© Springer International Publishing Switzerland 2016. Fruit fly control and management in Africa has been the topic of several scientific investigations resulting in diverse sources of knowledge on the topic. Despite the existence of this knowledge, frequently it is not readily accessible to all targeted beneficiaries; this can be due to, for example, the remote locations of farms and the complexity of the knowledge. However, recent technological developments such as web technologies and networking allow for the engagement and participation of stakeholder groups in the acquisition and dissemination of knowledge and these technologies can also be applied to fruit fly knowledge. In order to facilitate this stakeholder participation in fruit fly knowledge sharing, the relevant domain knowledge needs to be available in a format that can support stakeholder engagement, preferably through the Web. Fruit fly knowledge has not been modelled in this manner and this paper reports on an investigation to model and capture the relevant domain knowledge using ontologies. The objective of this work is thus the development of the domain ontology and its evaluation using a prototype stakeholder participation system for fruit fly control and management that was capable of utilising the ontology. We describe our findings on the use of ontology technologies for representation of fruit fly knowledge, the fruit fly ontology developed, as well as a prototype Web-based system that uses the ontology as a source of knowledge.

The research discussed in this book sought to penetrate the functional role fo teachers and students’ attitudes towards Christian Religious Education in Kenya. A mixed methods (qualitative and quantitative) approach was employed with the investigations being ‘ex post facto’ in design. A random stratified procedure was employed to select the constituents of the sample. The sample consisted of 49 teachers and 909 students. The methodology, findings, discussion, conclusions and recommendations of the research are presented in the book.

Background Developing countries have limited air quality management systems due to inadequate legislation and lack of political will, among other challenges. Maintaining a balance between economic development and sustainable environment is a challenge …

In Kenya, welding services are extensively employed in both the formal and informal sectors. The needs continue to increase with increasing population, infrastructure and vehicle fleet, and economic development. Welding need is even currently very important in support of …

Land use and land cover changes are important processes that influence the dynamics of human-wildlife conflicts. Effective management of human-wildlife conflicts requires the participation of local communities and other stakeholders. However, local communities need to identify and understand resource use change and their role in the process, so as to facilitate uptake of appropriate land resource management strategies aimed at counteracting human-wildlife conflicts. Approaches aimed at changing local community behavior towards natural resource use require appropriate technologies that bridge the technology and knowledge gaps between policy makers and local communities. PGIS was used to assess and educate local communities on land use and land cover changes as well as visualize the problems associated with resource changes. Local communities were found to be significantly knowledgeable about resource changes and their causes. PGIS compared well to conventional GIS analysis and therefore an appropriate technology for analysing and monitoring landuse and land cover changes.

A rapid non-destructive, multi-elemental and ultra-sensitive analytical technique of engine oil analysis is described. Using" an x-ray excitation source and Si (Li) detector for the1 measurements, the deterioration of an internal combustion engine) is evaluated from results …

Forest landscape restoration (FLR) aims to regain ecological integrity and enhance human well-being in deforested or degraded forest landscapes. Despite its positive connotations, successfully implementing significant FLR will often involve considerable conflict. The purpose of this chapter is to present fundamental principles for managing FLR conflicts. The chapter portrays FLR as a social and political process in which there is no “single” correct view of reality: “good forestry” or “bad forests” are value-laden social constructions that transcend objective facts. If not recognized, this alone can lead to misunderstanding and conflict. Social constructions often emerge and evolve through public discourse – the verbal communication, talk, or conversation among people. Accordingly the discourse-based approaches to conflict management can contribute meaningfully to FLR. Examining the various discourses within a conflict situation can improve mutual understanding, reveal salient aspects of the situation, and strengthen relationships as a foundation for problem-solving. Masters of FLR conflict management must be able to: (a) read the cultural-institutional context, (b) understand people, and (c) create an environment of constructive communication, fair power distribution, and strong incentives.

The effect of global climate change on the built urban environment, especially installed infrastructure for the
delivery of essential services, will be particularly severe and even more so for developing countries where
resources to deal with anticipated impacts are lacking. Because the delivery of wet services is dependent on
water resources and tends to be an energy intensive operation, water and wastewater utilities will be most
vulnerable to the impacts of climate change. It is therefore imperative that the providers of these services embark on a programme of proactively adapting to the impacts of climate change and mitigating greenhouse gas emissions through improved pumping efficiencies. Because adaptation can take on many forms, utilities must apply logic and rational thinking to this process and prioritize interventions that are most likely to cost effectively address identified
impacts.

This study analyzed changes in natural resources in Machakos District of Kenya using participatory approaches. The results show that natural resources have decreased since the ranch became a settlement scheme. Natural forests decreased, vast land was cleared, rivers dried-up while soil erosion, drought, temperatures and land degradation increased. Land productivity declined and most farmers abandoned the traditional crops for modern high value crops. However, farmers adopted various coping strategies. Drought resistant crops, early maturing crops and water harvesting were some of the strategies adopted by farmers. The results also show that resource base management at the community level was still a challenge and a lot of investment needed to be made in this area. As part of the study, farmers knowledge of changes in natural resource use was assessed in a resettlement area. Over a period of about 50 years, significant land degradation has occurred as a result of increased population pressure, poor natural resource management and climate change effects. This was reflected in poor/low land productivity and reduced availability of water. Farmers responded by moving away from growing indigenous crops to growing short-duration crop

Ambient aerosol particles smaller than 2.5 {mu} m (PM {sub 2.5}) are getting more and more attention worldwide. While legal focus is mainly on sample mass, the composition of the particles is an important research field gaining increased interest. The interest is not only …

Gender mainstreaming is crucial in soil and water conservation initiatives. The existing technologies though, as designed, are expected to be gender neutral, lead to gender differences at the adoption stage. This was confirmed during a study conducte d in Kathekakai settlement scheme, Machakos district where despite both men and women participating in soil and water conservation initiatives, women’s efforts to adopt the recommended technologies were hampered by their limited access to authoritative infor ma- tion and lack of control over land. Women though playing major roles as farmers (64.6%), could not make key decisions on land u se. Previous reports indicate that the women in Machakos district contributed significantly to soil and water conservation efforts in the mid 1980’s leading to terracing of over 70% of the district. Gender mainstreaming efforts need to be enhanced for achievement o f sustainable and effective soil and water conservation for improved agricultural production and livelihoods

