Rivers are essential ecosystems that assist in maintaining and supporting functions and ecological processes that are important for sustaining the biodiversity and providing services and resources to people. However, in the tropics they are under threat of deterioration as a result of human encroachment and more so, removal of riparian vegetation. This study aimed at assessing the effects clear-cut of Tumoo forest on water quality, coarse particulate organic matter (CPOM) and benthic algae in Chepkoo River, with a view of enhancing environmental and human health. Three sampling sites were purposely selected to capture the effects of clear-cut along this river. It was hypothesized that clear cutting of riparian vegetation had a direct influence on water quality, CPOM quantity and periphyton abundance and diversity. Sampling was done in the months of April to June 2017, and entailed measurements of physico-chemical parameters, water nutrients, collection of CPOM and periphyton at the three sites. Among the physico-chemical parameters measured, temperature differed significantly among the sites, being higher at midstream site (F(2, 24) = 16.423, p < 0.05). Total phosphorous and soluble reactive phosphorus were in high concentration than the other nutrients in the three sites, whereby the midstream recorded the highest mean value of 0.223±0.038 mg/L. However, the mean difference was not statically significant amongst the sampling sites (F(2, 24) = 0.225, p > 0.05). There occurred a significant difference in mean periphyton abundance among the sites (, p < 0.05) with midstream recording the lowest value (Tukey HSD, α = 0.05). The quantity of CPOM (pooled data from the riverbanks) collected among the sites differed significantly (F (2, 24) = 12.427, p < 0.001) with the midstream site having the highest value (Tukey HSD, p < 0.05). The mean difference of CPOM retention within the stream channel was statistically significant (F(2, 24) = 8.053, p < 0.001) with the upstream site recording the highest amount. Vegetation diversity, using Shannon Wiener diversity index indicated that upstream (2.2), > downstream (1.9), > midstream (1.7). Approximately 32% of the plant species were similar among the three sampling sites. This study confirms that reduced canopy cover leads to reduced water quality, periphyton abundance as well as in-stream CPOM along Chepkoo River. County and national government agencies need to do campaigns on the need for afforestation and reforestation of clear-cut sites on the river’s watershed. Such an intervention strategy will lead to better water quality, and improved human and environmental health.

1.1 Background information
Globally, it is estimated that 13 million hectares of forest per year are converted to agricultural land (FAO 2005). Notably, there is reduced landscape restoration and reforestation of about 7.3 million hectares per year (FAO 2005). Some parts of Africa and South America have experienced the highest rate of forest loss that is between 4.3 million and 4.0 million hectares per year (Chopra et al., 2000). DeTroyer et al., (2016), attributed water quality deterioration in East Africa to rapid deforestation. Kiage et al., (2007), estimated the deforestation rate in Kenya to be at 0.3% per year due to agricultural expansion, population growth and industrialization (FAO, 2010). There are 80 countries worldwide, which had stabilized their forest covers by 2010. They had either maintained or increased their forest cover; Kenya is not among these countries (FAO, 2011).

Rivers are lotic ecosystems that receive their energy from primary production by aquatic and other nearby plants, and from externally produced non-living organic matter (Vannote et al., 1980, Cummins et al., 1989). Many studies have described the effect of deforestation on rivers and head water points to be more direct and profound. Reduction in forest cover leads to reduced evapotranspiration and increased runoff as well as sediment and nutrient transport (Kreutzweiser and Capell, 2001; Haggertry et al., 2004; Jackson, 2007; Dewson et al., 2007a, 2007b; Thomson et al., 2009). The significant global impacts of clear-cut in both temperate and tropical forest are the variability in rainfall patterns and the earth’s surface temperature. The hydrological cycle has been weakened by a reduction in moisture circulation, and evapotranspiration models that suggest that about 80% reduction of annual rainfall can be attributed to deforestation (Hasler et al., 2009).

