Abstract:
The search for groundwater is vital as an immediate and sustainable solution to the scarcity of
water for drinking and other domestic uses in heavily populated areas like Fango Lome
catchment of Southern Ethiopia. The current study was therefore conducted to assess the
groundwater potential in Fango Lome catchment, found in Humbo district. The study used
two non-destructive geophysical techniques, Electrical Resistivity Tomography (ERT) and
Gravity Methods to assess the aquifer bearing potential structures. A total of 427 gravity
points and six ERT profiles were collected in the current study. SYSCAL Pro Earth
Resistivity Meter was used to obtain the electrical resistivity imaging data and RES2DINV
software was used to process the data. Gravity data were recorded using GPS and analyzed
using Geosoft Oasis Montaj (Version 8.4) interpretation software.
The analysis of the results obtained from the ERT method revealed that the study area is
characterized to have four distinct layers of soil with different texture and apparent resistivity:
The first layer with very low apparent resistivity value was identified to represent silty clay
soil, the second layer has relative low apparent resistivity value is correlated to represent
slightly weathered and fractured basalt materials, the third layer has moderate apparent
resistivity value is characterized by highly fractured and weathered basalt, and the fourth
layer has indicated massive bedrock materials with higher apparent resistivity. The third layer
is expected to be a good source of ground water or aquifer horizons. Similar result was also
found from the Gravity method which was employed to depict the lateral and depth variation
in density. Accordingly, the result revealed that the subsurface geologic structure of the study
area consists of four main density layers: the first density layer associated with silt and clay
soil, the second density layer likely representing slightly weathered and fractured basalt, the
third density layer characterized by highly weathered and fractured basalt - which is expected
to be a good source of ground water or aquifer zone- and the fourth density layer probably
composed of massive base bade rock. The overall discussion was done by integrating all the
above results together with the topographic map, geologic and borehole information. Finally,
based on these results, geological structures and groundwater aquifer potential zones were
identified and drilling sites are recommended