Coffee Berry Disease which affects green Arabica coffee (Coffea arabica) berries is caused by the fungus Colletotrichum kahawae and is a major problem in Arabica coffee production in African countries. Breeding for resistance to this disease is therefore to a major priority in these countries avoid intensive chemical usage for its control. Recently, microsatellite and Amplified Fragment Length Polymorphisms (AFLP) markers for a gene conferring resistance to the disease were identified and mapped onto the chromosomal region carrying the gene. To improve the repeatability of the AFLP markers, four of the marker bands were selected for cloning and sequencing to facilitate specific primers to be designed. Three of the resultant primers did not amplify products that exhibited polymorphism characteristic of the parent AFLP bands; but one primer pair amplified a product that dominantly identified the presence of the parent AFLP marker at an optimum temperature of 62°C followed by electrophoresis in agarose. The reliability of the designed primers was confirmed by analysis in 95 plants from a F2 population previously used to map the chromosomal fragment carrying the resistance. The importance of the results in enhancing the utility of the parent AFLP marker in relation to analytical costs and position on the chromosomal fragment is discussed.

Contribution of scientific research to local and international journals from Africa and indeed Kenya is weak in comparison to other regions. One of the main problems is the non-availability of reliable and affordable analytical instrumentation. Energy-Dispersive X-ray …

[en] This project undertook various studies monitoring workplace environments and assessing some occupational health status. The studies included monitoring levels of airborne particulate matter (APM), natural background radiation, emissions inventory …

There have been very few studies in Kenya on aerosols despite the global demand on aerosol ground studies in the perspective of climate and the human well being. Therefore, atmospheric aerosol studies became the basis of the work covered in this thesis which …

guyton

Vehicle emissions have profound implications in human health and welfare, ecosystems and on climate (Finlayson-Pitts and Pitts Jnr., 12000; IPCC, 2001; Cacciola et aI., 2002). These emissions include particulate matter (PM), NOx (NO+ N02), volatile organic …

There have been very few studies in Kenya on aerosols despite the global demand on aerosol ground studies in the perspective of climate and the human well being. Therefore, atmospheric aerosol studies became the basis of the work covered in this thesis which …

Kenya’s agricultural sector accounts for 20–30% of the gross domestic product (GDP). Of this, the livestock sector alone makes a contribution of about 50%. Thus, livestock contributes heavily to the GDP and food security of its population. It also provides the necessary thrust for other forms of development in the country. Recent statistics indicate that currently over 50% of the country’s livestock population is based in the arid and semi-arid lands (ASALs), which form about 80% of the country’s land area. However, comparative international statistics show that livestock contributes 88% of the total agricultural output in Botswana even though the country has half Kenya’s livestock population and is of less agricultural potential. Thus, there is a huge potential contribution that livestock can make to the Kenyan national economy. Unfortunately, this sector receives only 10% of the government’s agricultural expenditure and less than one per cent of total spending, yet it is estimated that Kenya’s potential to export livestock products if adequately exploited would earn more than the earnings from tea and coffee combined. This then calls for new thinking about livestock development strategies to harness the arid landsThe livestock sector accounts for 90% of employment and more than 95% of household incomes in the ASALs. Most of the livestock slaughtered in major urban centres originates in these areas, with an annual slaughter of about 1.6 million Tropical Livestock Units. Kenya’s livestock from the ASALs is worth Kshs 60 billion (US$800 million). The internal livestock trade in trade in thepastoral areas alone nets in about 6 billion shillings (US$80 million )a yearIn the arid areas of the ASALs, arable crop production is not possible without some form of irrigation; while in semi-arid areas rainfall may be sufficient for certain types of crops, requiring special management techniques. Therefore, except for the areaunder cropping, the rest of the arid areas is used for livestock.......

Abstract
Winam Gulf is a large (surface area ~ 1400 km2) and shallow (<20 m) bay of northeastern Lake Victoria with only one connection to the open lake through Rusinga Channel. To understand the exchange dynamics between Winam Gulf and the offshore waters of Lake Victoria and the hydrodynamics of the region, field studies were carried out from Apr. 22-May 4 and Aug. 5-16 of 2005. A meteorological station (shortwave, total radiation, air temperature, relative humidity, wind speed and direction), thermistor chain (0.75 m vertical resolution) and ADCP (40cm vertical resolution) were deployed in Rusinga Channel in a depth of 20 m. Similarly, at an offshore station in northeastern Lake Victoria another thermistor chain was deployed in a water depth of 40 m along with wind speed and direction sensors.

Over both field campaigns the exchange dynamics through Rusinga Channel behaved similar to a tidally- driven system with surface level fluctuations of between 5-15 cm at the ADCP location, and much larger excursions at the eastern end of Winam Gulf. In general, these surface level movements led to barotropically driven flows into the Gulf during rising surface levels and currents towards the open lake during falling lake level. The frequency of these currents was found to vary between 6 and 12 hours and current speeds ranged from 10-50 cm s-1. Field data and ELCOM simulations indicate that despite the high current velocities in the channel the net exchange is low due to the oscillatory nature of the forcing. This implies that the Gulf is relatively decoupled from the main lake.

Key words: Lake Victoria, Exchange flow, Flushing times

The Arpolo gullying control project in the West Pokot Region of Kenya is described. This is an example of conservation work done to protect the Arpolo dispensary which cost >KES350,000 to put up and serves about 3,000 people and is threatened by a fast-growing gully. The initial proposal for a concrete wall in the first phase of implementation was not feasible since it would be undermined during the rains. The alternative was to plan, design and apply water-harvesting methods and implement biological measures that would reduce the erosive energy of the surface runoff. The design of the water-harvesting structures is shown. The success of the project shows that land and water management requires skillful planning and design, especially where soils are vulnerable to erosion. The physical and chemical properties of the soils in the area are described. Given proper hydraulic designs, water-harvesting measures are still a reliable means of soil conservation.

