Bio

Publications


2013

Maina-Gichaba, C.  2013.  Relief, Physiography and Drainage. Developments in Earth Surface process . Abstract

Kenya's relief stretches from sea level to just over 5000 m at the peak of Mt. Kenya. Combined with its tropical latitudinal location, this relief range creates varied physical environment with characteristics that are almost equatorial sharply contrasting with semi-arid and arid environments. Topography is described as both simple and diverse. Its simplistic form is shown by the fact that the relief can easily be separated into lowlands and uplands while diversity is exemplified by the presence of varied landform types which include Equatorial, Savannah, Aeolian, Glacial, Volcanic and Tectonic. The Kenyan landscape, with its wide variety of forms, is closely linked with such factors as climate, micro-climate, water supply, soils, vegetation and agricultural potential. Some of the sharp contrasts in Kenya’s landscape result from the considerable differences in age of the component landforms. These are now warped and broken by faults in many areas while elsewhere volcanic activity has produced further modifications. Earth movements particularly in late Tertiary, Pleistocene and recent times, have resulted in the formation of the major mountain blocks and Rift Valley systems. These were accompanied by extensive volcanic lava emissions, which cover a significant percentage of the country's land surface. As a consequence of volcanism and earth movements, the drainage has been dislocated, interrupted and modified, and there is hardly a river that has not been affected. Many lakes have been formed in downwarped or downfaulted areas. In coastal regions, the history has been further complicated by Pleistocene changes of sea level. Major physiographic regions seems to be associated with the drainage patterns of the country. A combination of the relief, drainage systems and physiographic regions seem to influence the management and planning of the country’s development strategy. The policy makers must therefore design projects and programs for information gathering, analysis and dissemination on the basis of physical geographic factors as well as the man-made innovative improvements of nature. A superimposition of these attributes through Geographic Information System may show areas that are likely to give the greatest production-increasing effects on the basis of a combination of all the resident attributes.

2009

Jenkins, MW, Maina-Gichaba C.  2009.  Patterns and Sources of Faecal Pollution in the Heavily Impaired River Njoro Watershed Kenya: Findings and Implicaions.. AbstractPatterns and Sources of Faecal Pollution in the Heavily Impaired River Njoro Watershed Kenya: Findings and Implicaions.

Elevated faecal pollution of water bodies poses public health risks for humans as well as livestock, and degrades aquatic ecosystems. This paper presents levels, patterns and sources of faecal pollution detected in a yearlong investigation of the River Njoro watershed, a crucial source of surface and ground water for communities and ecosystems in and surrounding the watershed, including Nakuru Municipality and Lake Nakuru. Under the SUMAWA Project, an extensive survey was conducted of the stream network and numerous point and non-point sources of faecal pollution. Then faecal coliform levels were monitored monthly throughout the River Njoro main stream and Little Shuru tributaly. New gene-based detection methods were tested to distinguish cow from human sources of faecal contamination, and test for markers of Cryptosporidium spp., a water-borne pathogen known to cause severe diarrhoea in very young, old, and immuno-compromised humans and cattle. High levels of faecal water pollution were measured throughout the watershed, averaging 8,000 colony forming units (cfu) of faecal coliform per l00 ml of river water over the year. Periods and incidents exceeding 100,000 cfu/100 ml occurred at l0 out of l5 monitored locations, at some places during the dry season, and nearly everywhere during high runoff months of August and/or July. A pattern of faecal pollution peaking in August at all sites, significantly higher levels detected when cattle were present watering at a site, and the widespread detection of cow genetic source faecal markers, point to livestock, in particular cattle, as the dominant and most widespread likely cause of gross faecal pollution and a possible source of Cryptosporidiunz spp. in the River Njoro Watershed. Detailed findings are presented and actions explored to control identified sources and reduce high pollution levels and their damaging impacts on local ecosystems, livelihoods, and public health.

Mainuri, ZG, Maina-Gichaba C, Wakindiki IIC.  2009.  Soil Use and Management Effects on Aggregate Stability, Organic Matter and Hydraulic Conductivity Within River Njoro Watershed in Kenya. Proceedings of the Sumawa Mau Forest Complex Conference. , Nairobi - Kenya: Sumawa Abstract

