Identification of illegal groundwater pumping in semi-confined aquifers

Abstract

Illegal pumping from underground reservoirs is approached as an inverse problem. The procedure seeks among a set of suspected potential areas the ones from which water is effectively pumped out (or in) and at what rate does this take place? Influence coefficient and finite element are combined in order to simulate the aquifer response to hypothetical pumping scenarios. Then the optimal scenario which makes of simulated head distribution the best fit to the observed headset is retained as solution to the foregoing question. This optimal scenario is derived by minimizing the classical least squares error using the Levenberg-Marquardt Algorithm (LMA). Under the conditions of the treated aquifer example it is observed that LMA is non-convergent unless a regularizing measure is taken during the calculation of the correction applied to the parameter-vector between two successive iterations. The procedure is tested with uniform and non-uniform pumping. In both cases, it yields good identified pumping rates within the observation period, but its performance deteriorates markedly for the rates corresponding to the days when no monitoring well is yet active.

Citation Saffi, M. & Cheddadi, A. (2010 Saffi, M. 2008. Contribution of Influence Coefficients in Solving Groundwater Problems, Rabat, Morocco: Mémoire d'Habilitation Universitaire, Ecole Mohammadia d'Ingénieurs.  [Google Scholar]) Identification of illegal groundwater pumping in semi-confined aquifers. Hydrol. Sci. J. 55(8), 1348–1356.     

Influence of geological structures on groundwater accumulation and groundwater salinity in Musandam Peninsula,UAE and Oman

The hydrological setting and groundwater quality of Musandam Peninsula was studied to investigate the influence of geological structures on the groundwater accumulation and groundwater salinity. Five sets of modified morphometric maps were used to reduce errors and carry out the geological structures. The modification was modified by applying mean filter to the Digital Elevation Model (DEM) then applying Soble filter with 10% threshold and equalization enhancement. D8 and algorithms were used to reveal the drainage basins and drainage networks of the entire area. The algorithm determines into which neighbouring pixel any water in a central pixel will flow naturally. Flow direction in a DEM is calculated for every central pixel of input blocks of a 3 × 3 window, all the time comparing the value of the central pixel in the window with the value of its eight neighbours. The spatial association between geological structures and drainage networks was studied using 2D graph and rose diagrams. Flood basin model was applied to simulate the Arabian Gulf water intrusion into the coastal aquifer. The concentrations of solutes in groundwater samples collected from Wadi Al Bih well field and well locations were correlated with the geological structure trends and intersections. The results of the study reveal that the drainage basins, drainage network and groundwater quality are structurally controlled by subsurface geological structure displacements.     

Finding Science with Science: Evaluating a Domain and Scientific Ontology User Interface for the Discovery of Scientific Resources

Current approaches to the discovery of scientific resources (publications, data sets and web services) are dominated by keyword search. These approaches do not allow scientists to search on the deeper semantics of scientific resources, or to discover resources on the basis of the scientific approaches taken. This article evaluates a user interface that allows users to discover scientific resources through structured knowledge in the form of ontologies describing the domain and the scientific knowledge inherent within the scientific resource, and also through informal user tags. These combined capabilities provide scientists with new and powerful options for resource discovery. A qualitative user evaluation explored how scientists felt about the approach for resource discovery in the context of their scientific work. The study showed that marine scientists were enthusiastic about the capabilities of such an approach and appreciated the ability to browse the visual structure of the knowledge and query on scientific method but, overall, preferred the use of tags over ontologies. The exploratory nature of the user study was used to identify future directions for such improvements.     

Geochemical characteristics and spectrometric prospecting in the muscovite-bearing pegmatites and granites,southeastern Aswan,Egypt

Rare metal mineralization of Sn, Nb-Ta and W is encountered in the Gebel Dihmit area （GDA）, southeastern Aswan, Egypt. The mineralization is related to muscovite granites and their pegmatite derivatives. The pegmatites are divided into three types according to their main mineral assemblages： K-feldspar-muscovite-tourmaline, K-feldspar-albite-muscovite and albite-K-feldspar-lepidolite veins. Petrogenetic studies indicate that Sn and Nb-Ta mineralization extends from the late-magmatic stage to the pegmatite and hydrothermal stages of the （GDA） suite. The albite-K-feldspar-lepidolite granite is composed dominantly of albite, lepidolote, and quartz, with topaz, K-feldspar and amblygonite. The accessory minerals are zircon, monazite, pollucite, columbite-tantalite, microlite and Ta-rich cassiterite. Phenocrysts of quartz, topaz and K-feldspar contain abundant inclusions of albite laths and occasional lepidolite crystals along growth zones （snowball texture）, indicating simultaneous crystallization from a subsolvus, residual magma. The origin of the pegmatites is attributed to extreme differentiation by fractional crystallization of a granitic magma. The economic potential for rare metals was evaluated in the geochemical discrimination diagrams. Accordingly, some of the pegmatites are not only highly differentiated in terms of alkalis, but also the promising targets for small-scale Ta and, to a less extent, Sn. The pegmatites also provide the first example of Fe-Mn and Nb-Ta fractionation in successive generations of granites to cassiterite-bearing pegmatites, which perfectly ex- hibit similar fractionation trends established for primary columbite-tantalite in the corresponding categories of pegmatites. Uranium and Th of magmatic origin are indicated by the presence of thorite and allanite, whereas evidence of hydrothermal mineralization is the alteration of rock- foring minerals such as feldspar and the formation of secondary minerals such as uranophane..     