The Arpolo gullying control project in the West Pokot Region of Kenya is described. This is an example of conservation work done to protect the Arpolo dispensary which cost >KES350,000 to put up and serves about 3,000 people and is threatened by a fast-growing gully. The initial proposal for a concrete wall in the first phase of implementation was not feasible since it would be undermined during the rains. The alternative was to plan, design and apply water-harvesting methods and implement biological measures that would reduce the erosive energy of the surface runoff. The design of the water-harvesting structures is shown. The success of the project shows that land and water management requires skillful planning and design, especially where soils are vulnerable to erosion. The physical and chemical properties of the soils in the area are described. Given proper hydraulic designs, water-harvesting measures are still a reliable means of soil conservation.

This paper outlines the development of a new methodology to modify and improve the indigenous practices of soil fertility management in Eastern and Southern Africa and suggests requirements for involvement by collaborating institutions. It provides a brief history of the Tropical Soil Biology and Fertility (TBSF) Programme in Africa, ongoing resource integration work in Zimbabwe, proposed work in Kenya and team development in Zimbabwe.

This paper outlines the development of a new methodology to modify and improve the indigenous practices of soil fertility management in Eastern and Southern Africa and suggests requirements for involvement by collaborating institutions. It provides a brief history of the Tropical Soil Biology and Fertility (TBSF) Programme in Africa, ongoing resource integration work in Zimbabwe, proposed work in Kenya and team development in Zimbabwe.

The effects of three different micro-catchment sizes on survival and growth of plant species was assessed and success in establishment and growth of Croton megalocarpus and Cassia spectabilis was compared in a semi-arid region of Kitui District, Kenya. Both species were planted in 25 x 25 cm, 45 x 45 cm, and 65 x 65 cm spherical micro-catchments. Height and diameter were measured and a survival count was taken. Results show that then micro-catchment size influenced (P>0.05) lateral growth of both species. Lateral growth of C. spectabilis in the smaller two micro-catchments (3.66 and 4.60 cm, resp.) was not significantly different (P>0.05), but was less than in the largest micro-catchment(5,31 cm). These results indicate that the two species are suitable for afforestation in these areas and that their survival is not limited by provision of a catchment in the area.

The effects of three different micro-catchment sizes on survival and growth of plant species was assessed and success in establishment and growth of Croton megalocarpus and Cassia spectabilis was compared in a semi-arid region of Kitui District, Kenya. Both species were planted in 25 x 25 cm, 45 x 45 cm, and 65 x 65 cm spherical micro-catchments. Height and diameter were measured and a survival count was taken. Results show that then micro-catchment size influenced (P>0.05) lateral growth of both species. Lateral growth of C. spectabilis in the smaller two micro-catchments (3.66 and 4.60 cm, resp.) was not significantly different (P>0.05), but was less than in the largest micro-catchment(5,31 cm). These results indicate that the two species are suitable for afforestation in these areas and that their survival is not limited by provision of a catchment in the area.

Stover placement (surface mulch, incorporated or a mixture of mulch and incorporation) was compared with stover removal in the presence and absence of 50kg N fertilizer/ha in trials over two successive seasons in continuous maize cropping systems in two regions in Kenya. Stover applied at 4 tonnes DM/ha was found to have highly variable effects on maize growth and yield according to site., method of stover placement, N application and season. Relative to controls without stover, stover incorporation reduced yield by 39% in the first season, followed by yield increases of 15% in the second season. In the first season there was little or no response to N in the presence of stover. Low N uptake and N use efficiency suggested N immobilization in the incorporation treatment. Yield responses and large N uptake in the following season suggested mineralization of N immobilized in the previous season. Surface mulching at the Kabete site increased grain yields in the first season by 39% and 6% compared to stover removal without and with fertilizer, resp. In the second season, surface mulching markedly reduced yields possibly due to a combination of reduced phytotoxicity and N immobilization. At the Katumani site, stover amendments increased yields compared to removal in both seasons with incorporation results being superior to surface mulch. At this site, in both seasons, application of N reduced the effect of stover mulching and incorporation. You must log in to CAB Direct in order to view search results. If you have forgotten your log

Stover placement (surface mulch, incorporated or a mixture of mulch and incorporation) was compared with stover removal in the presence and absence of 50kg N fertilizer/ha in trials over two successive seasons in continuous maize cropping systems in two regions in Kenya. Stover applied at 4 tonnes DM/ha was found to have highly variable effects on maize growth and yield according to site., method of stover placement, N application and season. Relative to controls without stover, stover incorporation reduced yield by 39% in the first season, followed by yield increases of 15% in the second season. In the first season there was little or no response to N in the presence of stover. Low N uptake and N use efficiency suggested N immobilization in the incorporation treatment. Yield responses and large N uptake in the following season suggested mineralization of N immobilized in the previous season. Surface mulching at the Kabete site increased grain yields in the first season by 39% and 6% compared to stover removal without and with fertilizer, resp. In the second season, surface mulching markedly reduced yields possibly due to a combination of reduced phytotoxicity and N immobilization. At the Katumani site, stover amendments increased yields compared to removal in both seasons with incorporation results being superior to surface mulch. At this site, in both seasons, application of N reduced the effect of stover mulching and incorporation. You must log in to CAB Direct in order to view search results. If you have forgotten your log

Long-term use of compost (4, 8, 12 or 125 kg/ha for maize and 10, 20, 30 or 200 kg/ha for beans) on improving crop yields and soil physical characteristics was studied at the steep-land research site, Kabete campus, Kenya. Preliminary results showed that maize yields under compost were lower than under diammonium phosphate (DAP). Compost increased the maize yield by 15% compared to an increase of 50% caused by DAP. Bean yield did not show any response to any rates of compost or DAP. The use of compost improved soil physical conditions, mainly bulk density and infiltration rates.