There has been tremendous changes in soil use and management in the River Njoro Watershed during the last three decades. Formerly large-scale farms converted into smallholder farms and plantation forests have gradually been lost. These changes in soil use have brought in different soil use and management approaches that have triggered soil erosion and other forms of land degradation. Up to 8.6 Kg of soil, loss per hectare from the cultivated soils has reportedly been lost in one storm. This massive soil loss was probably due to reduced aggregate stability and hydraulic conductivity. The objective of this study was to trace the changes in soil use and determine their effects on aggregate stability, organic matter and hydraulic conductivity. The study undertook a semi detailed soil survey of the watershed through a three-tier approach comprising image interpretation, field surveys and laboratory analysis. The measured variables in the soil were analysed using a two - way ANOVA and correlation analysis. The study found the major land uses to be forest, agriculture, grassland, and Wetland, and also observed a strong soil — landscape relationship within the Watershed. Soils of slopes were moderately to severely eroded, shallow and les developed whereas those on summits, pen plains, uplands, plateaus and valleys were deep and well developed. Aggregate stability Was in the order of forests > grasslands > agriculture Wetland. The mean Weight diameter in various land uses Was 0.68, 0.64, 0.58, and 0.41 respectively. Hydraulic conductivity Was in the order of forests > agriculture > grasslands > wetland. Hydraulic conductivity significantly correlated negatively With bulk density and Lay content. We concluded that land use changes that reduced the amount of organic matter significantly reduced aggregate stability. In addition, soil use and management activities that reduced organic matter content significantly lowered hydraulic conductivity and therefore likely to contribute to erosion and other forms of land degradation.

Key words: land use, land management, land degradation

Jenkins, MW, Maina-Gichaba C.  2009.  Patterns and Sources of Faecal Pollution in the Heavily Impaired River Njoro Watershed Kenya: Findings and Implicaions. Proceedings of the Sumawa Mau Forest Complex Conference. , Nairobi - Kenya: Sumawa Abstract

Elevated faecal pollution of water bodies poses public health risks for humans as well as livestock, and degrades aquatic ecosystems. This paper presents levels, patterns and sources of faecal pollution detected in a yearlong investigation of the River Njoro watershed, a crucial source of surface and ground water for communities and ecosystems in and surrounding the watershed, including Nakuru Municipality and Lake Nakuru. Under the SUMAWA Project, an extensive survey was conducted of the stream network and numerous point and non-point sources of faecal pollution. Then faecal coliform levels were monitored monthly throughout the River Njoro main stream and Little Shuru tributaly. New gene-based detection methods were tested to distinguish cow from human sources of faecal contamination, and test for markers of Cryptosporidium spp., a watcr-borne pathogen known to cause severe diarrhoea in very young, old, and immuno-compromised humans and cattle.

High levels of faecal water pollution were measured throughout the watershed, averaging 8,000 colony forming units (cfu) of faecal coliform per l00 ml of river water over the year. Periods and incidents exceeding 100,000 cfu/100 ml occurred at l0 out of l5 monitored locations, at some places during the dry season, and nearly everywhere during high runoff months of August and/or July. A pattern of faecal pollution peaking in August at all sites, significantly higher levels detected when cattle were present watering at a site, and the widespread detection of cow genetic source faecal markers, point to livestock, in particular cattle, as the dominant and most widespread likely cause of gross faecal pollution and a possible source of Cryptosporidiunz spp. in the River Njoro Watershed. Detailed findings are presented and actions explored to control identified sources and reduce high pollution levels and their damaging impacts on local ecosystems, livelihoods, and public health.

2007

Baldyga, TJ, Miller SN, Driese KL, Gichaba CM.  2007.  Assessing Land Cover Change in Kenya’s Mau Forest Region using Remotely Sensed Data . The Authors Journal Compilation. Abstract

Kenya's Rift Valley has been undergoing rapid land cover change for the past two decades, which has resulted in ecological and hydrological changes. An effort is under way to quantify the timing and rate of these changes in and around the River Njoro watershed located near the towns of Njoro and Nakuru using remote sensing and geographic information system (GIS) methods. Three Landsat TM images, representing a 17-year period from 1986 to Z003 in which the area underwent a significant land cover transition, were classified and compared with one another. Vegetation diversity and temporal variability, common to tropical and sub-tropical areas, posed several challenges in disaggregating classified data into sub-classes. An iterative approach for the resolving challenges is presented that incorporates unsupervised and supervised classification routines in coordination with knowledge- based spatial analyses. Changes are analysed at three spatial scales ranging from the highly impacted and deforested uplands to the watershed and landscape scales. Land cover transitions primarily occurred after 1995, and included large forest losses coupled with increases in mixed small-scale agriculture and managed pastures and degraded areas. These changes in cover type are highly spatially variable and are theorized to have significant impacts on ecological and hydrologic systems-with implications for environmental sustainability.