Salt response of the freshwater microalga Scenedesmus obliquus (Turp.) Kutz is modulated by the algal growth phase

Growth and biochemical responses of the coenobial green alga Scenedesmus obliquus to salinity stress were monitored across different phases of growth. The alga was cultured on BG11 growth medium and subjected to 0, 30, 100, and 200 mmol/L NaCl for a period of 20 d, during which algal cultures were harvested at 4-d intervals. The salinity-induced inhibition of algal growth was accompanied with prolongation of timing of the different growth phases. The sharp and progressive salinity-induced inhibition of algal growth rate during the early phase of growth points to salt shock but moderation of inhibition at the subsequent stages of growth means algal acclimation to salinity. The concentrations of chlorophylls a and b, soluble sugars, proteins as well as those of K+ and Na+ in the alga exhibited peaks at the initiation of the exponential phase of growth, with increasing magnitude in proportion to the increase in the level of salinity. Nevertheless, whereas soluble sugars of the alga peaked at initiation of the exponential phase, starch concentration progressively increased with culture age, reaching saturation towards the stationary phase. Whereas the salinity-induced increase in soluble sugars was most evident at the early stages of growth the reverse was true for starch. The present results point to fast acclimation of S. obliquus to salt stress post a brief salt shock, utilizing soluble sugars, K+ and Na+ for osmotic adjustment. Increasing salinity from 0 to 200 mmol/L NaCl led to progressive increase in soluble sugars, proteins, K + and Na + concentrations of the algal cells, particularly at the early stages of growth. However, the salinity-induced increase in chlorophyll concentration approached a limit at 100 mmol/L NaCl whereas that in starch concentration was more evident at the later stages of growth.     

Fusion of RADARSAT-2 and multispectral optical remote sensing data for LULC extraction in a tropical agricultural area

In this study, we investigated the performance of different fusion and classification techniques for land cover mapping in Hilir Perak, Peninsula Malaysia using RADAR and Landsat-8 images in a predominantly agricultural area. The fusion methods used are Brovey Transform, Wavelet Transform, Ehlers and Layer Stacking and their results classified into seven different land cover classes which include (1) pixel-based classifiers (spectral angle mapper (SAM), maximum likelihood (ML), support vector machine (SVM)) and (2) Object-based (rule-based and standard nearest neighbour (NN)) classifiers. The result shows that pixel-based classification achieved maximum accuracy of the optical data classification using SVM in Landsat-8 with 74.96% accuracy compared to SAM and ML. For multisource data classification, the highest overall accuracy recorded for layer stacking (SVM) was 79.78%, Ehlers fusion (SVM) with 45.57%, Brovey fusion (SVM) with 63.70% and Wavelet fusion (SVM) 61.16%. And for object-based classifiers, the overall classification accuracy is 95.35% for rule-based and 76.33% for NN classifier, respectively. Based on the analysis of their performances, object-based and the rule-based classifiers produced the best classification accuracy from the fused images.     

Land surface temperature and emissivity estimation for Urban Heat Island assessment using medium- and low-resolution space-borne sensors: A review

The Urban Heat Island (UHI) phenomenon, a typical characteristic on urban landscapes, has been recognised as a key driver to the transformation of local climate. Reliable retrieval of urban and intra-urban thermal characteristics using satellite thermal data depends on accurate removal of the effects of atmospheric attenuations, angular and land surface emissivity. Several techniques have been proposed to retrieve land surface temperature (LST) from coarse resolution sensors. Medium spatial resolution sensors like the Advanced Space-borne Thermal Emission and Reflection Radiometer and the Landsat series offer a viable option for assessing LST within urban landscapes. This paper reviews the theoretical background of LST estimates from the thermal infrared part of the electromagnetic spectrum, LST retrieval algorithms applicable to each of the commonly used medium-resolution sensors and required variables for each algorithm. The paper also highlights LST validation techniques and concludes by stipulating the requirements for LST temporal and spatial configuration.     

Contribution of Landsat 8 data for the estimation of land surface temperature in Batna city,Eastern Algeria

In this study, we presented a mono-window (MW) algorithm for land surface temperature retrieval from Landsat 8 TIRS. MW needs spectral radiance and emissivity of thermal infrared bands as input for deriving LST. The spectral radiance was estimated using band 10, and the surface emissivity value was derived with the help of NDVI and vegetation proportion parameters for which OLI bands 5 and 4 were used. The results in comparison with MODIS (MOD11A1) products indicated that the proposed algorithm is capable of retrieving accurate LST values, with a correlation coefficient of 0.850. The industrial area, public facilities and military area show higher surface temperature (more than 37 °C) in comparison with adjoining areas, while the green spaces in urban areas (34 °C) and forests (29 °C) were the cooler part of the city. These successful results obtained in the study could be used as an efficient method for the environmental impact assessment.