Abstract:
In this case study nutrients and sediment were considered to be an important water
quality concern in Nyangores Catchment in the larger Upper Mara Catchment shown
in figure 1 due to high eutrophication of the river as is evident at some sections of the
river. Nitrogen and Phosphorous originates from inorganic and organic fertilizer that
affect the river water quality due to intensive agricultural farming and livestock
grazing. Increased fertilizer application has enlarged N and P nutrient burden into the
river through runoff leading to pollution and consequently eutrophication.Three plots
of different vegetations were set up to represent different scenarios of riparian
vegetation. Plots representing natural forest, grassland and bare land a distance of
twenty meters apart to avoid disparity , were set up to determine their effectiveness in
controlling the nutrients. The plots each measured 2m by 10m were set up for Natural
forest, bare ground and grassland field. Runoff samples were collected from the plots
on rainy days, and taken to the laboratory for Ph, Ec, NO3 and PO4 analysis. From the
samples analysis the results showed the Ph for the natural forest, bareland and
grassland were 7.0, 6.8, and 6.5 respectively, for the nitrates were natural forest 0.20
mg/l, bareland 0.5 mg/l, grassland 0.3 mg/l for phosphates forest it was 0.01gm/l for
bareland it wasـ
0.57 mg/l and for grassland 0.55 mg/l. For the Electrical conductivity, forest gave 0.4 mhos,
bareland
0.5 mhos and 0.2 mhos for grassland. There is a clear indication that Natural forest on
top of controlling the Ph and Ec better than grassland, it has a natural sink for nitrates
and phosphate. It is therefore recommended that natural forests be reserved and that
grass should be used as an alternative for riparian zones.
Key words: Riparian, Nutrients, Water quality, Water bodies.
