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1

Assessment of the vulnerability and sensitivity of groundwater for drinking water supply and irrigation: The case of the Mitidja alluvial aquifer (Northern Algeria)

Khelfi Mohamed El Amine, Hallal Dahbia Djoudar, Guastaldi Enrico, Alili Malika, Nadri Mohamed

Geomatics, Landmanagement and Landscape

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2025

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no. 1

119-145

EN

The aim of this study is to combine the hydrochemical data, geostatistical methods, and numerical approaches with the water pollution vulnerability index of the Mitidja alluvium. This index is obtained by applying the DRASTIC model and a numerical rating system to develop a methodology based on the water sensitivity index. The socio-economic development has led to the overexploitation of groundwater and surface water resources, coupled with insufficient rainfall, which has exacerbated the sensitivity and vulnerability of this precious resource. Compared to previous studies, the most recent sensitivity map serves as an important decision support tool for relevant authorities. According to the survey, this index was very low, accounting for 45.43% of the total drinking water area in 2010. It decreased to 8.25% and later increased to 28.06% in 2018. The high and very high sensitivity index to water pollution (SI) accounted for 5.34% and 9.87% in 2010, and 19.77% and 15.78% in 2018. The variation in irrigation water sensitivity was similar that of drinking water sources (DWS). The medium and high sensitivity indices (SI) increased from 27.21% and 18.20% to 37.19% and 42.01%, reflecting a significant and alarming increase in groundwater sensitivity, vulnerability, and pollution within the study area. The results of the geostatistical approach yielded some interesting results, considering the water intended for drinking water supply and the water intended for irrigation separately in the Mitidja alluvial aquifer.

PL

Celem tego badania jest połączenie danych hydrochemicznych, metod geostatystycznych i podejść numerycznych ze wskaźnikiem podatności na zanieczyszczenie wody aluwium Mitidja. Wskaźnik ten uzyskano poprzez zastosowanie modelu DRASTIC i numerycznego systemu oceny w celu opracowania metodologii opartej na wskaźniku wrażliwości wody. Rozwój społeczno-gospodarczy doprowadził do nadmiernej eksploatacji zasobów wód gruntowych i powierzchniowych, w połączeniu z niewystarczającymi opadami deszczu, co zaostrzyło wrażliwość i podatność tego cennego zasobu. W porównaniu z poprzednimi badaniami najnowsza mapa wrażliwości służy jako ważne narzędzie wspomagające podejmowanie decyzji dla odpowiednich organów. Według badania wskaźnik ten był bardzo niski i stanowił 45,43% całkowitej powierzchni wody pitnej w 2010 r. Zmniejszył się do 8,25%, a następnie wzrósł do 28,06% w 2018 r. Wysoki i bardzo wysoki wskaźnik wrażliwości na zanieczyszczenie wody (SI) stanowił 5,34% i 9,87% w 2010 r. oraz 19,77% i 15,78% w 2018 r. Zmienność wrażliwości wody nawadniającej była podobna do zmienności źródeł wody pitnej (DWS). Średnie i wysokie wskaźniki wrażliwości (SI) wzrosły z 27,21% i 18,20% do 37,19% i 42,01%, co odzwierciedla znaczny i alarmujący wzrost wrażliwości, podatności i zanieczyszczenia wód gruntowych na badanym obszarze. Wyniki podejścia geostatystycznego przyniosły interesujące rezultaty, biorąc pod uwagę osobno wodę przeznaczoną do zaopatrzenia w wodę pitną i wodę przeznaczoną do nawadniania w warstwie wodonośnej aluwialnej Mitidja.