Surface temperatures in some areas are predicted to increase by a maximum of 3˚C, which is caused by a reduction in evaporative cooling that is associated with loss of vegetation (Snyder, 2010). Clear- cut forests are characterized by increased surface runoff and flash flood risk (Bradshaw et al., 2007). There can be an increase of diseases such as yellow fever and malaria due to the removal of forest. Increased temperatures are likely to alter pathogen reproductive cycles (Vittor et al., 2006; Patz et al., 2008). Forests play significant role in capturing runoff, by creating roughness on the ground surface and therefore, reduce the speed of the water, allowing high infiltration rate, which end up reducing the runoff. The trees also help in building up organic matter content that enhances soil fertility and protects rivers from the erosive power of runoff (Depietri, 2015).

Plants loosen the soil, and this increases the infiltration rate of runoff. Sediment removal is affected as they are deposited on the tissues of the plants. There is a high maintenance of organic matter in the soil, which is ideal for facilitating the process of denitrification and many other biochemical processes. Riparian vegetation is also useful in the removal of pollutants, which are dissolved in soil waste, while essential nutrients are incorporated into the plant tissues. Plants play an important role in stabilizing stream and riverbanks and thus help in modifying the temperatures, humidity, and light within the river and the riparian zones (Newman et al., 2014).

Water quality significantly affects the ecosystem functions and ecological processes, some of which support critical habitats for aquatic organisms. Therefore, the aquatic ecosystems are the fundamental part of our environment. According to Wohl et al. (2015), aquatic ecosystems play an integral role in maintaining the quality of water, and thus they are a significant indicator of water quality as well as sustainability of water resources for other uses.

Therefore, clearing of forests adjacent to lotic and lentic ecosystems may lead to losses of stream habitats (Sultana et al., 2014), loss of species, and associated ecosystem services. The naturally occurring drainage is interrupted when the riparian soils are compacted because there is an increase in sedimentation. Furthermore, increase in solar radiation penetrating to the water and this will affect the temperature of the river, which ends up negatively influencing the surrounding activities in the watershed (USEPA, 1995). According to UNEP report (2003), some of Keiyo south forests have been clear-cut for instance the Tumoo Forest, that stand at 1951.99 hectares. Therefore, the primary aim of this study was to determine the effects of clear-cut of Tumoo native forest on the quality of water in Chepkoo River.

Statement of the Problem
Tree clearance at catchment level and along river corridors impacts negatively on river health. Increased temperatures, reduced organic matter inputs and changes in invertebrate community composition and diversity are the likely outcomes associated with clearance of riparian zones. Unstable banks lead to increased sedimentation and siltation of downstream recipient water bodies like lakes and ponds. Water cleaning ability of streams especially nutrient removal associated with agricultural activities is largely lost. This poses health risk to water users especially for domestic purposes. Consumption of contaminated water by resident communities would lead to increased costs of medication and time spent in health facilities. Further, the effects of clear- cut of Tumoo forest on the functionality of Chepkoo River are largely unknown. It is on this basis that a study on Chepkoo River was proposed with a view of establishing a link between deforestation of Tumoo forest through clear-cutting and water quality as well as stream health.

Broad Objective
To determine the water quality, benthic organic matter and periphyton based on levels of riparian corridors clearance at Chepkoo River.

Specific Objectives
1) To determine the physico-chemical parameters (temperature, dissolved oxygen, pH and suspended sediments) of the river water among the sampling sites.

2) To determine nutrient concentrations among selected sampling sites along Chepkoo River.

3) To assess the abundance and diversity of benthic periphyton (diatoms) in Chepkoo River.

4) To determine the variation of benthic coarse particulate organic matter amongst the sampling sites of the river.

5) To assess vegetation composition and diversity at the selected sampling sites.

H01: There is no significant difference in physico-chemical variables (temperature, dissolved oxygen, pH and suspended sediments) of the river among the sampling sites.

H02: The concentrations of nutrients in water are the same among the selected sites along the river.