Keywords: accuracy assessment. deforestation, Landsat, scale

J., BT, Miller SN, C.M. G, W. S.  2007.  Suitability of the Automated Geospatial Watershed Assessment (AGWA) Tool in Hydrologic Response and Land Cover Change in River Njoro Watershed, Kenya . Suitability of Geospactial Watershed Assessment. Abstract

Rapid land cover changes occurring in the Rift Valley of Kenya are altering the hydrologic response of critical watersheds. Four Landsat scenes from the past 18 years were used to develop a land cover classification scheme for the Njoro River watershed. These data were input to the Automated Geospatial Watershed Assessment (AGWA), a geographic information system (GIS) tool. AGWA was used to parameterize and run the Soil and Water Assessment Tool (SWAT), a hydrologic model suitable for assessing land cover change impacts on hydrologic response. The automated parameterization routines in AGWA are designed for US soil and land cover data sets and require inputs for terrain, soil, land cover, climate and rainfall. Climate, soil and terrain data were built for the watershed using historical data and field work, and classified land cover data were created using supervised and unsupervised classification and verified in the field. Techniques and methods were created to transform Kenya data sets into suitable formats for AGWA. Preliminary findings indicate the suitability of this type of analysis for watershed assessment in Kenya; changes in landscape and land use are reflected in significant changes to simulated hydrologic results.

Key words: Land cover change, Watershed, GIS, Hydrologic response

Shivoga, WA, Muchiri M, Kibichi S, Odanga J, Miller SN, Baldyga TJ, Enanga EM, Gichaba MC.  2007.  Influences of Land Use/ Cover on Water Quality in the Upper and Middle Reaches of River Njoro, Kenya . Lakes & Reservoirs: Research and Management . : Blackwell Publishing Asia Pty LTD Abstract

Data from 10 sampling sites along the River Njoro are used to examine the contribution of nutrients from upstream land uses draining each of the sampling sites. The data also are used to assess whether both the proportion of land uses and the size of the subwatersheds account for the variability in water quality in the River Njoro watershed. Geographical Information System analysis was used to determine the spatial distribution of land-cover types and subwatersheds contributing run-off to the sampling sites in the River Njoro. Standard Digital Elevation Model-based routines were used to establish the watershed area contributing run-off to each sampling site. Water and sediment samples were collected for chemical analysis, and the nutrient levels were related to the upstream land-use types and the size of the subwatersheds. The mid-stream portion of the River Njoro (near Egerton University) accounts for the highest nutrient contributions. The percentage contribution is magnified by additions from industrial, human settlements and agricultural land uses around the University. There is a significant decrease in nutrient levels downstream, however, indicating natural purification as the river flows through an area of large-scale farming with intense, well-preserved riparian and in-stream vegetation. Steep slopes of the land upstream of Egerton University enhance erosion and nutrient losses from those subwatersheds. Mixed small-scale agricultural and bare lands contribute over 55% of the phosphorus load to the upper and mid-reaches of the River Njoro. The size of the subwatershed accounts for about 53% of the variability in the soluble phosphorus in the river. The land~use subwatershed proportions are important for characterizing and modelling water quality in the River Njoro watershed. Upland land uses are as important as near-stream land uses. We suggest that conservation of intact riparian corridor along the river and its tributaries contributes significantly to natural purification processes and recovery of the ecological integrity of the River Njoro ecosystem.
Key words: Ecological integrity, ‘natural purification, nutrient levels, riparian zone, subwatersheds, upland land use, water quality.

Kundu, PM, Chemelil MC, Onyando JO, Gichaba M.  2007.  The Use of GIS And Remote Sensing to Evaluate the Impact of Land Cover and Land Use Change on Discharges in River Njoro Watershed, Kenya. Journal of World Association of Soil and Water Conservation. J2-08 Abstract

River Njoro watershed represents diverse hydrological environments in Kenya with considerable land use changes. It was once covered by rich vegetation of highland evergreen forests which extended from the Mau hills and turned into woodland dominated by acacia trees in the Rongai-Njoro plains. it was first opened up for settlement in i889 when the Uganda Railway passed through it. Large ranches and farms were started and the area grew to become a major agricultural region. An increase in population between the 1970s and 1990s led to deforestation, land fiagmentation and cultivation of wetlands to meet the demands for food, fuel Wood and housing. To evaluate the impact of land use and land cover changes, remotely sensed data, Geographical Information System (GIS) and ground survey methods Were used. A 322% land use change from forest and Woodland to agriculture and built-up was determined from the analysis of the imagery and ground survey. This impacted negatively on the hydrology of the area, resulting in reduced infiltration, high peak runolf, reduced discharges and “drying up” of many boreholes. The study provided results which could be extrapolated to similar Watersheds, hence the approach could be adopted for Watershed management in Kenya.