2

Geostatystyka dla niematematyków. Przewodnik praktyczny – część I

Naworyta Wojciech

Przegląd Geologiczny

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2024

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Vol. 72, nr 7

341--349

EN

Geostatistical tools are useful and even necessary in many fields, not only in geology. The obstacle to their widespread use is the seemingly difficult mathematical foundations with which the teaching of the subject usually begins. Many years of experience and observations allow me to claim that even if geostatistical methods are used, they are often incomplete and imperfect. In a series of three articles, I would like to introduce potential non-mathematicians to the most important methods and tools from the arsenal of spatial statistics and how to use them properly. I will indicate the areas where they can be used, explain whether they can always be used, showwhat decisions should be made during calculations and how to interpret the obtained results. It will not be a compendium, but rather a pocket guide facilitating the reader's first contact with geostatistics. In the first article, in the introduction, I will explain where the title comes from; I will show what geostatistics can be useful for; what is interpolation, is it always possible, when does it make sense and what does its accuracy depend on? I will show how imperfect the research material available to a geologist is and why we should use sophisticated software to solve seemingly simpleproblems. Using a non-obvious example, I will try to explain the phenomenon of autocorrelation, which is important in geostatistics. I will also ask a few questions, the answers to which will be in the next article in this series.

3

Geostatystyka dla niematematyków. Przewodnik praktyczny – część III

Naworyta Wojciech

Przegląd Geologiczny

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2024

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Vol. 72, nr 9

451--459

EN

Geostatistical tools are useful and even necessary in many fields, not only in geology. The obstacle to their widespread use is the seemingly difficult mathematical foundations with which the teaching of the subject usually begins. Many years of experience and observations allow me to claim that even if geostatistical methods are used, they are often incomplete and imperfect. In a series of three articles, I would like to introduce potential non-mathematicians to the most important methods and tools from the arsenal of spatial statistics and how to use them properly. I will indicate the areas where they can be used, explain whether they can always be used, show what decisions should be made during calculations and how to interpret the obtained results. It will not be a compendium, but rather a pocket guide facilitating the reader ’s first contact with geostatistics. In the third article of my series, I will present the kriging procedure - an interpolation method based on geostatistical assumptions. I will list the most important activities and decisions that need to be made when using this method. Creating a model using the kriging method is the basic goal of using geostatistical methods, so in this article I will make extensive use of the content I presented earlier, from interpolation through autocorrelations to the variogram. The latter serves as an important tool in kriging. Using the example of a lignite deposit model, I will show how to interpret the model and the model credibility map.

4

Geostatystyka dla niematematyków. Przewodnik praktyczny – część II

Naworyta Wojciech

Przegląd Geologiczny

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2024

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Vol. 72, nr 8

391--398

EN

Geostatistical tools are useful and even necessary in many fields, not only in geology. The obstacle to their widespread use is the seemingly difficult mathematical foundations with which the teaching of the subject usually begins. Many years of experience and observations allow me to claim that even if geostatistical methods are used, they are often incomplete and imperfect. In a series of three articles, I would like to introduce potential non-mathematicians to the most important methods and tools from the arsenal of spatial statistics and how to use them properly. I will indicate the areas where they can be used, explain whether they can always be used, show what decisions should be made during calculations, and how to interpret the obtained results. It will not be a compendium, but rather a pocket guide facilitating the reader ’s first contact with geostatistics. In this, the second article of a three-part series, I will focus on the variogram - the most important tool in geostatistics. I will show what is hidden behind the mathematical formula and what information about the analysed spatial phenomenon can be obtained only using a variogram. In the third article, I will present another useful function of the variogram. It will act as a tool in the process of geostatistical interpolation using the kriging method.

5

Geostatystyka dla niematematyków. Przewodnik praktyczny – appendix

Naworyta Wojciech

Przegląd Geologiczny

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2024

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Vol. 72, nr 12-1

685--691

EN

Geostatistical tools are useful and even necessary in many fields, not only in geology. The obstacle to their widespread use is the seemingly difficult mathematical foundations with which the teaching of the subject usually begins. Many years of experience and observations allow me to claim that even if geostatistical methods are used, they are often incomplete and imperfect. In a series of three articles, I tried to familiarize potential non-mathematicians with the most important methods and tools from the arsenal of spatial statistics and how to use them properly. I indicated the areas where these methods can be used, explained whether they can always be used, showed what decisions should be made during calculations and how the results obtained should be interpreted. It is not a compendium, but rather a pocket guide facilitating the reader's first contact with geostatistics. After publishing my triptych under the common title "Geostatistics for non-mathematicians", I decided to add a supplement in which I will discuss several important issues. These include the condition of stationarity, the problem of the presence of a trend in the variability of the analysed phenomenon, and the situation where there are observations that differ significantly from the others, called outliers.