H03: Periphyton abundance and diversity is the same across the sampling sites.

H04: There is no significant difference in the benthic coarse particulate organic matter among the sampling sites in Chepkoo River.

H05: Composition and diversity of riparian vegetation is similar among the three sampling sites.

Vision 2030 blue print by the government of Kenya under the social pillar envisions an environment that is largely clean, secure and sustainable to support human life. This goal also aim at ensuring water is available and accessible by all (Njagi, 2018). Removal of forest along the river, interfere with the normal functioning of the river by directly influencing the quality and quantity of water. The findings of this study will help achieve Kenyan vision 2030, by meeting the target of having a cohesive and just community with a clean and secure environment.

Sustainable Development Goals 2030, goal 15 focuses on protection, restoration, and promotion of the sustainable use of the terrestrial ecosystems by sustainably managing the forest, combating desertification, halting and reversing land degradation and stopping biodiversity loss. This goal will not be achieved if we cannot start addressing issues of deforestation in local areas. Therefore, the findings from this study will help to meet goal 15 of the SDGs (Osborn et al., 2015). The Kenyan constitution 2010, chapter five aims at protecting the ecosystems, encourage public participation in sustainable utilization of resources as well as sound management of natural resources to achieve development and prosperity of all without damaging the environment. Article 42, of the Kenyan constitution, entitles every citizen to clean and healthy environment and without water in both good quality and quantity, this right will be violated. Therefore, the findings from this study will be of much help to the residents who live near Chepkoo River and other related areas.

There is a need for continuous research and preparation of an inventory of the effects of clear-cut of the native forests on the water quality, for ecological services and ecosystem support. Some of the findings from this study will be used to inform policymaking with respect to land use and land cover management issues. This study thus aims to address the effects of clear-cut of Tumoo forest on water quality in Chepkoo River to enhance human and environmental health. The findings can form a basis of river management in future.

Scope of the study
The study was carried out in Chepkoo River along Tumoo forest, Elgeyo-Marakwet County. Three sampling sites (upstream, midstream and downstream) were selected based on the variability of anthropogenic disturbances and the ease of accessibility. The sites were at stretch of about one kilometer apart to capture the effect of clear cut and after the clear cut downstream. The parameters studied were; temperature, dissolved oxygen, pH, suspended sediment, canopy cover, nutrient loading, benthic periphyton (diatoms), coarse particulate organic matter and vegetation composition. The study was undertaken for three months, from April to June 2017.

Assumptions of the study
Assumptions for this study were:-
i. River water quality is reflective of the human activities on the catchment area.

ii. The quantity of CPOM and abundance of periphyton is reflective of the river’s water quality as well as the riparian vegetation density.

Definition of terms
Clear cut: This is a practice whereby trees are uniformly cut down, leaving less than 10% of the area covered by trees of more than three meters high.

Coarse particulate organic matter: this refers to any organic matter that is greater than 1 mm in size and is found on the riverbank and the river channel.

Environmental health: this refers to the practice of assessing, correcting, controlling and preventing those factors in the environment that can potentially affect the health of the present and future generations adversely.

Nutrients: This refers to nitrates, nitrites, phosphates and ammonia, discharged into rivers through runoff.

Periphyton: They are organisms, which live as a community attached to the stream bottom substrates for instance rocks, woody debris, or vegetation. They include bacteria, algae, protozoa, and diatoms. For this study, only diatom algae was studied this is because their response to nutrients is predictable and can be used to develop nutrient criteria.

Suspended sediment: this refers to the sand, silt and clay-sized particles that are held in suspension because of the turbulence in the water.

Soil erosion: this refers to a process, driven by the lateral movement of water on the land surface and it involves the detachment of the soil particles, the transportation, and storage or sedimentation process of the detached soil.

Water quality: This refers to physical, biological and chemical parameters of water. It involves measuring the condition of water and is normally relative to requirements of biotic species, or to any human needs.

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