Evaluation of irrigation water quality of the Yatta canal in Machakos county, Kenya
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Date
2014-10-31
Authors
Mang'oka, Joseph Muli
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
The Yatta. Canal in Machakos County is a major water resource used by the local
community for domestic and small-scale irrigation. The water quality has however
degraded over the years due to sequential use and re-use since it's the only single source
of water supply. There has been no study conducted to test the quality of this water which
acts as a lifeline to the Yatta residents. This study therefore aims to evaluate the irrigation
water quality of the Yatta canal in Machakos County, Kenya. The specific objectives are;
To analyze the physico-chemical properties of the canal water used for irrigation; To
determine the biological composition of the canal water and to compare the levels of
contamination with agricultural practices along the canal. The research design is
experimental involving laboratory analysis of physico-chemical and biological properties
of canal water. For the purpose of this study, twenty water samples (S 1, S2, S3 .... S20)
will be collected during the dry and wet seasons between 8am and lOam using a longhandled
plastic scoop and stored in cleaned polyethylene bottles without any air bubbles.
Water samples will be collected at lkrn intervals along the canal from the main intake of
Thika River and preserved according to APHA, 1985. Systematic grid sampling method
will be used to identify sample collection points and within mid depth of the canal. The
grid and initial sampling points will be randomly selected. At each sampling location,
field measurements of unstable water parameters such as colour, odour, temperature, pH,
dissolved oxygen, total dissolved solids and turbidity will be performed prior to sample
collection. Later on, samples for laboratory analysis will be collected and transported at
temperatures of 4°C for laboratory analysis within 24 hours of collection. Data obtained
from the canal water analysis will be analyzed using statistical package for the social
sciences, tabulated and presented through descriptive and inferential analysis. Analysis of
Variance test will be used to determine the level of variation between the concentration of
physico-chemical and biological properties of the canal water during the dry and wet
seasons as well as current agricultural practices within the various sampling points. The
results will be compared with National Environment Management Authority, World
Health Organization as well as Food and Agriculture Organization and recommendations
made to policy makers and stakeholders