| dc.description.abstract | The groundwater geochemistry of Butula area of Busia District (which is bounded by longitudes 34°10'
and 34°25' E, and latitudes 01° 15'55" and 0 I°29' I"N and which covers an areal extent of approximately
395 Km2) has been studied.
The study involved determination of the hydrogeochemical and physico-chemical properties, their
occurrence and distribution in the groundwater resources of the study area. TIle area consists mainly of
rocks of the Archean Greenstone belt of Western Kenya especially the metavolcanics of the Nyanzian
Group and the metasediments of Kavirondo Group both of which are intruded by the Mumias granite.
High groundwater potential is found within the Kavirondian sediments and the Mumias granite. Water is
encountered in the wells within this area at depths ranging from 3.5-18.98 m i.e. the water rest levels
(WRLs).
Twenty-eight boreholes, two shallow wells and three rivers were randomly sampled in this study. Each
sample was analysed for the content of Na, K, Ca, Mg, Si, Pb, Zn, Fe, Mn, Cu, S04, CI, F, C03, HC03
and N03 together with other physico-chemical parameters in water such as TDS, total hardness, electrical
conductance, pH, etc. The hydrochemical parameters such as temperature, electrical conductance (EC),
total dissolved solids (TDS), and pH were measured in the field using a HACH CNDffDS & T meter
(model PIN 44600-00) and a JenwayTDfi/T meter (model 4076). An Orion Model 801 specific ion meter
was used for the determination of fluoride and chloride ion levels in water. Metal cations (as mentioned
above) were determined by use of a Chem Tech Analytical Atomic Absorption Spectrometer (AAS)
instrument model CTA-2000. The other anions including of carbonate, bicarbonate (alkalinity) and total
hardness (TH) of water were determined by wet or titrimetric methods. The water resources in the area are
generally slightly acidic and have pH values ranging from 5.9 to 7.2. All the waters analysed in this study
had pH values below 7.8 but above 5.0.
Iron and manganese were found to be in excess of the WHO recommended limits for potable water
quality while fluoride was in relatively low amounts ill the groundwaters of the study area. The chemical
data obtained from this study have been subjected to statistical analysis. Correlation coefficients together
with factor analysis have been used in order to understand and characterize the groundwater behaviour.
Trilinear (Piper) diagrams, concentration maps and' statistical (correlation coefficient) analysis were also
used in the synthesis of the data so as to' establis11 both quantitatively and qualitatively the physicochemical
aspects of groundwater quality in this area. A plot of the concentrations of the major constituents
on the Piper (trilinear) diagrams has revealed that the groundwater of this area may be termed as sodium bicarbonate
waters. Statistical analyses of the results using PCA and factor analysis revealed that Ca, CI,
conductivity, F and Fe are the major principal components that determine the groundwater chemistry in this
area. | en |
