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- Asssessing ground water quality of Addis Ababa city by using Geographical Information System
- GIS Applied to the Hydrogeologic Characterization – Examples for Mancha Oriental Aquifer (SE Spain)
- GIS Applied to the Hydrogeologic Characterization – Examples for Mancha Oriental Aquifer (SE Spain)
- Assessment of groundwater contamination using geographic information systems

All Rights Reserved. The quality of ground water in Juja Location is of great significance because it is the main alternative source of drinking, domestic and industrial water supply. The study aimed at mapping the potential of ground water in the Location, assess the quality of ground water and relate it to the land use and land cover.

## Asssessing ground water quality of Addis Ababa city by using Geographical Information System

Application of Geographic Information Systems. The population on planet Earth, according to FAO forecasts,will increase from 6 billion to 8. Fresh water has ceased to be an inexhaustible resource to become a rather limited and scarce one. Earth's hydrosphere has an approximate volume of 1.

This volume of water is distributed into four groups:. The remainder of water on Earth 0. Ocean water is salt water and the glaciers are difficult to utilize because they are located far from major populated areas. Therefore, we find that groundwater is the largest volume of freshwater available to man. The volume of groundwater is 4, times greater than that of rivers and 30 times higher than the rest of liquid water that is on the surface of the continents.

In addition, groundwater has characteristics that make it especially attractive to combating the processes of drought and desertification. Groundwater is held in a naturally occurring reservoir called an aquifer, a geologic formation capable of storing, receiving and transmitting water so that man can easily take advantage of economically significant quantities to meet needs.

The water is contained in any geological formation ie: river gravel, karstified limestone, porous sandstone and so on. Like all scarce resources, groundwater management must be approached from a dual approach Knowledge and Sustainability :. Knowledge : There must be a sound understanding of the hydrogeological aquifer system to be managed. This should include a detailed analysis of the hydraulic aspects geology, hydraulic parameters and groundwater flow and should be contrasted with the hydrochemical aspects of water containing origin of the substances dissolved in groundwater and hydro-chemical changes due to movement through groundwater flow.

If users pump a volume of groundwater for short-term needs ie: drought conditions , beyond the resources available, they use the aquifer reserves. Then, the aquifer must be given time to recover either by saving water or allowing recharge to increase during periods of more rainfall. Otherwiseresources suffer overexploitation, putting the aquifer at risk of becoming depleted.

It is obvious that the water volumes involved should be determined as precisely as possible. In managing groundwater resources, Geographical Information System GIS are tools capable of storing and managing spatial hydrogeological data by spatial referencing in digital formats.

The correlation of all data with location is the key feature of GIS, which provides the ability to analyze and model hydrologic processes and produce results in maps and in digital formats. Thus, GIS can be considered a support systemin decision making and an ideal tool for monitoring certain hydrogeological processes with socio-economic impacts Goodchild et al.

This scheme is integrated into a a block of hydrogeological data maps of the study area, which supplies data on groundwater from urban and industrial and general hydrological information surface and groundwater hydrology necessary to carry out the integration and interpretation of some results, and b a block of data from remote sensing imagery. Remote sensing allows for classification of crops and their relationship to water supply for irrigation, mapping of wells, and the assessment of recharge by precipitation of rainfall.

All this information is transferred to software that simulates groundwater flow in the Mancha Oriental aquifer using intersection tools. The main goal is to show the methods some GIS applications have in hydrogeological studies. This chapter is divided into two sections which describe some examples of hydrogeological characterization, and secondly, a method for calculating groundwater abstraction.

To demonstrate these applications one of the largest aquifers in southern Europe in terms of area , the Mancha Oriental System has been chosen. Basic diagram of coupling remote sensing and GIS techniques with the groundwater flow model of the Mancha Oriental System. In general, among the Earth Sciences and particularly hydrogeology, sources of data tend to be from points wells, points of water, lithological columns, etc.

This type of data, usually measured in the field, must be spatially distributed in a continuous manner such that a value is given for any point within the space. To achieve this, interpolation or spatial estimation is used.

