Abstract:
Groundwater is the most valuable natural resource in the world and it is the fundamental source
fresh water, for growth and development of one country. However identifying the groundwater
potential zone is still complex due to the nature of groundwater and their quality also vary due to
spatial variation. Therefore, this study aims to use the timely and cost effective geographical
information system (GIS) and Remote Sensing methods for identifying groundwater potential
zone, assessing the its quality for drinking purpose and examining the connection between them in
Chagni and the surrounding area. For groundwater potential zonation nine thematic layers
derived from Digital Elevation Model (DEM) with 12.5m spatial resolution, sentinel 2A Satellite
image of the year 2021, and other secondary sources were utilized in this research. Using MCDA
of AHP method all of the thematic layers (slope, rainfall, drainage density, lineament density,
geomorphology, lithology, soil, land-use/land-cover and groundwater depth) were reclassified
and weight for each factor was assigned based on their relative contribution to groundwater by
the help of experts’ knowledge. The resulting map of groundwater potential zone were identified
by using weighted linear combination (WLC) in ArcGIS and shows 15.1% and 48% of the area
has very high and high potential respectively, while 2.6 % of the area has very low potential. For
groundwater quality assessment collected water samples from 11 wells were tested in the
laboratory. About 12 water quality parameters (pH, EC, Turbidity, TDS, NO3-N, Nitrate, Total hardness, potassium, Iron, Fluoride, chloride and Sodium-Chloride) were analyzed using Water
Quality Index (WQI) method. The spatial distribution map of all the water quality parameters and
overall WQI map were prepared with IDW interpolation method. The WQI result shows that well
1, 4 and 8 are poor (WQI > 100), well 2, 5, 9 and 11 are good (WQI is 50-100) and well 3, 6, 7
and 10 are excellent (WQI below 50) for drinking purpose. Based on the result around 21.1% and
73% of the study area has excellent and good water quality respectively and only 5.9% of the
area was poor quality. Based on the connection between GWP and GWQ in the study area,
around 20% km2
area of excellent water and 68.6km2
area of good water found in high potential
zone. And only 3.69km2
area of excellent water found in low potential zone of the study area. In
general, the assessment of groundwater potential and quality requires further geotechnical and
hydrological analyses to ensure the suitability with required standards for design and
implementation.
Key Words: groundwater potential, groundwater quality, GIS, AHP, WQ