6

Skala projektów elektrowni fotowoltaicznych w Polsce – wstępne badanie geostatystyczne na podstawie bazy OOŚ

Pelczar Szymon

Polish Journal for Sustainable Development

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2024

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T. 28, nr 2

53--62

PL

Moc zainstalowana systemów fotowoltaicznych w Polsce systematycznie wzrasta. Choć w strukturze rodzajów jednostek wytwórczych tego typu dominują mikroinstalacje, to swój udział ustawicznie zwiększają także instalacje wielkoskalowe – elektrownie fotowoltaiczne. Systemy te nie pozostają bez wpływu na środowisko, a ich realizacja niejednokrotnie napotyka konflikty społeczne. Praca miała na celu oszacowanie skali elektrowni fotowoltaicznych w Polsce przy zastosowaniu danych dostępnych w bazie ocen oddziaływania na środowisko (z wykorzystaniem analizy geostatystycznej). Wyniki badania potwierdzają znacząca liczbę planowanych do realizacji elektrowni fotowoltaicznych, przy czym widoczne jest ich zróżnicowanie przestrzenne w skali regionalnej. Ponadto wynik analizy geostatystycznej dowodzi, że najliczniejszą grupę projektów stanowią te o mocy poniżej 20 MW. Pomimo stosunkowo małej liczby projektów o mocy powyżej 50 MW, mogą mieć one istotny wkład pod względem mocy zainstalowanej systemów fotowoltaicznych.

EN

The installed capacity of photovoltaic systems in Poland is steadily increasing. Although micro-installations dominate in the structure of the types of generating units of this type, large-scale installations - photovoltaic power plants - are also steadily increasing their share. These systems are not without environmental impact, and their implementation often encounters social conflicts. The work aimed to estimate the scale of photovoltaic power plants in Poland using data available in the environmental impact assessment database (using geostatistical analysis). The results of the study confirm a significant number of photovoltaic power plants planned to be built, with apparent spatial variation on a regional scale. In addition, the result of the geostatistical analysis proves that the most numerous group of projects are those with a capacity of less than 20 MW. Despite the relatively small number of projects with a capacity of more than 50 MW, they can make a significant contribution in terms of the installed capacity of photovoltaic systems.

7

Mapping and Assessment of Within-Field Spatial Variability of Soil pH, Electrical Conductivity, and Particle Size Distribution to Delineate Management Zones

Buladaco Marcial S. II, Tandugon Hannah Mae F., Bunquin Michelle Anne B., Sanchez Pearl B., Bugia Sophia Alelie C., Yales Nicole Ann P., Casacop Sarah M.

Ecological Engineering & Environmental Technology

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2024

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Vol. 25, iss. 10

75--86

EN

The study aimed to evaluate the spatial distribution of soil pH, electrical conductivity (EC), and particle size distribution within a seven-hectare field in Los Baños Laguna, Philippines using the ordinary kriging method and to utilize the interpolated maps to delineate management zones. Fifty soil samples were collected from the surface layer at a depth of 0–20 cm using a random sampling technique. On the basis of the obtained results, it was found that the area has an acidic pH, medium-textured soil with low soluble salt content. Geostatistical analysis revealed that soil EC and clay content exhibited strong spatial dependence, while soil pH and silt were observed to have a moderate spatial dependence. In contrast, sand exhibited weak spatial dependence. The spherical model was identified as the optimal fit for soil pH, clay content, silt content, and sand content, while the exponential model was deemed most suitable for EC. Three distinct management zones (MZs) were delineated based on the spatial variability of the selected properties. MZ1, the largest zone covering 82.10% of the area, is characterized by a weakly acidic, clay loam soil while MZ2, comprising 15.11% of the area, has a weakly acidic loam soil. MZ3, the smallest zone occupying 2.79% of the area, has a highly acidic loam soil and may require frequent as well as intensive lime applications. These findings highlight the varied spatial dependency and distribution of soil characteristics even in a relatively small area and the usefulness of the interpolated maps as a valuable tool to identify specific management zones.