Long-term use of compost (4, 8, 12 or 125 kg/ha for maize and 10, 20, 30 or 200 kg/ha for beans) on improving crop yields and soil physical characteristics was studied at the steep-land research site, Kabete campus, Kenya. Preliminary results showed that maize yields under compost were lower than under diammonium phosphate (DAP). Compost increased the maize yield by 15% compared to an increase of 50% caused by DAP. Bean yield did not show any response to any rates of compost or DAP. The use of compost improved soil physical conditions, mainly bulk density and infiltration rates

The effectiveness of different grass spp. in reducing runoff and soil loss was studied at Kabete campus, University of Nairobi, Kenya. Half metre wide strips of Napier grass (Pennisetum purpureum), Nandi setaria (Setaria anceps) and tall Signal grass (Brachiaria ruziziensis) were established on 11m x 2m runoff plots, and runoff and soil loss were monitored for each rainfall event during the long and short rains of 1990. In terms of runoff control, there was no significant difference between treatments during early establishment; however, runoff form plot with filter strips was always lower than controls. B. ruziziensis was most effective at runoff and soil loss reduction and this was attributed to growth habit and slow rate of establishment. The capability of the strips to impede runoff improved with time.

The effectiveness of different grass spp. in reducing runoff and soil loss was studied at Kabete campus, University of Nairobi, Kenya. Half metre wide strips of Napier grass (Pennisetum purpureum), Nandi setaria (Setaria anceps) and tall Signal grass (Brachiaria ruziziensis) were established on 11m x 2m runoff plots, and runoff and soil loss were monitored for each rainfall event during the long and short rains of 1990. In terms of runoff control, there was no significant difference between treatments during early establishment; however, runoff form plot with filter strips was always lower than controls. B. ruziziensis was most effective at runoff and soil loss reduction and this was attributed to growth habit and slow rate of establishment. The capability of the strips to impede runoff improved with time.

The effects of P supply (0, 20, 40, 80, 160 and 320 kg/ha) on growth and nodulation of cowpeas (Vigna unguiculata) cv. Vita 4 and Ife Brown grown in a podzolic soil (Haplustult) was studied in a greenhouse trial. The seeds were inoculated with Bradyrhyzobium CB 756. Plants were harvested at the beginning of flowering. The number of trifoliate leaves and DM yield in both cv. increased with increasing P application. The yield of the tops of Vita 4 was maximum at 160 kg P/ha and that of Ife Brown at 320 kg P/Ha. Extractable P related linearly to the rate of applied P, and DM yield increased with increase in extractable P. Plants grown without P had fewer and smaller nodules. An increase in P from 1 to 160 kg/ha increased the number of nodules/plant from 16 to 113 in Vita 4 and from 14 to 70 in Ife Brown. Similarly, increasing P increased nodule dry weight. The P conc. of the youngest fully expanded leaf (YFEL) and in the whole plant top increased with increasing P supply in both cv. and was generally higher in the YFEL than in the whole top. A critical P conc. of 0.3 and 0.25% was found in the YFEL and the whole top, resp., for cv. Vita 4.

The effects of P supply (0, 20, 40, 80, 160 and 320 kg/ha) on growth and nodulation of cowpeas (Vigna unguiculata) cv. Vita 4 and Ife Brown grown in a podzolic soil (Haplustult) was studied in a greenhouse trial. The seeds were inoculated with Bradyrhyzobium CB 756. Plants were harvested at the beginning of flowering. The number of trifoliate leaves and DM yield in both cv. increased with increasing P application. The yield of the tops of Vita 4 was maximum at 160 kg P/ha and that of Ife Brown at 320 kg P/Ha. Extractable P related linearly to the rate of applied P, and DM yield increased with increase in extractable P. Plants grown without P had fewer and smaller nodules. An increase in P from 1 to 160 kg/ha increased the number of nodules/plant from 16 to 113 in Vita 4 and from 14 to 70 in Ife Brown. Similarly, increasing P increased nodule dry weight. The P conc. of the youngest fully expanded leaf (YFEL) and in the whole plant top increased with increasing P supply in both cv. and was generally higher in the YFEL than in the whole top. A critical P conc. of 0.3 and 0.25% was found in the YFEL and the whole top, resp., for cv. Vita 4.

This paper examines the impact of sand harvesting from rivers on the environment, land use and social life in the Masinga Division, Machakos District, Kenya. Sand acts as a safe aquifer for water flowing below and through it. Removal of sand results in destruction of underground aquifers and loss of safe water. sand scooping adversely affects surface water quality and quantity and damages the aquatic ecosystem. Haulage of sand by heavy trucks causes environmental degradation by accelerating soil erosion and affecting soil stability. Storage of sand causes destruction of surface areas through clearing of vegetation and uses land that could be used for agriculture. Related social and health problems include prostitution and high school drop-out rate leading to serious social and health problems. The beneficial effects of sand harvesting include local employment; however, the share of monetary benefits to locals is minimal. The results show that the local community gains the least from sand harvesting, but stands to suffer the most if the degradation of the river system continues. Suggestions are made for safe and sustainable methods of managing sand harvesting, in which greater local involvement and stricter enforcement of regulations to protect the environment are vital.

This paper examines the impact of sand harvesting from rivers on the environment, land use and social life in the Masinga Division, Machakos District, Kenya. Sand acts as a safe aquifer for water flowing below and through it. Removal of sand results in destruction of underground aquifers and loss of safe water. sand scooping adversely affects surface water quality and quantity and damages the aquatic ecosystem. Haulage of sand by heavy trucks causes environmental degradation by accelerating soil erosion and affecting soil stability. Storage of sand causes destruction of surface areas through clearing of vegetation and uses land that could be used for agriculture. Related social and health problems include prostitution and high school drop-out rate leading to serious social and health problems. The beneficial effects of sand harvesting include local employment; however, the share of monetary benefits to locals is minimal. The results show that the local community gains the least from sand harvesting, but stands to suffer the most if the degradation of the river system continues. Suggestions are made for safe and sustainable methods of managing sand harvesting, in which greater local involvement and stricter enforcement of regulations to protect the environment are vital.

