Effects of Riparian Cover Types on Water Quality and Macroinvertebrate Population in River Isiukhu Watershed, Kakamega County, Kenya.
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Date
2023-06
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Kenyatta University
Abstract
Quality riparian cover improves the ecologically health of rivers. Conservation of
riparian buffer zones improves sustainability of rivers in supporting biotic diversity.
However, anthropogenic activities are endangering current and future existence of
riparian cover .The study sought to establish the effects of riparian cover types on
water quality and macro invertebrate population in the Isiukhu River watershed.
Specific objectives that were explored included; to identify the riparian cover types
along the river; to establish the relationship between riparian cover types and water
quality; and finally to establish relationship between riparian cover types and macro
invertebrates diversity, evenness, richness and abundance .Four stations under
different riparian covers were assessed four times for water samples and macro
invertebrates’ specimens in order to achieve these objectives. Riparian cover types that
existed along the river were identified using sentinel (2) image and they include, forest
vegetation, riparian grassland, farmland zone and town zone. Ground photographs
documentation, transect walk orientation and ground truth observations helped in
rating and classifying riparian covers as being very high, high, moderate and low in
relation to riparian cover characteristics. Macro invertebrates were collected using D frame net, identified and classified using relevant classification keys. Shannon-Wiener
index, Shannon evenness index, Species richness and abundance indices are
descriptive statistics that analysed for species population structure. Sorenson’s
Coefficient was applied to quantify similarities or dissimilarities among species in
different stations. Pearson correlation coefficient hypothetically tested significance
correlation between sampling stations and species indices. Water quality parameters
were expressed using mean. Two way ANOVA test revealed that significant variation
existed between water parameters (pH, EC, TDS, DO, Temperature and Turbidity) and
sampling stations (ρ <0.05) and sampling dates (ρ <0.05).1,552 macro invertebrate
species were collected .11 species were positively correlated with riparian covers
,while 3 were negatively correlated with riparian cover. Forest vegetation had highest
species richness (24), Grassland (22), Farmland (19) and Town zone (17) respectively.
Forest vegetation had highest species abundance (377), Grassland (376), Farmland
(387) and Town zone (412). Forest vegetation was more diverse (3.090), followed by
Grassland (2.962), Farmland (2.675) and Town zone (2.493). A close relationship
existed between riparian covers and: macro invertebrates’ diversity (r =0.9904; ρ
=0.08333); richness (r =0.9965; ρ =0.08333); evenness (r =0.9809; ρ =0.08333); and
abundance (r = -0.8939; ρ =0.3333). Chiromonous sp. and Tubifex sp. dominated
downstream stations while Belostoma sp., Heptagenia sp. and Caenis sp. dominated
upstream stations. The study established that river Isiukhu ecosystem is adversely
affected by dynamics which are simplifying the riparian cover along the river.
Therefore, application of holistic approach in river health assessment is recommended
through assessing physical, biological and chemical aspects of the ecosystem .This
will lead to better understanding of ecosystem processes, thus leading to effective
management and conservation of riparian resources.
Description
A Thesis Submitted in Partial Fulfilment of the Requirements for the Award of the Degree of Masters of Arts in Geography (Biogeography) in the School of Humanities and Social Sciences of Kenyatta University, June, 2023