamic analysis of the eco-environmental changes of the region during the 1986–2004 period and identify controlling factors. Landsat Thematic Mapper (TM) data at a spatial resolution of 30 m were used for analysis. Two training areas were selected in Jingning and Qingcheng counties for analysis using 10-m resolution SPOT and Landsat TM data. The satellite RS images were obtained from the Institute of Remote Sensing Application (IRSA), Chinese Academy of Sciences (CAS). Each images was rectified by Albers Equal Area Conic projection based on 1:50,000 scale topographic maps after spectrum preparation of the images. To make the precision within 1 or 2 pixels, the accurate coordinative control points of the two systems were identified. Then the interpretation key was established based on the land use/cover survey in the study area. The images were classified into six primary environmental types (farmland, forest, grassland, water, construction area, and desert) and 25 sub-types using a visual image interactive interpretation method to obtain vector and attribute data. The resultant accuracy of the land use/cover classification reached 95%. Finally, the transformation areas and ratios of various eco-environmental types in the region were calculated to obtain the transition matrixes of eco-environmental types in the two training areas, Jingning and Qingcheng. This study demonstrates that satellite RS and GIS techniques are effective tools to monitor and analyze the eco-environmental changes in the semiarid region. Visual image interactive interpretation based on GIS technique provides comprehensive information on the direction, rate, and location of eco-environmental changes. The transition matrix model can be used to precisely analyze the variation and rates of the eco-environmental types and their spatial distribution. Great land use changes have taken place Longdong during the 1986–2004 period. These eco-environmental changes were driven by natural and human factors. Natural factors influencing the Longdong region of the Chinese Loess Plateau mainly include temperature, water condition, terrain, soil, and erosion; while human activities include over-cultivation, overgrazing, and fuelwood cutting. As viewed from the extent and severity of the influences, human activities play a very important role in altering the eco-environment of the semiarid region. The study results indicate a need for future research and observation in the semiarid region.     

Mapping potential areas for groundwater storage in the High Guir Basin (Morocco):Contribution of remote sensing and geographic information system

Identification of water potential areas in arid regions is a crucial element for the enhancement of their water resources and socio-economic development. In fact, water resources system-planning can be used to make various decisions and implement management of water resources policies. The purpose of this study is to identify groundwater storage areas in the high Guir Basin by implementing Geographic Information System (GIS) and Remote Sensing methods. The required data for this study can be summarized into five critical factors: Topography (slope), lithology, rainfall, rock fracture and drainage. These critical factors have been converted by the GIS into thematic maps. For each critical parameter, a coefficient with weight was attributed according to its importance. The map of potential groundwater storage areas is obtained by adding the products (coefficient × weight) of the five parameters. The results show that 50% to 64% of the total area of the High Guir Basin is potentially rich in groundwater, where most of fracture systems are intensely developed. The obtained results are validated with specific yield of the aquifer in the study area. It is noted that there is a strong positive correlation between excellent groundwater potential zones with high flows of water points and it diminishes with low specific yield with poor potential zones.     

Groundwater exploration using remote sensing and geographic information systems in a semi-arid area (Southwest of Urmieh, Northwest of Iran)