The possible environmental impacts of water development projects and land use practices such as deforestation and over grazing on water supply in Kenya are reviewed. Measures that can be taken in conjunction with properly conducted environmental impact assessments to mitigate adverse impacts are suggested

The possible environmental impacts of water development projects and land use practices such as deforestation and over grazing on water supply in Kenya are reviewed. Measures that can be taken in conjunction with properly conducted environmental impact assessments to mitigate adverse impacts are suggested

This paper describes earthflow features in Nyairoko sub-location of Ol Joro Orok Division, Kenya. In 1989 more than 900 earthflows were counted in Nyandarua District, most of them in Ol Joro Orok and Ol Kalou Divisions. Individual flows affected areas between a few square metres and two hectares. More than 50% of the farms in the area were affected by earthflows. Such earthflows occurred only on grazing land and on convex slopes and were usually the result of extremely slow processes. Soils in the area are mainly moderately well drained, dark reddish brown Luvisols and well-drained, red to reddish-brown Nitisols. The first visible signs were usually shallow scars along the contour, breaking up the grass vegetation. Subsequent soil movement was very gradual. According to old residents of the area some of the earthflow features had been observed as long as 60 years ago and could not be attributed to land use change. One earthflow studied in detail revealed that soil stratification impeded drainage, leading to oversaturation of the topsoil layers and that seasonal subsurface flow generally seemed to be responsible for the soil movement. No obvious triggering could be identified.

This paper describes earthflow features in Nyairoko sub-location of Ol Joro Orok Division, Kenya. In 1989 more than 900 earthflows were counted in Nyandarua District, most of them in Ol Joro Orok and Ol Kalou Divisions. Individual flows affected areas between a few square metres and two hectares. More than 50% of the farms in the area were affected by earthflows. Such earthflows occurred only on grazing land and on convex slopes and were usually the result of extremely slow processes. Soils in the area are mainly moderately well drained, dark reddish brown Luvisols and well-drained, red to reddish-brown Nitisols. The first visible signs were usually shallow scars along the contour, breaking up the grass vegetation. Subsequent soil movement was very gradual. According to old residents of the area some of the earthflow features had been observed as long as 60 years ago and could not be attributed to land use change. One earthflow studied in detail revealed that soil stratification impeded drainage, leading to oversaturation of the topsoil layers and that seasonal subsurface flow generally seemed to be responsible for the soil movement. No obvious triggering could be identified.

Forty controlled gullies distributed in Kiambu, Murang'a and Nyeri Districts of Central Province, Kenya, were randomly selected to evaluate their control measures. A recording schedule was developed to assist in collecting pertinent information. Results indicate that the failure of gully control in Central Province can be attributed to lack of technically skilled personnel and poor maintenance of gully control structures. It is concluded that there is a great need to impart technical knowledge to technical staff, and that it is essential to intensify research on gully control techniques and that there is regular and proper maintenance of all gully control structures after rainstorms.

Forty controlled gullies distributed in Kiambu, Murang'a and Nyeri Districts of Central Province, Kenya, were randomly selected to evaluate their control measures. A recording schedule was developed to assist in collecting pertinent information. Results indicate that the failure of gully control in Central Province can be attributed to lack of technically skilled personnel and poor maintenance of gully control structures. It is concluded that there is a great need to impart technical knowledge to technical staff, and that it is essential to intensify research on gully control techniques and that there is regular and proper maintenance of all gully control structures after rainstorms.

This paper looks at factors which influence land allocation and crop production patterns in Botswana, across traditional and commercial farmers. It found that, among smallholder traditional farmers, less land is used (on average 5.6 ha) and is subdivided into the growing of three major crops: sorghum, maize and beans, with more land allocated to sorghum, the main staple and more adaptable to the climate. The small amount of cultivated land is attributed to lack of capital, transport and labour. Although large areas of land are owned by commercial farmers a high percentage is left idle due to constraints such as poor marketing systems, poor storage facilities and shortage of labour.

This paper looks at factors which influence land allocation and crop production patterns in Botswana, across traditional and commercial farmers. It found that, among smallholder traditional farmers, less land is used (on average 5.6 ha) and is subdivided into the growing of three major crops: sorghum, maize and beans, with more land allocated to sorghum, the main staple and more adaptable to the climate. The small amount of cultivated land is attributed to lack of capital, transport and labour. Although large areas of land are owned by commercial farmers a high percentage is left idle due to constraints such as poor marketing systems, poor storage facilities and shortage of labour

Runoff and soil loss was studied on steep terraced slopes containing various combinations of lines of Grevillea robusta, hedgerows of Calliandra calothyrsus and strips of Pennisetum purpureum in Kabale, southwest Uganda. A factorial design, replicated three times, included three levels of intra-row spacing (0, 3 and 5m) of Grevillea spp. and three understorey types (none, Pennisetum and Calliandra spp). The understorey and Grevillea were interplanted along a contour in the middle of the terrace parallel to the two adjacent risers. Results indicate that when contour lines of trees are on fallow ground there is little or possibly a negative effect in controlling soil and water loss. When contour lines are on steep cultivated terraces they have a significant effect in reducing losses. The understoreys appear to filter out much of the sediment from the runoff, holding it in or above the contour line of the vegetation. The potential for using contour lines of Pennisetum and Calliandra for controlling soil and water loss is discussed.

Runoff and soil loss was studied on steep terraced slopes containing various combinations of lines of Grevillea robusta, hedgerows of Calliandra calothyrsus and strips of Pennisetum purpureum in Kabale, southwest Uganda. A factorial design, replicated three times, included three levels of intra-row spacing (0, 3 and 5m) of Grevillea spp. and three understorey types (none, Pennisetum and Calliandra spp). The understorey and Grevillea were interplanted along a contour in the middle of the terrace parallel to the two adjacent risers. Results indicate that when contour lines of trees are on fallow ground there is little or possibly a negative effect in controlling soil and water loss. When contour lines are on steep cultivated terraces they have a significant effect in reducing losses. The understoreys appear to filter out much of the sediment from the runoff, holding it in or above the contour line of the vegetation. The potential for using contour lines of Pennisetum and Calliandra for controlling soil and water loss is discussed.

The implications of global climatic change on water resource development and management in Kenya was examined. The extent to which the water resources of the various regions of Kenya will be affected and the effects on streamflow regimes, rainfall amount, frequency and distribution patterns and the overall effects of these on socio-economic development are discussed. It is suggested that increased drought could occur in low-potential regions of Eastern, Rift valley and North Eastern Provinces, whilst regions that already receive a favourable amount of rainfall could have even higher amounts. Changes in rainfall patterns and stream discharge may require translocation of current water development projects with possible high costs and dire consequences for those dependent upon such projects. The increases aridity in the arid and semi-arid lands may lead to increased salinity of groundwater, limiting it's use. Recommendations include water conservation strategies, groundwater basin recharge, inter-basin water transfer from high to low potential zones, cloud seeding above arid and semi-arid areas, better soil and water conservation strategies, and controlling the use of products contributing to global warming.

