Abstract

The study was conducted at two sites in Sondu-Miriu basin between November 2010 and May 2011, using runoff plots to determine the temporal variation of sediments, organic matter, solids and surface runoff from agricultural land uses. At Kabianga, lower sediment and surface runoff values were observed in natural vegetation while runoff was generally higher in April-May 2011 wet season. While there were significantly lower sediment concentrations and higher runoff volumes, organic content was significantly lower in April-May 2011. Principal Components Analysis correlated surface runoff and erosion to seasonal land use activities particularly during wet seasons depicting the influence of hydrology on surface runoff pollution. In Sondu, sediment concentrations were lower in natural vegetation. Surface runoff was higher in January-March 2011 in natural vegetation but lowest in cropped systems during April-May, 2011. Solids and organic matter were significantly higher in November-December 2011 (p<0.05). PCA linked surface runoff quality to changes in hydrological periods which influenced the nature, quality and quantity of material transported via surface runoff. PCA for River Sondu-Miriu at Kabianga suggested ionic pollution by dissolved substances (r = 0.77-0.99, p<0.01) and sediment load introduced via surface runoff during wet seasons. In Sondu, PCA associated ionic pollutants and sediment loads to hydrological changes relating to seasonality (r = -0.75-0.99, p<0.01). Temporal variations in surface runoff volumes, water quality and sediment load correlated significantly to hydroperiods in Sondu-Miriu basin. Hydrological changes impacted highly in agricultural land uses with reduced land cover which increased surface runoff accompanied by higher sediment loads.

Keywords:

Hydrology, pollutants, principal component analysis, seasonality,

References

Competing interests

The authors have no competing interests.

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The authors have no competing interests.