Shortage of water required for drinking and agricultural uses is a subject with a vital importance in most arid and semi-arid regions. The area of this study is one of the semi-arid regions located in southwest of Urmieh lake, northwest of Iran, between N 37°00′, 37°15′ latitude and E 45°05′, 45°30′ longitude which is composed of Permian dolomitic limestone, limestone, and post-Jurassic granite with a very low primary porosity/permeability character. In order to delineate groundwater potential zones in this area, the study focused on identifying secondary porosity/permeability indicators such as lineaments, vegetation cover, lithology, drainage pattern, drainage density, etc. In this regard, a remote sensing and geographic information system-based methodology was selected. Landsat ETM, IRS (pan), SPOT data, digital elevation model, and digital image processing techniques such as filtering, false color composite, principal component analysis, band rationing and classification have been applied to reach the purposes. Information layers extracted for analysis and interpretation stage were then integrated with other data and modeled through the use of existing geographic information system (GIS) software and their related analytical functions. Finally, based on determined ground water favorability index for different sub zones, layers, weighting, and overlapping, a ground water potential index (GWPI) was defined which respectively was utilized to groundwater potential zoning and preparation of GWPI map of the region. Within the six different sub zones defined, two sub zones labeled with high and very good potential areas were highly recommended for further development and exploration purposes. Geophysical investigations in target areas confirm the labeled subzones. Based on the obtained results of the study, it can be concluded that remote sensing data are very useful tool to extract information of groundwater exploration. Also, application of geographic information systems to find target areas for groundwater exploration are effective to save time and cost.     

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.     

乌拉山地区遥感蚀变信息提取研究

根据研究区蚀变岩在ETM图像上的光谱特征,利用比值增强、主成分分析及比值增强后主成分分析等方法,对内蒙古乌拉山地区蚀变岩信息进行增强,进而采用均值加标准差与最优密度分割相结合的方法对蚀变信息进行提取和分析。通过多层次的筛选和评估,划出真异常区,制作遥感异常图。     

青海哈秀地区遥感地质信息提取及找矿预测

为加强在哈秀地区找矿突破工作,以SPOT-5、ETM＋/TM和DEM等多种数据源为研究对象,采用人机交互式与目视解译相结合的方法,对区内线-环构造进行了解译,利用主成分分析法提取了弱矿化蚀变遥感异常,结合已有区域地质资料进行了分析研究,圈定遥感找矿预测区,一方面为野外地质调查提供丰富的遥感信息,另一方面为该区地质找矿突破工作提供了大量有效信息源,缩短了找矿周期.     

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.

     

Evaluation of effective management plan for an agricultural watershed using AVSWAT model,remote sensing and GIS

In the present investigation, an effort has been made to identify the critical sub-watersheds for the development of best management plan for a small watershed of Eastern India using a hydrological model, namely, AVSWAT2000. A total of 180 combinations of various management treatments including crops (rice, maize ground nut and soybean), tillage (zero, conservation, field cultivator, mould board plough and conventional practices) and fertilizer levels (existing half of recommended and recommended) have been evaluated. The investigation reveled that rice cannot be replaced by other crops such as groundnut, maize, mungbean, sorghum and soybean since comparatively these crops resulted in higher sediment yield. The tillage practices with disk plough have been found to have more impact on sediment yield and nutrient losses than conventional tillage practices for the existing level of fertilizer. Sediment yield decreased in the case of zero tillage, conservation tillage, field cultivator, moldboard plough, and conservation tillage as compare to conventional tillage. Lowest NO₃–N loss was observed in zero tillage in all the fertilizer treatments, whereas field cultivator, moldboard plough and disk plough resulted in increase of NO³–N loss. As compared to conventional tillage, the losses of soluble phosphorus were increased in moldboard plough. The losses of organic nitrogen were also increased as fertilizer dose increased. After zero tillage the conservation tillage preformed better in all the fertilizer treatments as per loss of organic nitrogen and organic phosphorus is concerned. It can be concluded that the sediment yield was found to be the highest in the case of disk plough followed by moldboard plough, field cultivator, conventional tillage, field cultivator and least in zero tillage practices. The nutrient losses were found to be in different order with tillage practices, resulted highest in disk plough tillage practices. In view of sediment yield and nutrient losses, the conservation tillage practice was found to be the best as the sediment yield is less than the average soil loss whereas nutrient loss is within the permissible limit.     

