S. M. Onywere

The Impact of Land Use Activities on Vegetation Cover and Water Quality in the Lake Victoria Watershed

The impact of land use activities on loss of vegetation cover and water quality was assessed in three selected sites within the Lake Victoria Basin using remote sensing technologies and standard water quality analysis techniques. The three study sites were: (i) Nzoia River Basin (Kenya), (ii) Nakivubo Wetland (Uganda) and (iii) Simiyu drainage basin (Tanzania). Lake Victoria is the second largest fresh water lake in the world and is served by a drainage basin area of over 193,000 km 2 , traversing five East African Community States; Kenya, Uganda, Tanzania, Rwanda and Burundi. This paper examines the impact of land use activities on vegetation cover and water quality based on remote sensing and Geographical Information Systems analysis combined with chemical and physical water analysis. The quality of the effluent generated by the industries found within the study sites and their effects on downstream discharge was also determined. Pesticide residues in soil and water samples were determined using analytical standard methods. Soils from some selected fields in Nzoia River basin showed high levels of compounds such as aldrin, dieldrin, endosulfan, DDT, and endrin which are together referred to as persistent organic pollutants (POPs). The physical and chemical analysis of water quality revealed high levels of phosphates and nitrates along the agricultural zones of River Nzoia Basin. The satellite images revealed that in all the three study sites land vegetation cover has continuously reduced in size. The extent of environmental degradation caused by agricultural, domestic and industrial wastes and how this affects loss of vegeta- tion cover and water quality is discussed.

Use of Remote Sensing Data in Evaluating the Extent of Anthropogenic Activities and their Impact on Lake Naivasha, Kenya

This study investigated the anthropogenic activities in Lake Naivasha Basin and how they are influencing the quality of water resources. The poor quality of water in the lake is seen from the presence of water hyacinth (Eichhornia crassipes) and is a reflection of nutrient rich waters. The water hyacinth in Lake Naivasha is associated with major negative economic and ecological impacts. The intensity of land use within the basin was mapped from multispectral Landsat satellite imagery of 1986 (TM) and 2000 (ETM) and SPOT imagery 10 m (resolution) of 2007. From interpreted data, the surface area of the Main Lake has decreased from 134.9 kmin 1986 to 117.5 kmin 2007 (12.9%); that of papyrus and wetland grasslands along the lake shore decreased from 54.6 kmto 34.3 km� (37.2%) and that of the horticultural and irrigated farms increased by 103.3% from 45.1 kmto 91.7 kmin the same period, placing great pressure on both the quality and quantity of the lakes water resources. Information obtained from the Fisheries Department in Lake Naivasha show that the fishery production declined from 513 to 110 tons in the period considered. The Naivasha Municipal Council records indicate a 30% decline in the water it supplies to Naivasha Town from 10,000 m 3 to 7,000 m 3 in the same period despite the increase in population. The decline was attributed to many factors among them the presence of water hyacinth and the decline in water quantity due to increased human activities.

Impact of Short-Term Flooding on Livelihoods in the Kenya Rift Valley Lakes

Short term flooding episodes can have devastating impacts on both the natural processes and community livelihoods. The Lakes Baringo, Bogoria, Nakuru and Naivasha lie within the arid and semi-arid northern part of the central rift valley in Kenya and are vulnerable to climatic variability with particular challenges related to water resources. This chapter presents the extent of flooding of four lakes in the central rift valley in Kenya over the period from January 2010 to December 2014. Documentation of the changing spatial extent of the water levels in the four lakes was conducted using Geographic Information Systems (GIS) digital techniques and information extraction and representation from selected Landsat satellite image data for the years 2010, 2013 and 2014. Results show an increase in the lake levels over the study period and the extent of flooded areas that is highly influenced by the geomorphology of the environs of the lakes. The rising lake levels have affected the ecology of the riparian areas of the lakes thus impacting on the biodiversity, wildlife, tourism infrastructure and the settlements around the lakes. The communities settled especially around Lake Baringo have been displaced and their livelihoods affected.