8

Application of geostatistical methods in the study of algae in water reservoirs: a review

Zawadzki Jarosław, Fabijańczyk Piotr

Ecological Chemistry and Engineering. S

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2024

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Vol. 31, nr 4

473--491

EN

The growing pollution of aquatic environments, primarily of anthropogenic origin, combined with global climate change, has led to significant increases in eutrophication. This process often results in harmful algal blooms (HABs) of phytoplankton and algae in various water bodies, including inland lakes, marshes, rivers, seas, and oceans. These blooms pose a serious threat not only to aquatic ecosystems but also to human health. Understanding phytoplankton and algal blooms is inherently complex, as these phenomena manifest on multiple spatial and temporal scales. Comprehensive studies of phytoplankton and algae require the collaboration of scientists from diverse scientific disciplines, including biology, ecology, and environmental science. One of the critical tools in this multidisciplinary approach is geostatistics, an advanced and continuously evolving branch of statistics that specialises in analysing spatial and temporal phenomena. Geostatistics is particularly well-suited for the study of phytoplankton and algal blooms due to its ability to handle data that varies across different scales and locations. This review presents and discusses selected studies that employ geostatistical methods to investigate plankton and algae in various water bodies. It highlights the most significant scientific works that, in the authors’ opinion, represent milestones in the application of these studies. Furthermore, various geostatistical methods are explored, ranging from variography to spatiotemporal modelling, providing insights into spatial and temporal patterns and their variability of phytoplankton and algal blooms in aquatic ecosystems.

9

A grade control method without sampling preparation based on spectrometric techniques and the use of electronic detonators in an open pit tungsten deposit

Martín Ruben Alcalde, Diego Isidro, Castañón César, Alonso Teresa

Archives of Mining Sciences

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2023

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Vol. 68, no. 4

587--601

EN

Grade control is crucial for ensuring that the quality of extracted ore aligns with the geological model and mining plan. This process optimises production, reduces dilution, and maximises profits. It involves geological modelling, sampling, assaying, and data analysis. However, adhering to short-term planning in mining operations can be challenging due to operational bottlenecks that arise during the grade control process and blast design, along with their associated costs. Industry standards for grade control require acquiring extensive information and knowledge to achieve a high level of certainty, which takes time. Despite that, time constraints may necessitate making decisions under risk with incomplete information. In such cases, it is important to consider the opportunities, risks, likelihood, consequences, and potential success associated with each alternative. This study presents the testing results of alternative quantitative analytical methods on samples from the Barruecopardo tungsten deposit in Spain. Spectrometric techniques, including Delayed Gamma Neutron Activation Analysis (DGNAA), Laser-induced Breakdown Spectroscopy (LIBS), and Field Portable X-ray Fluorescence (FPXRF), were employed to determine the tungsten content. Based on the findings of this investigation, a real-time decision-making tool for grade control in open-pit mining has been developed. This tool utilises representative samples directly from the blasting debris, considering the inherent risks and uncertainties associated with the process.