2005

Maina-Gichaba, C, Shivoga WA, Enanga EM, Kibichii S, Miller SN.  2005.  Sediment loading on inland lakes/wetlands: A case study of lake Nakuru, Kenya. Proceedings of the 11th World Lakes Conference. :389-391., Nairobi - Kenya Abstract

Total suspended sediments and discharge were studied on the river mouths and sewage drain that. empty into Lake Nakuru, Kenya. Total suspended sediment loading into Lake Nakuru is a function of the concentration of total suspended solids and discharge at each mouth. The study was conducted at the mouths of rivers Njoro, Makalia, Nderit, Baharini springbrook and Sewage drain. In situ measurements of discharge were done, at each mouth, and 500ml water samples were taken and determination of total suspended solids done in the laboratory. Historical data was also used to provide typical discharge and total suspended solids values for each month. Loading was then calculated for each river mouth and the sewage drain. Although River Nderit had the highest concentration of total suspended solids, than rivers Njoro and Makalia, it delivered a lower amount of total suspended solids due to its lower discharge volume. River Njoro was found to deliver the most loads of total suspended solids (70%) despite having a lower concentration of total suspended solids followed by Makalia (21%), Nderit (4%), Sewage drain (4%) and Baharini (1%)in that order. Baharini is fed by a number of clean water springs emanating from the Lake Nakuru National Park which is a protected area. All the other rivers, especially Njoro and Makalia drain rural and urban watersheds with intensively cultivated easily eroded landscapes. This study shows that rivers emanating from outside protected areas under agriculture and urbanization contribute the highest to lake sediment loading and management of sedimentation of Lake Nakuru should focus mainly on soil management in the landscape.

Key words: discharge; loading, total suspended solids

Baldygal, TJ, Miller SN, Driese KL, Gichaba MC.  2005.  Using Landsat Imagery to Analyse Land Cover Change in the Njoro Watershed, Kenya. XX International Grassland Congress: Offered Papers. , Wageningen- Netherlands: Wageningen Academic Publishers Abstract

Keywords: land cover, remote sensing, Landsat

INTRODUCTION

In developing nations where resources are scarce and increased population pressures create stress on available resources. methods are needed to examine effects of human migration and resultant changes in land cover. Widespread availability and low cost of remotely sensed imagery and Geographic Information Systems (GIS) are making such methods a reality to develop quantitative resource mapping and land cover change detection in developing nations (Sheng et al.. l997). However, difficulties arise in tropical regions When trying to analyse traditional vegetation bands (Bands 3 and 4). or indices such as NDVI because saturated pixels limit spectral distinction.

Onyando, JO, Okelo MO, Gichaba CM, Shivoga WA, Miller SN.  2005.  Micro-field assessment of soil erosion and surface runoff using mini rainfall simulator in upper River Njoro watershed in Kenya. XX International Grassland Congress: Offered Papers. , Wageningen- Netherlands: Wageningen Academic Publishers Abstract

Keywords: rainfall simulator, erosion, run-off, agricultural land use

INTRODUCTION

Soil erosion and surface runoff are consequences of integration of several factors and processes within a catchment. The use of a rainfall simulator and run off plots provides a valuable research tool and are often used in soil erosion and surface runoff studies. Cheruiyot (1984) used this approach to study infiltration rates and sediment yield in Kiboko, Kenya. The present study used the same method but with a mini-rainfall simulator (Kamphorst, 1987) to study the effects of different land use treatments on soil loss and surface runoff.

Shivonga, WA, Muchiri M, Kibichi S, Odanga J, Miller SN, Baldyga TJ, Gichaba CM.  2005.  Impact of land use on water quality in River Njoro Watershed, Kenya. XX International Grassland Congress: Offered Papers. , Wageningen- Netherlands: Wageningen Academic Publishers Abstract

Keywords: upland land use, subwatershed, downstream water quality, riparian zone

INTRODUCTION

Water resources Within the River Njoro watershed have become degraded due to high population growth rate and change in land use upsetting environmental stability. Land cover classification using Landsat images (Baldyga et al., 2004) shows loss of about 20% of forested areas between 1986 and 2003 in the Watershed. The forested and large-scale farm areas have been converted mainly into srnall-scale mixed agriculture and human settlements. These changes have impacted negatively on the ecological integrity and hydrologic processes in the watershed (Shivoga. 2001) but little is known about the influence of specific land uses on water quality of the river.

2004

Baldyga, TJ, Miller SN, Shivoga WA, Gichaba CM.  2004.  Land cover change detection in the river Njoro watershed: a landscape in transition.

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