The implications of global climatic change on water resource development and management in Kenya was examined. The extent to which the water resources of the various regions of Kenya will be affected and the effects on streamflow regimes, rainfall amount, frequency and distribution patterns and the overall effects of these on socio-economic development are discussed. It is suggested that increased drought could occur in low-potential regions of Eastern, Rift valley and North Eastern Provinces, whilst regions that already receive a favourable amount of rainfall could have even higher amounts. Changes in rainfall patterns and stream discharge may require translocation of current water development projects with possible high costs and dire consequences for those dependent upon such projects. The increases aridity in the arid and semi-arid lands may lead to increased salinity of groundwater, limiting it's use. Recommendations include water conservation strategies, groundwater basin recharge, inter-basin water transfer from high to low potential zones, cloud seeding above arid and semi-arid areas, better soil and water conservation strategies, and controlling the use of products contributing to global warming.

Trends in land use practices in the Lake Nakuru catchment area and, in particular, the causes and impacts of deforestation, which threaten the lake's unique ecology. It addresses the importance of natural forests for the successful management of the lake's watershed area. Findings are all discussed in the broader, national context and some suggestions for programmes of action to alleviate problems caused by deforestation are presented.

Trends in land use practices in the Lake Nakuru catchment area and, in particular, the causes and impacts of deforestation, which threaten the lake's unique ecology. It addresses the importance of natural forests for the successful management of the lake's watershed area. Findings are all discussed in the broader, national context and some suggestions for programmes of action to alleviate problems caused by deforestation are presented.

The effect of wind erosion in areas subjected to continuous pastoral use compared with the effects of rangeland rehabilitation in areas subjected to natural recovery were studied at four sites in eco-climate zone VI in the Marsabit District of Kenya. The study was conducted using erosion pins and comparing organic and soil texture changes within the first 10cm of the soil. The soils ranged from loamy sand in the rehabilitation enclosure to sandy soils in the area with continual use. In all cases the soils had poor aggregate stability. An average annual soil loss of 95t/ha was observed in the areas under continuous use where vegetation was minimal, whilst soil was deposited at a rate of 446t/ha annually in the rehabilitation enclosure in which there was plentiful Indigofera dwarf shrubland vegetation

A model of the Ndarugu riverbank intake, Kenya, was used to test various possibilities of weir construction. It was found that by narrowing the river near the intake to increase velocity, sedimentation was drastically reduced. This solution was found to be economically feasible and easy to implement.

The constraints on land use and water resources for sustainable agricultural production in Kenya were assessed during May to September 1992 using questionnaires and personal interviews along with existing secondary data using districts representative of the country as a whole. It is concluded that land use planning in Kenya is disastrous. A large proportion of good land is under commercial crops that are less important than food crops, from social and political standpoints. Soil degradative processes, other than accelerated erosion, should be given due attention. Erosion control measures should be evaluated for technical feasibility, economic benefit, social acceptability and environmental suitability. Soil erosion classification is required. Drainage and irrigation potentials are under-exploited, whilst fertilizer use on food crops is minimal. Due to maldistribution and mismanagement of land and water resources, low crop production per unit of land is common. It is recommended that techniques be developed to ensure sustained high productivity of land to satisfy changing needs without unnecessary opening up of new land

This paper is concerned with policy and development issues relating to the planning of rural land use in Kenya. The central theme of the analysis is the critical and urgent need for sustainable land use. Based on a study of land considerations in past development policies and of current land use issues, the paper discusses current development strategies and issues. Pitfalls likely to be encountered in future land use planning in rural Kenya are discussed.

A review of available literature on the hydrologic impacts of drainage is presented and management practices that reduce such impacts are identified. Factors that influence the impact of drainage include land use, soil type, drainage density, type and condition of the drains, size and duration of the storm, and extent and location of the drainage. Suggested options for minimising impacts include: appropriate land use (fish ponds, duck farming, harvesting natural products, dry season grazing or cultivation); controlled drainage through use of shallow drains, drainage for growing water-loving plants, land preparation (hilling, cambered beds), and blocking drains at the end of the rains; and water storage (dams along the river or farm ponds).

A review of available literature on the hydrologic impacts of drainage is presented and management practices that reduce such impacts are identified. Factors that influence the impact of drainage include land use, soil type, drainage density, type and condition of the drains, size and duration of the storm, and extent and location of the drainage. Suggested options for minimising impacts include: appropriate land use (fish ponds, duck farming, harvesting natural products, dry season grazing or cultivation); controlled drainage through use of shallow drains, drainage for growing water-loving plants, land preparation (hilling, cambered beds), and blocking drains at the end of the rains; and water storage (dams along the river or farm ponds).

During the last 40 years, water development in the southern Marsabit District of Kenya concentrated mainly on drilling boreholes and constructing large dams and pans which are difficult to maintain without financial aid. In order to make the nomads independent of outside aid, the Marsabit Development Programme has introduced animal traction for dam and pan construction and promotes the management of shallow wells. This paper reports the experiences encountered so far in the integration of water development within the natural resource improvement programme and discusses lessons learnt during the 1991/2 drought in the area in terms of water development and nomadic lifestyle.