10

Estimating the 3-D spatial distribution of mechanical properties of rock by seismic data and well logs

Darjani Mohsen, Bakhtiyari Ehsan, Sen Souvik, Abioui Mohamed

Acta Geophysica

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2023

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Vol. 71, no. 5

2089--2106

EN

The rock mechanical properties influence the selection of drilling parameters, optimized drilling trajectory, and appropriate hydraulic fracturing intervals. Estimating the 3-D spatial distribution of these geomechanical properties at the reservoir scale is a challenging task, especially in the case of limited data only at the well locations. Advanced geostatistical techniques can be utilized to represent a reservoir’s inherent spatial variation more realistically. In this study, we investigate the spatial variability of rock mechanical properties, including Young’s modulus, shear modulus, bulk modulus, and Poisson’s ratio, as major constituents of the reservoir geomechanical model. The data are extracted from a hydrocarbon field located southwest of Iran and consist of forty wells. We first build a 1-D model of rock elastic moduli at each well by integrating petrophysical and core-based laboratory measurements and then develop a corresponding 3-D model using geostatistical simulation techniques. Thereafter, 3-D seismic data are employed to optimize the geomechanical model. Results show that the integration of well logs with seismic data increases the accuracy of field-wise 3-D elastic moduli models. Furthermore, we used various co-simulation techniques to demonstrate the improving effect of complementary data in constructing a more realistic reservoir geomechanical model.

11

On the influence of the nugget effect on the efficiency of magnetometric soil surface screening

Zawadzki Jarosław, Fabijańczyk Piotr

Ecological Chemistry and Engineering. S

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2022

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Vol. 29, nr 4

525--535

EN

The paper presents selected aspects of calculations and modelling of variograms from measurements of soil surface magnetic susceptibility for rapid screening of surface soil contamination with Technogenic Magnetic Particles (TMP). In particular, the methodology of variogram analysis in the case of multiple magnetometric measurements in one measurement location with the use of the MS2D Bartington sensor was discussed. A new approach to analysing such measurements was proposed that allows determining and using the nugget effect from standard, already existing measurements. This is of key importance for the quality of spatial analyses, and thus the screening results obtained by means of field magnetometry. In the paper, it was shown, step by step, that averaging the measurements performed at one measurement point during the calculation of the empirical variograms does not result in the loss of information on spatial variability in the microscale. As it was calculated non-averaged measurements were characterised by the nugget-to-sill ratio of about 96 % which was much higher than in the case of averaged measurements (close to 0 %). A range of correlation was similar in both cases and was equal to about 300 m - 400 m. The local variogram revealed a range of correlation of about 80 cm. As a result, the screening results are more reliable than is the case with the traditional procedure. An additional advantage of the work was the performance of all calculations in free R software.

12

Geostatistical analysis of spatial variability of the liquefaction potential – Case study of a site located in Algiers (Algeria)

Bouguerba Salah Eddine, Zandagui Djawad, Benhchilif Souad

Studia Geotechnica et Mechanica

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2021

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Vol. 43, nr 2

155-168

EN

The city of Algiers (Algeria) is a highly seismic area, and therefore, soil liquefaction poses a major concern for structures resting on sandy soil. A campaign of 62 static penetration tests or cone penetrometer tests (CPT) was carried out on a site located in the commune of Dar El Beïda in Algiers. The soil Liquefaction Potential Index (LPI) values were assessed, for each borehole, based on the simplified procedure of Seed and Idriss. On the other hand, the geographic information system and geostatistical analysis were used to quantify the risk of soil liquefaction at the studied site. It is worth mentioning that the (LPI) was taken as a regionalized variable. In addition, the experimental variogram was modeled on the basis of a spherical model. Also, the interpolation of the LPI values in the unsampled locations was performed by the Kriging technique using both isotropic and anisotropic models. Kriging standard deviation maps were produced for both cases. The cross-validation showed that the anisotropic model exhibited a better fit for the interpolation of the values of the soil liquefaction potential. The results obtained indicated that a significant part of the soil is liable to liquefy, in particular in the northwestern region of the study area. The findings suggest that there is a proportional relationship between the risk of liquefaction and the increase or decrease in seismic acceleration.