This method derives an interpolation function that provides estimates for a point in space based on the points measured. GIS tools have incorporated algorithms which perform these operations with discrete entities vector and generate spatially continuous entities raster, line models, etc. The most commonly used spatially continuous entities are raster maps, which are characterized by a two-dimensional numerical matrix or digital image. Each element of the matrix, called a picture element or pixel, has an attribute assigned to it in the database.

The only requirements are for maps to have attribute values referenced to the same coordinate system and the same number and arrangement of pixels to perform algebra operations with them ie: isopaches: difference between top and the bottomraster maps of the geologic formation; calculation of storage volumes: difference between raster maps and contour lines or groundwater for different dates, multiplied by the storage coefficient, etc.

An interpolation function must be obtained:. This type of method is characterized by associating a mathematical function, such as an interpolation function, to the measured or observed values, in which these points are considered without error.

Following the nomenclature followed until now, this mathematical function could be written in the following manner:.

For example, in a simple exact interpolation the observed or measured values Zi coincide with the Cs values, multiplied by a weighting factor given by the function f x i. The deterministic interpolation functions differ from one another in the means of evaluating f x i and Ci. There are various deterministic interpolation techniques. This method assigns the value of each measured or observed point to each pixel or node of the interpolated area. For each point of observation the Euclidean distance is calculated for all other points and each is given the closest value.

The result is a map of polygons with an interpolated value Fig. The estimation or interpolation in this type of method is performed by a weighted average of the observed values. At each point of observation a weight is assigned. The selection criterion is that the weighting function is exclusively dependent upon the distance d. The weight will decrease with increasing distance between points.

The most common strategy for generating this criterion is the Inverse of Distance raised to some exponent a. At times the number of points of influence is restricted, or a radius or maximum distance is assigned for considering points of observation. In this method the interpolating function is a polynomial function which varies in its exponential order. The choices for polynomial are: a through exact fit and b fit by least mean square. The first method aims to resolve the system of equations defined by the n points of observation.

If there are many points of observation, the fit of higher order polynomials can become unviable, giving unrealistic interpolations with exaggerated variation among the values Fig.

In fact, by default these methods limit the polynomial to third order and only use the number of points in a nearby group. One special case of polynomial interpolation is linear interpolation, wherein the interpolation function is a first order polynomial which directly depends on the position of the observed values.

It is an exact method and does not take into account the spatial distribution of the variable, with the result of soft surfaces.

It is an easy method and is often used, above all in cases when not a lot of data is available and the aim is to study the spatial variation of a certain variable. In general, this interpolation method is not used for spatial estimates on realistic structures topography, groundwater levels, etc.

Within polynomial interpolation, this general method generates a different series of expressions for each subdomain into which the whole interpolation space has been divided, wherein continuity requisites are imposed, especially in the contours common to more than one subdomain. The results of this interpolation tend to be surfaces with small changes in levels Fig.

This methodology is based on the premise that the variable to be interpolated is a random function associated with probabilistic distribution laws. This type of method gives a. Examples of the different deterministic interpolation methods using GIS tools. A Polygons of Influence Thyessen polygons, Nearest neighbor , B Interpolations based on weighting functions in this case the function is the inverse distance squared IDW ; C polynomial interpolation, in this case third order; D Spline functions.

The same data are used for each case and the results are shown as continuous identical spatial entities,with the same size and pixel size. The most common method, Krigging, which is available in most GIS software packages, is explained below. Krigging was created under a new discipline, geostatistics, as a resultof problems presented by deterministic interpolation in Earth sciences due to the uncertainty and variability of data Cassiraga, The starting hypothesis of geostatistics is that the data of study has a correlation spatial structure, as the realization of an infinite amount of possible realizations.

For this reason, geostatistics is called the science of regionalized variables. For spatial estimation using Krigging, the steps below should be followed, among others, and the variable to be interpolated should meet the criteria of normality and stationarity Johnston et al.

The first step is structural analysis, with the objective of estimating the semivariogram. First, the variable should be defined as stationary, if there is a tendency among the data, etc. The function of the semivariogram estimator of spatial variability is expressed as:.