Study on the oasis landscape fragmentation in northwestern China by using remote sensing data and GIS: a case study of Jinta oasis

The purpose of this study is to investigate the oasis landscape fragmentation in northwestern China’s arid regions. Landscape maps of Jinta oasis were compiled by using GIS based on Landsat TM data of 1990 and 2000. Landscape indexes for evaluating fragmentation are patch area, patch density, corridor density and split index. Results indicated many difference. First, between the years 1990 and 2000, the landscape fragmentation in Jinta oasis decreased slightly. Second, the area of the matrix decreased at the class level. The landscape fragmentation of the matrix (bare soil) increased as a result of increased influence of human activities on matrix and was opposite to the irrigated farmland whose area is larger and more aggregated in 2000 than in 1990. Third, dense corridor system is one of the most prominent characteristics of the arid regions. It is one of the key factors resulting in the landscape fragmentation; especially the fragmentation within the same patch types. The corridor density of irrigated farmland, residential area and forestland were quite large in Jinta oasis both in 1990 and 2000. The pattern of Jinta oasis is characterized by agricultural oasis embedded in Gobi and in the desert, where the ecosystem was disturbed strongly by the intense human activities.     

Assessment of suffosion-related hazards in karst areas using GIS technology

This paper describes an application of the geographic information system (GIS) technology to a ground stability assessment in the karst area of Dzerzhinsk, Russia. In the stability analysis, the groundwater level changes in the karst aquifer could cause suffosion sinkholes when the gravitational force was greater than the soil strength. The GIS technology was used to combine various data and to delineate the zones of potential gravitational collapse and suffosion collapse in the area.

Remote sensing and GIS based determination of groundwater dependent ecosystems in the Western Cape, South Africa

Finding the location of groundwater dependent ecosystems (GDEs) is important in determining the extent of restrictions that need to be placed upon the abstraction of groundwater. Remote sensing was combined with geographical information system (GIS) modelling to produce a GDE probability rating map for the Sandveld region, South Africa. Landsat TM imagery identified the areas indicating the probable presence of GDEs and GIS assisted in their delineation. Three GIS models were generated: a GIS model predicting landscape wetness potential (LWP model) based on terrain morphological features; the LWP model was modified to highlight groundwater generated landscape wetness potential (the resulting GglWP model); and a groundwater elevation model was interpolated, combining groundwater level measurements in boreholes in the region with digital elevation model data. Biomass indicators generated from Landsat were classified and combined with the GIS models, followed by field verification of riverine and wetland GDEs. The LWP model provided the most accurate results of the three models tested for GDEs in this region.

Mapping soil erosion susceptibility using remote sensing and GIS: a case of the Upper Nam Wa Watershed,Nan Province,Thailand

Land degradation is still a very common problem in the mountains of Asia because of inappropriate land use practice in steep topography. Many studies have been carried out to map shifting cultivation and areas susceptible to soil erosion. Mostly, estimated soil loss is taken as the basis to classify the level of soil loss susceptibility of area. Factors that influence soil erosion are: rainfall erosivity, soil erodibility, slope length and steepness, crop management and conservation practices. Thus the reliability of estimated soil loss is based on how accurately the different factors were estimated or prepared. As each and every small pixel of our earth surface is different from one area to another, the manner in which the study area was discretized into smaller homogenous sizes and how the most accurate and efficient technique were adopted to estimate the soil loss are very important. The purpose of this study is to produce erosion susceptibility maps for an area that has suffered because of shifting cultivation located in the mountainous regions of Northern Thailand. For this purpose, an integrated approach using RS and GIS-based methods is proposed. Data from the Upper Nam Wa Watershed, a mountainous area of the Northern Thailand were used. An Earth Resources Data Analysis System (ERDAS) imagine image processor has been used for the digital analysis of satellite data and topographical analysis of the contour data for deriving the land use/land cover and the topographical data of the watershed, respectively. ARCInfo and ARCView have been used for carrying out geographical data analysis. The watershed was discretized into hydrologically, topographically, and geographically homogeneous grid cells to capture the watershed heterogeneity. The soil erosion in each cell was calculated using the universal soil loss equation (USLE) by carefully determining its various parameters and classifying the watershed into different levels of soil erosion severity. Results show that during the time of this study most of the areas under shifting cultivation fell in the highest severity class of susceptibility.     