13

Zmienność parametrów fizykochemicznych torfów w strefie przypowierzchniowej torfowiska w dolinie Strugi Wodnej (Wysoczyzna Lubartowska)

Rydelek Paweł

Przegląd Geologiczny

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2021

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Vol. 69, nr 12

867--872

EN

The paper presents the results of research on variability of basic physical and chemical parameters of peats from a small fen in the Struga Wodna valley on the Lubartów Plateau. The variability of organic matter content, moisture content, pH and cation exchange capacity (CEC) was analysed. Apart from descriptive statistics, geostatistical methods were also used, including the analysis of semivariograms. All determined parameters showed high variability, including spatial variability. The analysis of the semivariograms showed that for each of the parameters there is a nugget effect, indicating high local variability. The statistically highest variability, expressed by the coefficient of variation, was shown by peat moisture content, while the moisture content showed the highest spatial autocorrelation. The use of geostatistical methods allowed identifying zones with different properties within the fen, and describing the spatial autocorrelation of individual parameters.

14

Monitoring of Groundwater Quality With Cokriging of Geochemical and Geoelectrical Measurements

Zawadzki Jarosław, Fabijańczyk Piotr, Treichel Wiktor

Multidisciplinary Aspects of Production Engineering

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2021

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Vol. 4, Iss. 1

97--106

EN

The study presents the possibility of using geostatistical methods for monitoring groundwater quality. Poland is one of the largest copper producers in the world. However, the extraction and production of copper requires constant care for the natural environment. Reservoir Żelazny Most which is situated in South – Western Poland was designed to store flotation tailings out of nearby copper mines. It is one of the biggest industrial dumps in the world. The reservoir stores huge amounts of tailings and industrial water. Water migrating from dump to groundwater could be a potential source of contamination with chlorides, sulphates, heavy metals, and other hazardous substances used in ore separation process in the copper mining industry, like detergent and phenols. Monitoring system around Żelazny Most dump, which was designed to track harmful substances concentrations in groundwater, contains measuring wells and piezometers. They are used to collect groundwater samples for chemical analyses. The idea of the study was to integrate information provided by chemical analyses and geoelectrical measurements by cokriging method, utilizing correlation between electrical resistance of the soil solution and total dissolved solids concentration in groundwater. This enabled to obtain spatial distribution of total dissolved solids concentrations in groundwater at the part of eastern foreground of Żelazny Most dump.

15

Application of the Triple Diagram Method in forecasting lake water level, on the example of Lake Charzykowskie

Piasecki Adam, Witkowski Wojciech T.

Journal of Water and Land Development

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2021

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no. 51

11--16

EN

The work focused on forecasting changes in lake water level. The study employed the Triple Diagram Method (TDM) using geostatistical tools. TDM estimates the value by information from an earlier two periods of observation, refers as lags. The best results were obtained for data with an average a 1-week lag. At the significance level of 1σ, a the forecast error of ±2 cm was obtained. Using separate data for warm and cold months did not improve the efficiency of TDM. At the same time, analysis of observations from warm and cold months explained trends visible in the distribution of year-round data. The methodology, built on case study and proposed evaluation criteria, may function as a universal solution. The proposed methodology can be used to effectively manage water-level fluctuations both in postglacial lakes and in any case of water-level fluctuation.

16

Geospatial Assessment of Soil Organic Matter Variability at Sidi Bennour District in Doukkala Plain in Morocco

