Integrated Approach Using Remote Sensing and Gis Techniques for Delineation of Groundwater Potential Zones in Dire Dawa Rivers Catchment, Eastern Ethiopia.
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Date
2013-06-06
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Addis Ababa University
Abstract
Groundwater is one of the very precious natural resource of earth that sustains all human
activities. It is essential not only for sustenance of the human life but also for the
economic and social progress of a region. Integration of remote sensing data and the
geographical information system (GIS) for the exploration of groundwater resources has
become a advance in the field of groundwater research, which assists in assessing,
monitoring, and conserving groundwater resources. Present paper is an attempt to
delineate groundwater potential zone in Dire dawa rivers catchment, eastern Ethiopia
using integrated approach of remote sensing and GIS techniques. The Ethiopia geological
survey of NC 37-12 and NC 38-9 Geological map, Landsat (2011), SRTM, FAO soil
data and Meteorological data are used to prepare various thematic layers such as
lithology, slope, land-use, lineament, drainage, soil, rainfall, geomorphology and water
level depth maps. They were transformed to raster data using feature to raster converter
tool in ArcGIS and again to IDRISI raster for weight calculation. Digital image
processing of Landsat ETM+ was carryout and interpreted to produce thematic map of
land use/cover in ERDAS Imagine. Lithology and lineaments for lineament density were
digitized from geological map. Contours for elevation, drainage lines for drainage
density, slope and geomorphology were prepared from SRTM and soil map from FAO
(the Digital Soil and Terrain Database). The rainfall map and depth to water level are
interpolated from point data. Multi-criteria evaluation technique is used to integrate all
the thematic layers. Individual themes and their corresponding categories are assigned a
knowledge base ranking depending on their suitability to hold groundwater and their
weights are calculated. Using weighed overly analysis in Arc GIS software; all thematic
maps are integrated to produce a composite groundwater potential map of the study area.
This map was further classified into five categories which represents Very poor to Very
potential zones. The result indicated that large part of the study area is classified under
good category and the groundwater potential of the study area is related mainly to
geology, geomorphology, slope and lineaments. Spatially the very good and good
categories are distributed along plain geomorphic units, near to lineaments, less dense
drainage density and where the lithology is affected by secondary structure and having
interconnected pore spaces. The validity of the model was checked against borehole, dug
well, spring data distribution and bore hole yield which reflects the actual groundwater
potential of the area; where out of 90 borehole data collected, 81 are on very good and
good zones, 9 on moderate zones. From all of 27 dug wells and 23 springs covering the
entire catchment area, 22 and 11 of them are located in very good and good groundwater
potential zone and the other 5 and 12 are in the moderate and poor zone respectively.
Moreover out of 47 bore holes with yield between 0.4-10l/s, 41 bore holes are on the very
good and good zones and 3 on moderate zone; out of 14 bore holes with yield between
10-20l/s all of them are in very good and good zone and from 18 bore holes with yield
between 20-60l/s 13 are in very good and good zone. Even though, dug wells exist in all
groundwater potential zones, the best yielding wells lie in the very good and good
groundwater prospect zone.
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Keywords
Groundwater Potential, Geographic Information System, Remote Sensing, Multi Criteria, Decision Evaluation, Weight, Dire Dawa, Eastern Ethiopia