At first, from the observed data an experimental semivariogram will appear. A theoretical function with similar behaviourcan be fit to this in order to calculate a weighting matrix for each point, and statistical error affecting the interpolation can be calculated. The semivariogram is composed of a series of elements Fig. The experimental variogram cannot be used for the geostatistical application.

It must be fit to a theoretic model Fig. There are different technical variogram models available, with the most popular being the stationary or spherical semivariogram. Once the theoretical semivariogram has been chosen, the Krigging technique performs the spatial estimation of the data.

There are diverse Krigging techniques as a function of diverse methodological hypotheses:. Residual: Non-stationary hypothesis with a known drift, from which residuals are derived and ordinary Krigging can be performed,. The area has a semiarid Mediterranean climate.

The impermeable base and southwest boundary of the area of study is composed of marl, clay and gypsum from the Lower Jurassic, belonging to HU8 Fig. Over the last 30 years the progressive transformation of approximately , ha from dry to irrigated farmland has translated into an acceleration of socioeconomic development due to widespread use of groundwater resources.

In this context, the MOS is an ideal case study for testing and validating the usefulness of GIS Techniques for understanding the aquifer system and planning for sustainable management. Following is a description of the interpolation methods applied to these variables: a The elevations of the top and bottom of the aquifer units, b Hydraulic parameters, c Groundwater level data d Groundwater chemistry.

The approach is to explore the variable data with histograms and spatial trend analysis in orderto understand the behaviourof the variable in space as well as to establishwhether the data are consistent or anomalous. After analyzing the data, a variable is selected to be interpolated. The type of interpolation to apply for raster maps or continuous spatial entities is chosen. Simplified hydrogeological map of the MOS. Taken from Sanz et al.

Graphical output from GIS software. Any attempt at making a coherenthydrogeological model should be approached by first understanding, with a certain amount of precision, the geometric configuration. Using this information, layers of geographically located points X, Y coordinates as well as the topographic height of the superior top and inferior bottom limits were made into attributes of each hydrogeologic unit that behaves as an aquifer.

Using geostatistical interpolation models developed on theoretic and applied foundations, GIS software i.

## GIS Applied to the Hydrogeologic Characterization – Examples for Mancha Oriental Aquifer (SE Spain)

Show full item record. JavaScript is disabled for your browser. Some features of this site may not work without it. Date: Abstract: Groundwater is one of the most important natural resources.

## GIS Applied to the Hydrogeologic Characterization – Examples for Mancha Oriental Aquifer (SE Spain)

Groundwater quality assessment is vital to protect this resource. Therefore, the aims of this study were to evaluate the hydro-chemical quality of the Marvdasht aquifer located in the semi-arid region of Iran and to map the groundwater quality parameters. For this purpose, a mean data of 11 groundwater quality parameters collected from 49 wells — were used.

Application of Geographic Information Systems. The population on planet Earth, according to FAO forecasts,will increase from 6 billion to 8. Fresh water has ceased to be an inexhaustible resource to become a rather limited and scarce one. Earth's hydrosphere has an approximate volume of 1. This volume of water is distributed into four groups:.

E ; moc. The observation of groundwater quality elements is essential for understanding the classification and distribution of drinking water. Geographic Information System GIS and remote sensing RS , are intensive tools for the performance and analysis of spatial datum associated with groundwater sources control. In this study, groundwater quality parameters were observed in three different aquifers including: sandstone, alluvium and basalt.

### Assessment of groundwater contamination using geographic information systems

Spatial variations in ground water quality in the corporation area of Gulbarga City located in the northern part of Karnataka State, India, have been studied using geographic information system GIS technique. GIS, a tool which is used for storing, analyzing and displaying spatial data is also used for investigating ground water quality information. For this study, water samples were collected from 76 of the bore wells and open wells representing the entire corporation area. The results obtained in this study and the spatial database established in GIS will be helpful for monitoring and managing ground water pollution in the study area. Mapping was coded for potable zones, in the absence of better alternate source and non-potable zones in the study area, in terms of water quality.