Bouasria Abdelkrim, Ibno Namr Khalid, Rahimi Abdelmejid, Ettachfini El Mostafa

Journal of Ecological Engineering

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2021

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Vol. 22, nr 11

120--130

EN

Understanding the spatial variability of soil organic matter (SOM) is critical for studying and assessing soil fertility and quality. This knowledge is important for soil management, which results in high crop yields at a reduced cost of crop production and helps to protect the environment. The benefits of an accurate interpolation of SOM spatial distribution are well known at the agricultural, economic, and ecological levels. It has been conducted this study for comparing and analyze different spatial interpolation methods to evaluate the spatial distribution of SOM in Sidi Bennour District, which is a semi-arid area in the irrigated scheme of the Doukkala Plain, Morocco. For conding this study, it was collected 368 representative soil samples at a depth of 0–30 cm. A portable global positioning system was used to obtain the location coordinates of soil sampling sites. The SOM spatial distribution was performed using four interpolation methods: inverse distance weighted and local polynomial interpolation as deterministic methods, and ordinary kriging and empirical Bayesian kriging as geostatistical methods. High SOM levels were concentrated in vertisols, and low SOM levels were observed in immature soils. The average SOM value was 1.346%, with moderate to high variability (CV = 35.720%). A low SOM concentration indicates a continuous possibility of soil degradation in the future. Ordinary kriging yielded better results than the other interpolation methods (RMSE = 0.395) with a semivariogram fitted by an exponential model, followed by inverse distance weighted (RMSE = 0.397), empirical Bayesian kriging (RMSE = 0.400), and local polynomial interpolation (RMSE = 0.412). Soil genetics and the strong influence of human activity are the major sources of SOM spatial dependence, which is moderate to low. Low SOM content levels (< 1.15%) were present in the southwestern and eastern parts of the digital map. This situation calls for the implementation of specific soil recovery measures.

17

Kriging – od górniczej praktyki poprzez teorię do zastosowań środowiskowych

Zawadzki Jarosław

Systemy Wspomagania w Inżynierii Produkcji

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2020

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Vol.9, iss. 2

182--193

PL

W artykule w przystępny sposób przedstawiono wybrane zagadnienia związane z metodą krigingu zwyczajnego, szeroko wykorzystywaną do estymacji zasobów górniczych. W szczególności opisano te jej właściwości, które choć zazwyczaj mniej znane to decydują o przydatności tej metody i umożliwiają kontrolę dokładności uzyskanych wyników. Szczególną uwagę poświęcono zastosowaniom roli wariancji krigingu, będącej miarą dokładności wyników otrzymanych za pomocą metody krigingu, oraz możliwości jej zastosowania do planowania sieci pomiarowych.

EN

The article presents, in an approachable way, selected issues related to the method of the ordinary kriging, which is widely used for the estimation of mining resources. In particular, such properties of the ordinary kriging were described, which are usually less known but determine its usefulness and accuracy. Particular attention was paid to the role of kriging variance, which is a measure of the accuracy of results obtained using the ordinary kriging. The possibility of using the kriging variance for planning measurement networks was also discussed.

18

A new geostatistical tool for the analysis of the geographical variability of the indoor radon activity

Loffredo Filomena, Scala Antonio, Adinolfi Guido Maria, Savino Federica, Quarto Maria

Nukleonika

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2020

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Vol. 65, No. 2

99--104

EN

The population is continuously exposed to a background level of ionizing radiation due to the natural radioactivity and, in particular, with radon (222Rn). Radon gas has been classified as the second leading cause of lung cancer after tobacco smoke [1]. In the confined environment, radon concentration can reach harmful level and vary accordingly to many factors. Since the primary source of radon in dwellings is the subsurface, the risk assessment and reduction cannot disregard the identification of the local geology and the environmental predisposing factors. In this article, we propose a new methodology, based on the computation of the Gini coefficients at different spatial scales, to estimate the spatial correlation and the geographical variability of radon concentrations. This variability can be interpreted as a signature of the different subsurface geological conditions. The Gini coefficient computation is a statistical tool widely used to determine the degree of inhomogeneity of different kinds of distributions. We generated several simulated radon distributions, and the proposed tool has been validated by comparing the variograms based on the semi-variance computation with those ones based on the Gini coefficient. The Gini coefficient variogram is shown to be a good estimator of the inhomogeneity degree of radon concentration. Indeed, it allows to better constrain the critical distance below which the radon geological source can be considered as uniform at least for the investigated length scales of variability; it also better discriminates the fluctuations due to the environmental predisposing factors from those ones due to the random spatially uncorrelated noise.

