Analysis of Riparian Land Rehabilitation on Water Quality and Macro Invertebrates’ Diversity along Nairobi River, Kenya
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Date
2023
Authors
Ndichu, NN
Tela, SA
Kweyu, RM
Makokha, M
Okeyo, F
Journal Title
Journal ISSN
Volume Title
Publisher
IJWR
Abstract
Aquatic life has been facing a lot of threat from the anthropogenic activities occurring near water bodies. This calls
for rehabilitation actions to save the lives. The aim of this study is to analyze the rehabilitation actions that have
taken place along Nairobi River and how the remedies have affected water quality as well as diversity of macro
invertebrates. Notable rehabilitation activities have taken place at a river section called Michuki Park where garbage
collection, fencing, planting of trees (vegetation), offering security among other practices have been undertaken.
Comparison was done between the rehabilitated and non-rehabilitated sections of the river. The objectives of this
study are: To assess the riparian cover types along Nairobi River, to analyze the relationship between riparian cover
types and water quality, to determine the impact of rehabilitation on water quality and to establish the relationship
between rehabilitation and diversity of macro invertebrates. The land use cover assessed were forest, shrubs, bare
land and settlement (development). These land use cover types were analyzed in order to help in understanding the
human activities carried out along the river. Four main sampling points were used to gather data where in each two
samples were taken. The process was done both in a dry and a wet period. A total of 16 samples were analyzed. Data
collected was analyzed using the satellite image analysis for the period of study. Data presentation was done in maps,
tables, and graphs.
The study findings revealed significant differences in water quality parameters between rehabilitated and nonrehabilitated zones during dry days (P<0.05), but no significant differences on wet days (P>0.05). The number of
macro-invertebrates showed no significant difference. Pearson's correlation analysis revealed a negative relationship
between macro-invertebrate diversity and nitrates and phosphate levels (r=-0.863 and -0.603, P<0.05). Although not
statistically significant, negative relationships were observed between macro-invertebrate diversity and water
temperature, electrical conductivity, total dissolved solids, and turbidity. Dissolved oxygen and pH showed positive
correlations with macro-invertebrate diversity. Species evenness was positively influenced by nitrate levels (r=0.360,
P=0.043). Other factors such as water turbidity, phosphates, and electrical conductivity also had positive
relationships with species evenness. The comparison between the rehabilitated and non-rehabilitated areas showed no
significant difference in macro-invertebrate diversity (t=0.478, P=0.636), but a significant difference in species
evenness (t=2.35, P=0.0255). The rehabilitated area had higher pH and dissolved oxygen levels, while the nonrehabilitated areas had higher electrical conductivity, total dissolved solids, and turbidity. Nitrates and phosphates
were significantly higher in the non-rehabilitated area. Interview responses indicated that 25% of the participants
reported benefiting from Nairobi River water despite its deteriorating quality, while 75% did not report any benefits.
The diversity and abundance of macro-invertebrates were significantly influenced by key parameters. Oxygen
showed a positive correlation, while phosphates and nitrates exhibited a negative correlation with macro-invertebrate
diversity and abundance. The study emphasized the positive impact of rehabilitation on aquatic life, as rehabilitated
areas had higher diversity. To prevent pollution, measures such as proper waste disposal and penalties for polluters
should be enhanced. Further research is recommended to explore the distribution and adaptability of other species in
the river, as well as identify extinct species. Public education on the detrimental effects of pollution on aquatic life is
crucial. Expanding rehabilitation efforts to cover larger sections or the entire river is suggested. The study's findings
raise awareness among residents living along the river about the harm caused to water biodiversity.
Description
Article
Keywords
Riparian, Rehabilitation, Macro Invertebrates, Degradation
Citation
Nyambura Ndichu, N., Abuyeka Tela, S., & Kweyu, R. M. (2023). Analysis Of Riparian Land Rehabilitation on Water Quality and Macro Invertebrates’ Diversity Along Nairobi River, Kenya. International Journal of Water Research, 5(4).