Studies on the Influences of Landuse on Soil and Water Resources in Thika District, Kenya
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Date
2003
Authors
Karuri, A. W.
Wamicha, W. N.
Maina, D.
Bartilol, S. K.
Journal Title
Journal ISSN
Volume Title
Publisher
Soil Science Society of East Africa
Abstract
In the last three decades a decline has been observed in water and soil resources resulting from
non-point or point source pollution. Landuse patterns may contribute to pollutants flowing into
water or soil within a certain region. This study was carried out to investigate the influence of
different landuse patterns on water and soil quality. Data collection was done from three major
landuse .zones namely coffee, horticultural and Thika urban zone during the period September
1999 to June 2000. Twenty-one water samples were collected per each site along Chania River
and levels of heavy metals were determined using x-ray fluorescence. In addition, twelve
representative soil samples were collected per site along the Chania River and levels of heavy
metals in soils were also determined. Heavy metal levels in water were found to be higher in the
Thika urban site (Blue post) compared to coffee zone site (Egaad Estate) located upstream.
However, the levels are still below the drinking water standards. With increase in the use of
agrochemical inputs and soil erosion the levels of heavy metals in water or soil may increase in
the future.
Soil samples reflected higher levels of heavy metals than water but still within allowed limits.
Statistical analysis further revealed a correlation between land use and heavy metals in river
water as well as from the soil. Iron and zinc were found to be higher compared to other metals.
Chania River receives agrochemical wastes from horticultural and coffee farms as it flows from
Egaad coffee-estate to Bluepost. Therefore the levels of heavy metals at downstream site at Thika
Blue post was found to be higher than levels at upstream site at Egaad coffee estate. For example
zinc in river water was 2.9ppb and 1l.6ppb at Egaad coffee estate and Thika Blue Post
respectively. The allowed limits for zinc in drinking water standards set by Kenya Bureau of
Standards is 5.0Oppm To prevent increase of heavy metals in soil and water, there is need for
proper landuse planning such as reduction of agrochemical inputs especially from the
horticultural farms. Incorporating integrated pesticide control, agricultural extension or
enhancing soil conservation methods such as afforestation would further reduce heavy metal
pollution.
Description
This paper was presented at the 18th conference and end of millennium celebration of the Soil Science of East Africa (SSSEA) on 'Sustainable use of land resources to alleviate poverty in the new millennium' 4th – 8th December, 2000 held at Mombasa, Kenya
Keywords
Chania River, Landuse, Water quality, Heavy metals, Environmental pollution
Citation
18th conference and end of millennium celebration of the Soil Science of East Africa (SSSEA) 4th – 8th December, 2000