In this study two sites were selected in order to investigate groundwater contamination and spatial relationships among groundwater quality, topography, geology, landuse and pollution sources. One site is the Asan area, an agricultural district where pollution sources are scattered and which is mainly underlain by granite of Cretaceous age. The other site is the Gurogu area of Seoul city, an industrial district where an industrial complex and residential areas are located and which is mainly underlain by gneiss of Precambrian age. Groundwater samples collected from these districts were analysed for chemical constituents. An attribute value files of chemical constituents of groundwater and the spatial data layers were constructed and pollution properties were investigated to establish out spatial relationships between the groundwater constituents and pollution sources using geographic information systems GIS. Pollution over the critical level of the Korean drinking water standard has been investigated from 15 sampling sites out of 40 in the Asan area, and 33 sampling sites out of 51 in the Gurogu area.

- Как твои дела. - Не жалуюсь. Джабба вытер губы. - Ты на месте. - А-га. - Не хочешь составить мне компанию.

Assessing Ground Water Quality using GIS Download full-text PDF for analyzing and mapping water quality and assesses their vulnerability to have been studied using geographic information system (GIS) technique.

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Я сам позвоню этому… - Не беспокойтесь, - прошептала Сьюзан. - Танкадо мертв. Все замерли в изумлении. Возможные последствия полученного известия словно пулей пронзили Джаббу. Казалось, тучный шеф отдела обеспечения системной безопасности вот-вот рухнет на пол. - Мертв. Но это значит… значит… что мы не можем… - Это значит, что нужен другой план действий.

Дверь снова приоткрылась на дюйм. В Третьем узле виднелось голубоватое сияние: терминалы по-прежнему работали; они обеспечивали функционирование ТРАНСТЕКСТА, поэтому на них поступало аварийное питание. Сьюзан просунула в щель ногу в туфле Феррагамо и усилила нажим. Дверь подалась. Стратмор сменил положение.

Джабба всплеснул руками. - Ради всего святого. Шифры-убийцы похожи на любые другие - они так же произвольны. Угадать ключи к ним невозможно. Если вы думаете, что можно ввести шестьсот миллионов ключей за сорок пять минут, то пожалуйста. - Ключ находится в Испании, - еле слышно произнесла Сьюзан, и все повернулись к .

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Теперь предстояло принять решение. Бросить все и ехать в аэропорт. Вопрос национальной безопасности.

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Внутренние ошибки программы не являлись единственными причинами сбоя, потому что иногда в действие вступали внешние силы - скачки напряжения, попавшие на платы частички пыли, повреждение проводов. Поскольку за техникой Третьего узла следили самым тщательным образом, она даже не рассматривала такую возможность. Сьюзан встала и быстро подошла к громадному книжному шкафу с техническими руководствами, взяла с полки справочник с прошитым проволочной спиралью корешком и принялась его листать. Она нашла то, что искала, вернулась со справочником к своему терминалу, ввела несколько команд и подождала, пока компьютер проверит список команд, отданных за последние три часа. Сьюзан надеялась обнаружить внешнее воздействие - команду отключения, вызванную сбоем электропитания или дефектным чипом.

О его существовании знали только три процента американцев. - АНБ, - пошутил приятель, - означает Агентство, которого Никогда не Было. Со смешанным чувством тревоги и любопытства Беккер принял приглашение загадочного агентства. Он проехал тридцать семь миль до их штаб-квартиры, раскинувшейся на участке площадью тридцать шесть акров среди лесистых холмов Форт-Мида в штате Мэриленд. После бесчисленных проверок на контрольно-пропускных пунктах он получил шестичасовой гостевой пропуск с голографическим текстом и был препровожден в роскошное помещение, где ему, как было сказано, предстояло вслепую оказать помощь Отделению криптографии - элитарной группе талантливых математиков, именуемых дешифровщиками.

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The study of groundwater quality parameters is most essential for irrigation and drinking water, and its quality is a serious problem around the study area.

tion of groundwater ﬂow are shown in Fig. 3. It was digitized in a Universal Transverse Mer-. cator (UTM) projection system by applying the.