Assessing the Challenge of Settlement in Budalangi and Yala Swamp Area in Western Kenya Using Landsat Satellite Imagery

The Budalangi area of Kenya exhibits high levels of rural poverty despite its natural resources potential and favourable climate. The area was mapped using multi-temporal remote sensing image data from 1973 to 2009 and participatory data collection. Floods are a recurrent environmental hazard and impede access to environmental resources and agricultural production. The physical setting of Budalangi at the floodplain of Nzoia River and increased runoff from degraded catchments are contributory factors to the flooding. Floods lead to disruption of human settlements and destruction of crops, shelter, dykes and infrastructural facilities. Disease outbreaks also increase due to destruction of sanitation facilities and relocation of settlements in makeshift camps. This implies that the policy measures that have been instituted by the government to mitigate the problem have had dismal impact in the Budalangi and Yala Swamp area. The degradation of the catchment is reflected in its sediment loading and deposition into Lake Victoria which has seen the morphology of the coastline at the mouth of Nzoia River and the aerial coverage by water in the lake change over the years. The overall loss in the area under Yala Swamp is 54 Kmfrom 186 Kmin 1973 to 132 Kmin 2009. The encroachment has significant implication on the wellbeing of the Yala Swamp and the Nzoia Floodplain ecosystem. The study therefore underscores the need to evolve an integrated watershed management plan for effective management of Budalangi and Yala Swamp area and the region in general.

Application of GIS and remote sensing techniques in frost risk mapping for mitigating agricultural losses in the Aberdare ecosystem, Kenya

Frost is a perennial agricultural hazard that normally causes crop damage leading to huge agricultural losses within the Kenyan highlands; aggravated by inadequate information on frost. This research mapped frost hotspots within the Aberdare and Mount Kenya regions and identified the extent of arable land under frost risk while establishing the trend of minimum temperature occurrences between the years 2000 and 2013. Minimum temperature values were extracted from daily Moderate Resolution Imaging Spectroradiometer land surface temperature data-sets, and frost risk categorized into very severe frost (<250 K), severe frost (250–260 K), moderate frost (260–270 K), minor frost (270–280 K) and areas of no frost. Concentration of frost (<273 K) was mapped within regions above 1500 m asl and occasional occurrences within valleys lower than this altitude with recurrent occurrences in the months of April, May, July, August and November. Elevation, land surface convexity and humidity were found to influence frost occurrence. Improved agricultural practice to mitigate against losses is recommended.

Application of satellite remote sensing techniques in land use and land cover pattern analysis of the Nakuru-Nyahururu area

SPOT and LANDSAT-5 TM space images have been utilised to analyse land use cover characteristics and patterns in a section of the Aberdare Detachment system sub-basin, the Nakuru-Nyahururu area, Kenya. Good ground resolution of both data show significant details of the land use cover patterns and linear patterns of fault scarps. The synoptic view suggests, NNE, NE and NW trending scarps and associated grabens and plateaus. Spectral analysis of photographic products is made. A multitemporal approach is adopted and based on image characteristics, four areas of land use cover types have been identified: (i) agricultural and forest covered areas (ii) semi-arid intensely fault dissected north west (iii) down-faulted, tilted fault blocks (plateaus) (iv) Menengai volcanic caldera. A ground truth survey is made and with collateral data maps of land use are compiled.<<ETX>>

Sustainable Water Resources Management for Food Security in Kenya: Case of Bwathonaro Catchment

Food security is important in Kenya today. Bwathonaro sub-catchment in Tana catchment is experiencing food insecurity and severe water related challenges due to high population pressure and over-reliance on irrigated agriculture for livelihood. Bwathonaro river supports irrigated agriculture, which is a major source of livelihood for people in the watershed. These challenges include: water pollution, inappropriate solid waste disposal, illegal water abstraction and/or over-abstraction of water, inefficient irrigation practices, encroachment on and drainage of wetlands as well as inappropriate use of agrochemicals in wetlands. The specific objectives of the study were to 1) document current status of water resource use; 2) propose a strategy for enhancing subsistence food crop farming within the existing khat (miraa) farming system; 3) promote efficient irrigation systems that reduce water use conflict and enhance equitable distribution, and 4) work with community to improve water quality and quantity. The study adopted a four-pronged approach in the data collection procedures, namely: socio-economic surveys, participatory approaches, biophysical data and geospatial tools. Results showed that water use conflicts are persistent in the catchment. However, one Water Resource User Association (WRUA)-BWARUA, has shown consistent progress towards managing water resources for food security. The WRUA has undertaken a number of activities including ensuring that water abstractors observe permit conditions, undertaking surveillance of polluters, awareness creation on protection of wetlands, springs and river banks among other activities in the catchment. The impact of these activities has been positive and includes: reduction of conflict over water, reduction in pollution, more water flowing downstream and more water availability in the catchment for diverse uses including irrigation for agriculture, livestock and wildlife. Such practices could be used in other sub-catchments of Kenya as showcases to facilitate the sustainable use of scarce water resources for the benefit of all stakeholders.