During the last 40 years, water development in the southern Marsabit District of Kenya concentrated mainly on drilling boreholes and constructing large dams and pans which are difficult to maintain without financial aid. In order to make the nomads independent of outside aid, the Marsabit Development Programme has introduced animal traction for dam and pan construction and promotes the management of shallow wells. This paper reports the experiences encountered so far in the integration of water development within the natural resource improvement programme and discusses lessons learnt during the 1991/2 drought in the area in terms of water development and nomadic lifestyle

This paper briefly presents a methodology for planning development in arid and semi-arid areas. It highlights the issues of problem identification and assessment of the natural and socio-economic environment, and describes the database contained in the Range Management Handbook. The handbook makes available baseline data for planning development in arid and semi-arid areas following a successful Farm Management Handbook that covers the high- and medium-potential areas of Kenya. In three parts, the Range Management Handbook covers: the status, principles and applications in Kenya; texts and maps relating to climate, landforms and soils, vegetation types, water sources, range unit inventory, livestock marketing and human ecology; special reports (guide to tolerant plants, pictorial key for goat stocking rates, large scale remote monitoring of vegetation, and a survey method for classification of range conditions) relevant to land planning and use in arid and semi-arid areas

This paper briefly presents a methodology for planning development in arid and semi-arid areas. It highlights the issues of problem identification and assessment of the natural and socio-economic environment, and describes the database contained in the Range Management Handbook. The handbook makes available baseline data for planning development in arid and semi-arid areas following a successful Farm Management Handbook that covers the high- and medium-potential areas of Kenya. In three parts, the Range Management Handbook covers: the status, principles and applications in Kenya; texts and maps relating to climate, landforms and soils, vegetation types, water sources, range unit inventory, livestock marketing and human ecology; special reports (guide to tolerant plants, pictorial key for goat stocking rates, large scale remote monitoring of vegetation, and a survey method for classification of range conditions) relevant to land planning and use in arid and semi-arid areas

This paper presents results from a trial in Swara Farm, Njoro, Kenya, in which a field was sown with Sorghum almum on a volcanic ash soil. Immediately after sowing, 14 strips measuring 156 m x 9 m were marked out and alternate strips were oversown with inoculated seed of lucerne cv. Hairy Peruvian. During the first year of the trial no differences were noticed in the growth of S. almum, but during the second year it grew better when associated with lucerne. After two years the field was ploughed and sown with wheat. The strips were harvested separately with a combine harvester. Mean yields after S. almum were 2,708 kg/ha and after the S.almum/lucerne mixture were 3,244 kg/ha

This paper presents results from a trial in Swara Farm, Njoro, Kenya, in which a field was sown with Sorghum almum on a volcanic ash soil. Immediately after sowing, 14 strips measuring 156 m x 9 m were marked out and alternate strips were oversown with inoculated seed of lucerne cv. Hairy Peruvian. During the first year of the trial no differences were noticed in the growth of S. almum, but during the second year it grew better when associated with lucerne. After two years the field was ploughed and sown with wheat. The strips were harvested separately with a combine harvester. Mean yields after S. almum were 2,708 kg/ha and after the S.almum/lucerne mixture were 3,244 kg/ha.

This paper reflects on the role of root crops (cocoyam, Colocasia esculenta or C. antiquorum) as a case study in riverbank protection and food security in Kenya. Field performance, water erosion control, ecologically friendly production and food value were studied. It is concluded that the national relevance of cocoyam cultivation lies in its role in its conservation through erosion control and soil fertility maintenance; its low energy input; its potential to supplement per capita calories through high yield per unit area; its perpetuity; its multiple nutritive value, ease of preparation and digestibility; and its industrial potential and competitive market opportunity for various end-products.

This paper reflects on the role of root crops (cocoyam, Colocasia esculenta or C. antiquorum) as a case study in riverbank protection and food security in Kenya. Field performance, water erosion control, ecologically friendly production and food value were studied. It is concluded that the national relevance of cocoyam cultivation lies in its role in its conservation through erosion control and soil fertility maintenance; its low energy input; its potential to supplement per capita calories through high yield per unit area; its perpetuity; its multiple nutritive value, ease of preparation and digestibility; and its industrial potential and competitive market opportunity for various end-products.

This paper presents results of a study aimed at quantifying soil and water management practices and identifying major constraints and implications for future adoption of appropriate technologies. The study was conducted in the Machakos and Makueni Districts of Kenya. Approximately 83% of the farmers interviewed were using manure, while only 4% use fertilizer. 60% had fanya juu terraces on their land, while only 13% were using grass strips. The study concluded that finance is a major constraint limiting farmers' adoption of practices enhancing soil fertility and that lack of conservation practices on grazing land is of great concern. The lack of knowledge of possible benefits of soil and water management practices is noted.

This paper presents results of a study aimed at quantifying soil and water management practices and identifying major constraints and implications for future adoption of appropriate technologies. The study was conducted in the Machakos and Makueni Districts of Kenya. Approximately 83% of the farmers interviewed were using manure, while only 4% use fertilizer. 60% had fanya juu terraces on their land, while only 13% were using grass strips. The study concluded that finance is a major constraint limiting farmers' adoption of practices enhancing soil fertility and that lack of conservation practices on grazing land is of great concern. The lack of knowledge of possible benefits of soil and water management practices is noted.

The existing soil erosion damage caused by water drained from minor roads in the Nyeri District of Kenya was assessed and the soil conservation works needed to stabilize the waterways and gullies along the roads are specified. The study evaluated the land affected by road drains/culverts on 25 minor roads with a total length of 149 km. Of the total of 321 culverts identified, 171 (53%) were found to require channel rehabilitation. 68% of the culverts discharged onto steep slopes (>10%). Erosion was found to be more severe in the coffee-growing zones than in tea-growing areas. In the plateau areas, soil erosion from the culvert outlets was minimal. Due to gentle slopes and more perennial vegetation. 20,346 m of channel excavation was needed to provide artificial waterways for the discharge of water drained from the roads. Channel stabilization with grass cover or installation of scour checks was necessary on very gentle slopes. Steep slopes required stone check-dams and single-row post/stone check-dams. Very steep slopes also required lock-and-spill drains and post/stone/wire check-dams. Gabions (57 crossings) were needed mainly for rehabilitation of large gullies along with double-row post/stone check-dams and post/stone/wire check dams. Cut-off drains were necessary in some cases to divert water from the culvert outlets. In areas where vegetation was easily accessible, brushwood check-dams could be used.

