Asssessing ground water quality of Addis Ababa city by using Geographical Information System
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Date
2014-06
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Addis Ababa University
Abstract
Groundwater is one of the most important natural resources. It becomes a necessary resource
over the past years due to the increase in its usage for drinking, irrigation and industrial uses
etc. Groundwater quality assessment is necessary to guarantee sustainable safe use of water.
Mapping of spatial variability of groundwater quality is of vital importance and it is particularly
significant where groundwater is primary source of potable water. The present study has been
undertaken to analyze the spatial variability of groundwater quality for Addis Ababa city, capital
of Ethiopia. Ground water pollution is a global issue. However, the extent and degree of severity
of water pollution is more prominent in developing countries. The aim of this research is to
provide an overview of present groundwater quality spatial distribution over the city of Addis
Ababa. Geographical Information System (GIS) is used for the spatial analysis and it is a
powerful tool for representation and analysis of spatial information related to water resources.
Geostatistics was used to determine the spatial distribution of groundwater quality parameters in
the study area using GIS and geostatistical techniques. Ordinary kriging interpolation
techniques was applied to generate water quality maps. The major water quality parameters
such as Total Dissolved Solids, Total hardness, Chloride, Nitrate, Sulphates, Magnesium and
Calcium have been analysed. The spatial variation maps of these groundwater quality
parameters shows that mostly in the central part of the city there is high concentration of nitrate,
TDS, total hardness. But from those parameters chloride, Magnesium, calcium and sulphate
have low concentration below the world health Organization standard. The final integrated map
shows four priority classes such as Excellent, Good, Poor and Very poor groundwater quality
zones of the study area and provides a guideline for the suitability of groundwater for domestic
purposes. Water quality index (WQI) was used to assess the suitability of groundwater from the
study area for drinking purpose. From the WQI assessment The map showed that 78.18 %
(422.17 km2) of the groundwater of the city were found to be in the excellent water class, 20.86
% (112.62 km2) good, 0.9 % (4.87 km2) poor and the remaining 0.06 % (0.34 km2) was classified
under very poor water class based on the computed WQI classification results.
Key words: Geostatistics, GIS , Ground water, Interpolation, water quality
Description
Keywords
Geostatistics, GIS, Ground water, Interpolation, Water Quality