19

Geostatistical Methods as a Tool Supporting Revitalization of Industrially Degraded and Post-Mining Areas

Zawadzki Jarosław, Fabijańczyk Piotr, Przeździecki Karol

New Trends in Production Engineering

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2020

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Vol. 3, Iss. 1

30--40

EN

Post-industrial and post-mining areas have often been under strong anthropogenic pressure for a long time. As a result, such areas, after the ending of industrial activity require taking steps to revitalize them. It may cover many elements of the natural or urban environment, such as water, soil, vegetated areas, urban development etc. To carry out revitalization, it is necessary to determine the initial state of such areas, often using selected chemical, geophysical or ecological. After that it is also important to properly monitor the state of such areas to assess the progress of the revitalization process. For this purpose a variety of change detection technics were developed. Post-industrial areas are very often characterized by a large extent, are difficult to access, have complicated land cover. For this reason, it is particularly important to choose appropriate methods to assess the degree of pollution of such areas. Such methods should be as economical as possible and time-effective. A very desirable feature of such methods is that they should allow a quick assessment of the entire area. Geostatistics supplemented by modern remote sensing can be effective for this purpose. Nowadays, using remote sensing, it is possible to gather information simultaneously from the entire, even vast area, with high spatial, spectral and temporal resolution. Geostatistics in turn provides many tools that are able to enable rapid analysis and inference based on even very complicated often scarce spatial data sets obtained from ground measurement and satellite observations. The goal of the article was to present selected results obtained using geostatistical methods also related to remote sensing, which may be helpful for decision makers in revitalizing post-industrial and post-mining areas. The results described in this paper were based mostly on the previous studies, carried out by authors.

20

Geostatistics and Spatial Analysis of Groundwater Hydrochemistry near Leliefontein in the Northern Cape, South Africa

Cudjoe Adadzi Patrick

Journal of Ecological Engineering

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2020

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Vol. 21, nr 8

243--260

EN

The fractured groundwater aquifers, predominantly found in South Africa, show varying groundwater chemical characteristics in various locations. The hydrochemistry of groundwater is affected by the weathering of rock formations in contact and anthropogenic activities. Determination of groundwater chemistry is important for aquifer protection and overall groundwater management. A hydrochemical analysis is a useful tool for identification of water types, chemical composition, its suitability for specified purposes, and an important requirement for water use licensing applications. The hydrochemical data of groundwater from 79 boreholes near Leliefontein, Kamiesberg local municipality of South Africa, were analysed, using integrated statistical, geostatistics and spatial interpolation methods. The result shows Na+ and Cl− to be the abundant cation and anion. The mean concentration of Na at Leliefontein was 267.39 mg/l, and that of Cl was 574.81 mg/l. The ionic concentrations in groundwater was in sequence of Cl− > Na+ > HCO3− > SO42− > Ca2+ > Mg2+ > NO3− > Si > K+ > F-. The analysis indicated that the cation exchanges in groundwater are influenced by limited silicate weathering, with calcite and dolomite dissolution. Geostatistical and spatial analysis interpolation for the major cation (Na) and major anion (Cl), Sodium Adsorption Ratio (SAR), Electrical Conductivity (EC) and Water Quality Index (WQI) was performed using Inverse Distance Weighing method. The hydrochemical data for the Leliefontein groundwater were analysed to classify water for domestic use (drinking) and agriculture (irrigation) purposes, based on the recommended guidelines of the South African National Standard (SANS). The study area was characterised by high salinity of three water types, viz, Na-Cl seawater type, Ca-Cl reverse ion-exchange water type, and Na-HCO3 base ion-exchange water types. About 70–80% of the boreholes in Leliefontein met the requirement for irrigation application for Sodium Adsorption Ratio (SAR) and salinity hazard analysis, while the groundwater generally required further treatment before domestic use.