遥感图象处理与信息提取方法的研究

在图象预处理中．为了研究不同处理方法的效果．分别采用了灰度变换、图象平滑和图象锐化等方法,经过比较发现,不同的增强方法对不同的特征地物的效果有明显的差异;在图象信息提取时,分别使用最小距离法、比值法和组合比等方法．采用不同波段的图象组合进行运算,可以依次突出不同的地物信息．从而达到了信息自动识别的目的。     

Use of remote sensing and GIS to determine recharge potential zones: the case of Occidental Lebanon

Water recharge from land surfaces into subsurface media is an essential element in the hydrologic cycle. For a small-scale assessment, experimental approaches are usually followed, however, on a regional scale, this assessment needs to be made into a comprehensive picture where spatial data of the different contributing factors are treated. The case of Occidental Lebanon, with an area of around 5,000 km², was studied by the integration of all factors influencing this hydrologic process. Contributing factors are: lineaments and drainage frequency density, lithologic character, karstic domains and land cover/land use. The determination of these factors was carried out mainly by the application of remote sensing. Satellite images (Landsat 7 ETM &; SPOT) and aerial photos were subjected to several treatment processes using a miscellany of software, mainly ERDAS Imagine and ESRI’s Arc View software. Furthermore, exogenetic data, such as topographic and geologic maps, were utilized. The extracted information for these factors was plotted on maps. The integration of the maps in a GIS allowed deciding their interactive effects. However, each factor had its own degree of effect, i.e., weight, which was also determined in this study. This study is an approach to better estimate and provide qualitative assessments of recharge potential (RP). The resultant map shows the highest recharge potentials towards the elevated regions where karstification is well development. It was found that around 57% of the study area is terrain with very high to high recharge rate values, which a considerable amount of precipitated water is allowed to percolate into subsurface rocks.     

Integrated remote sensing and GIS techniques for biogeochemical characterization of the Tinto-Odiel estuary system,SW Spain

The Tinto-Odiel estuary area in SW Spain presents a high concentration of industrial, agricultural and mining activities that seriously affect water quality, producing significant concentrations in trace metals and other contaminant elements. Previous studies have highlighted the important environmental effect of these contaminated waters discharged into the Gulf of Cadiz, contributing in a marked way to trace-metal concentrations in the Mediterranean Sea by water inflow through the Strait of Gibraltar. A global biogeochemical characterization of these waters was the main objective of a multidisciplinary research study funded by the European Union, in which remote sensing and GIS techniques, among other methodologies, were jointly applied. The main results confirmed the usefulness of this integrated methodological approach as an effective tool for the assessment of current biogeochemical conditions. Digital image processing provided valuable thematic information for temporal hydrodynamic analysis and water quality parameters mapping, which was integrated into a GIS database together with experimental information sampled in oceanographic cruises.     

高植被覆盖区遥感矿化信息提取方法研究

针对吉林省由于植被覆盖、水体、阴影等干扰因素,遥感矿化蚀变信息提取方法繁琐,提取结果不理想的问题,采取主成分分析和比值法相结合,采用遥感蚀变信息多层次分离技术,省去多次掩膜处理,尽可能的保留原始信息,减少了人为因素,提取方法更为简便且准确,为高植被覆盖区遥感矿化蚀变信息提取提供了新思路。     

遥感信息与化探在湘南地区找矿预测中的应用

湘南地区是我国重要的有色金属成矿带之一,在该区针对ETM图像采用主成份分析、掩膜等遥感图像处理方法进行遥感蚀变信息提取,并针对该区的水系沉积物,采用迭代法确定地球化学背景值与异常下限,利用MapGIS、Section及DGSS软件提取化探异常信息,研究了该区的地质成矿背景。结合以上两种方法,圈定找矿靶区,为地质勘察工作明确了找矿的方向。