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European Journal of Applied Sciences – Vol. 10, No. 5

Publication Date: October 25, 2022

DOI:10.14738/aivp.105.13156. Ogendi, G. M. (2022). Effects of Anthropogenic Activities on the Water Quality of River Nyakomisaro-Riana, Kisii, Kenya. European

Journal of Applied Sciences, 10(5). 171-190.

Services for Science and Education – United Kingdom

Effects of Anthropogenic Activities on the Water Quality of River

Nyakomisaro-Riana, Kisii, Kenya

George Mokua Ogendi

Deparment of Environment, Natural Resource

Management and Aquatic Sciences, Kisii University, Kisii, Kenya

ORCID: https://orcid.org/0000-0002-5133-4989

ABSTRACT

Access to safe drinking water is a major challenge to urban populations in

developing countries. Most of Kisii town residents draw raw water from rivers and

springs for domestic use which is highly contaminated. No water quality

assessments in these rivers have been conducted. An assessment was therefore

conducted on water quality of River Nyakomisaro-Riana flowing through Kisii town,

during May 2013 to October 2014. The overall objective was to to assess the spatial

and temporal variation of selected physical, chemical and biological parameters of

river Nyakomisaro-Riana. Five sampling sites equidistant from one another were

selected to establish a sampling transect for this river. Standard methods described

in APHA, 1998 were used to determine levels of physico-chemical parameters,

nutrient concentrations and biological characteristics. This study was conducted on

this river for the first time and forms a basis for comparison with future studies.

Spatial and temporal patterns of the parameters were analyzed and presented in

tabular and graphical formats using Excel and Sigma Plot software. Descriptive

statistics were done. Analysis of variance and Tukey’s pairwise comparisons were

used to establish whether there were significant differences in studied parameters.

Results indicated that the concentrations of total dissolved solids, Total

supsennded soilds, Electrical conductivity, temperature, total suspended solids

increased downstream while dissolved oxygen concentration and pH decreased.

The increasing trend of the physico-chemical parameters downstream was

attributed to observable anthropogenic inputs via raw sewage disposal into this

rivers, car wash sites, garbage dumpsites close to riverbanks and surface run-off

from the town catchment. Inflow of pollutants into the river was made worse by

unplanned settlements along the riverbank with lots waste disposal facilities, car- wash bays and garages along it. This study recommends that oversight

organizations like NEMA, GWASCO, Ministry of Environment and other related

organizations take necessary action to improve the water quality of this river.

Key words: Physico-chemical, Nyakomisaro-Riana, Anthropogenic activities and Garbage

dumpsites

INTRODUCTION

Safe drinking water has become an increasing concern to man and his animals in the recent

years. Globally, an estimated 1.3 billion people live in low-income countries with little access to

safe drinking water and 2.5 billion people have no adequate sanitation facilities [1] . Therefore,

freshwater resources are dwindling and becoming costly and more polluted as the world

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European Journal of Applied Sciences (EJAS) Vol. 10, Issue 5, October-2022

Services for Science and Education – United Kingdom

population increases [2, 3]. Kenya is among the countries which have not achieved their

Sustainable Development Goal (SDG) of providing safe drinking water to its citizens[4].

Freshwater constitutes 2.5% of the total volume of water in the earth’s surface of which 2.0%

is frozen in the Polar Regions and high mountain peaks, therefore leaving only 0.5% in rivers,

reservoirs and lakes for use. Further, the 0.5% left is subjected to lots of pollution from the

increased anthropogenic activities by the ever-expanding human population and unsustainable

ways of its usage [5, 6, 7]. Clean water has therefore, become a scarce and expensive resource due

to competing demands from the domestic, agricultural and industrial sectors. Because of this,

there is need to conserve and manage the scarce freshwater resource sustainably so that it can

continue to support live on earth.

An estimated 40 % of the world’s population is projected to live in water scarce regions by 2025

[8]. The steep increase in population, urbanisation, consumption and the desire for better living

has placed a greater strain on fresh drinking water supply more especially in urban centres.

For example, the shortage of water in Kisii town has placed a large burden on the women and

children who spend up to one-third of their day fetching water in the hill country side from the

nearest fresh water sources [9, 10]. Due to the expanding urban populations, water quality and

sanitation need to receive specific attention for effective management. Therefore, more

research on water quality need to be carried out to protect public health and highlight the

interventions to be directed at sources of pollution.

Most Kenyan towns for example, Nairobi, Kisii, Narok, Migori and Mumias are either situated

on water towers or on the main rivers flowing into major water systems. They contribute major

sources of organic and inorganic pollutants that pollute these river systems. Due to unplanned

settlements, haphazard placement of pit latrines, inadequate supply of piped water, and poor

sanitation in urban centres, microbial contamination of water is of major concern to consumers,

water suppliers and public health authorities due to the ability of water to transmit pathogens

to a great number of people [11]. This therefore, requires the assessment of activities affecting

the quantity and quality of drinking water supplies to residents in major urban centres. As in

most urban centres of low income countries, the majority of residents in Kisii municipality draw

their water from the rivers nearby or flowing through it.

The study focused on the assessment of the water quality during the sampling period of May

2013 to October 2014. The data collected covered the measurement of selected physical and

chemical parameters, namely:- Dissolved Oxygen (DO), Electrical Conductivity (EC),

Temperature, pH, Total Suspended Solids (TSS) and Total Dissolved Solids (TDS). These

parameters constitute part of major indicators and important tools in water quality assessment,

planning and management. For example, temperature plays an important role in the control of

DO, pH levels and chemical processes going on in the water column. Microbial decomposition

processes utilizing oxygen increase at high temperatures leading to release of simpler

substances and in special conditions release of toxic chemical ions such as ferric III. Several

processes that affect DO concentrations in surface waters include decomposing organic matter,

algal photosynthesis and respiration by both aquatic animals and plants[12].

This study assumed a steady state of environmental conditions in River Nyakomisaro

throughout the sampling period. It also assumed that the inter-annual variation of the physical,

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Ogendi, G. M. (2022). Effects of Anthropogenic Activities on the Water Quality of River Nyakomisaro-Riana, Kisii, Kenya. European Journal of Applied

Sciences, 10(5). 171-190.

URL: http://dx.doi.org/10.14738/aivp.105.13156

chemical and biological parameters remained constant. This study therefore, assessed the

water quality of the Nyakomisaro River which is flowing through the town and provide

information which will be useful in its management.

MATERIALS AND METHODS

Study Area and Sampling Sites

The study area constituted River Nyakomisaro-Riana which is flowing through Kisii Town. The

town is located at an altitude of 1850 meters above sea level and stretches from longitude

34o45’0”E to 34o47’0”E and latitude 0o40’0”S to 0o42’0”S in South Western Kenya (Figure 1). It

is situated approximately 300 km South West of Nairobi on the main highway to Tanzania. It

has a highland equatorial climate, with an average rainfall of 2000 mm yr-1.

Kisii town has annual average high temperatures of 30.4oC and average low temperatures of

10.1oC. The town has one of the highest population densities in the world which stands at 1100

people per square kilometre. The main sources of water used in town are piped water from

River Kuja, nearby rivers like Nyakomisaro, boreholes and the protected and unprotected

springs. The larger volume of the water used by the residents come from surrounding rivers

and boreholes. Less than 20% of the town population is connected to sewerage and piped

water.

Figure 1. Study area Map and its Sampling Sites

(NK1: near source, NK2 , NK3 and R1 sampling points along the transect and midstream and R2:

last sampling point downstream) Source: Sketch from the larger Kisii lands office map (NK

stands for Nyakomisaro, R stands for Riana)