The existing soil erosion damage caused by water drained from minor roads in the Nyeri District of Kenya was assessed and the soil conservation works needed to stabilize the waterways and gullies along the roads are specified. The study evaluated the land affected by road drains/culverts on 25 minor roads with a total length of 149 km. Of the total of 321 culverts identified, 171 (53%) were found to require channel rehabilitation. 68% of the culverts discharged onto steep slopes (>10%). Erosion was found to be more severe in the coffee-growing zones than in tea-growing areas. In the plateau areas, soil erosion from the culvert outlets was minimal. Due to gentle slopes and more perennial vegetation. 20,346 m of channel excavation was needed to provide artificial waterways for the discharge of water drained from the roads. Channel stabilization with grass cover or installation of scour checks was necessary on very gentle slopes. Steep slopes required stone check-dams and single-row post/stone check-dams. Very steep slopes also required lock-and-spill drains and post/stone/wire check-dams. Gabions (57 crossings) were needed mainly for rehabilitation of large gullies along with double-row post/stone check-dams and post/stone/wire check dams. Cut-off drains were necessary in some cases to divert water from the culvert outlets. In areas where vegetation was easily accessible, brushwood check-dams could be used.

This paper examines the anomalies in the sedimentation rating equations in terms of existing notions of statistical analysis and concludes that c=aqb is the preferred relationship. The method of estimating parameters a and b through ordinary least squares and the method of prediction using the log normal probability distribution of the error component z (c=aqbz) is presented using data for the Mathare river at Kabete, Kenya. The need for nonlinear least squares for estimation of parameters a and b is discussed in relation to the additive nature of the error component (c=aqb + z) n the nonlinear form of rating equation. The equation c=Faqb (where F is a correction factor arising due to log normal distribution of the error term z) predicted the sediment yield of the Mathare catchment quite well for 61 days during the long rainy season of 1991.

This paper examines the anomalies in the sedimentation rating equations in terms of existing notions of statistical analysis and concludes that c=aqb is the preferred relationship. The method of estimating parameters a and b through ordinary least squares and the method of prediction using the log normal probability distribution of the error component z (c=aqbz) is presented using data for the Mathare river at Kabete, Kenya. The need for nonlinear least squares for estimation of parameters a and b is discussed in relation to the additive nature of the error component (c=aqb + z) n the nonlinear form of rating equation. The equation c=Faqb (where F is a correction factor arising due to log normal distribution of the error term z) predicted the sediment yield of the Mathare catchment quite well for 61 days during the long rainy season of 1991.

This paper describes a "near-farmer" applied research project working on 10 field stations scattered through the arid and semi-arid lands of Embu, Meru and Isiolo Districts of Esatern Province, Kenya. The objective of the research was to define better extension messages for resource-poor farmers to enable them to improve their land and water management techniques for improved and sustained yields. Most of the trials related to soil fertility and soil moisture, as well as trials on the use of Vetiver grass for soil conservation, control of the legume root parasite Alectra vogelii, and new introductions such as groundnuts, simsim (sesame), tubers, fodder crops and fruits.

This paper describes a "near-farmer" applied research project working on 10 field stations scattered through the arid and semi-arid lands of Embu, Meru and Isiolo Districts of Esatern Province, Kenya. The objective of the research was to define better extension messages for resource-poor farmers to enable them to improve their land and water management techniques for improved and sustained yields. Most of the trials related to soil fertility and soil moisture, as well as trials on the use of Vetiver grass for soil conservation, control of the legume root parasite Alectra vogelii, and new introductions such as groundnuts, simsim (sesame), tubers, fodder crops and fruits.

This paper examines some of the reasons for the low success rate in gully control and argues that a more careful examination of each situation and a greater understanding of the processes at work could lead to more successful interventions. It outlines a systematic evaluation of a gully erosion problem and analysis of the options for control or reclamation. Evaluation should involve assessment of the causes of gully formation, gully morphology, gully erosion/sedimentation processes, soil characteristics, land use in the vicinity, and catchment characteristics.

Initial observations of a two-phase trial on the use of Mucuna deeringianum [M. deeringiana] to improve soil productivity are presented. In phase one, 42 seeds were sown at Kabete, Kenya, in October 1990 with 89% germination rate. By September 1991, 4 kg of beans had been harvested. The second phase studied the effects of M. deeringiana on improving crop cover and reducing soil loss at Mbooni and Kabete, resp. Initial observations show that the crop preformed fairly well, providing a cover of up to 25cm uncompressed thickness. Treatments on the runoff plots at Kabete include: bare ground (control), M. deeringiana; maize; the two crops intercropped and sown at the same time; intercropping with M. deeringiana sown one week after the maize; or intercropped with M. deeringiana sown two weeks after the maize. The highest soil loss was found on the bare plot (65 t/ha), followed by the intercropped plot with two weeks between sowing (50 t/ha). Soil loss was lowest in runoff plots with a pure stand of M. deeringiana (11 t/ha). Intercropping and sown at the same time provided highest percentage cover.

The results of soil surveys at the ICIPE research site at Ungoye, South Nyanza, and the Ngori Ngori toposequence in Narok, Kenya, are discussed to provide insight into the applicability of soil survey information to soil and water management. It is concluded that soil survey information in soil and water management programmes can be used through understanding and appreciation of the criteria used in categorizing soils and their management implications. From the examples given it is noted that chemical aspects of the soil should be viewed not just as a means to assess its fertility, but also as a base to predict the behaviour of the soils when subjected to different types of management.

The results of soil surveys at the ICIPE research site at Ungoye, South Nyanza, and the Ngori Ngori toposequence in Narok, Kenya, are discussed to provide insight into the applicability of soil survey information to soil and water management. It is concluded that soil survey information in soil and water management programmes can be used through understanding and appreciation of the criteria used in categorizing soils and their management implications. From the examples given it is noted that chemical aspects of the soil should be viewed not just as a means to assess its fertility, but also as a base to predict the behaviour of the soils when subjected to different types of management.

This report presents results of measurements of sound levels, chemical analysis of air particulate matter and soil samples from two factories in Nairobi. A preliminary assessment of suspended particulate matter (SPM) in a residential site and its possible impacts on acute …

ENVIRONMENTAL AND INDUSTRIAL APPLICATIONS OF XRF AND RELATED TECHNIQUES AT THE INSTITUTE OF NUCLEAR SCIENCE, UNIVERSITY OF NAIROBI, KENYA AM KJNYUA1, CK GATEBE1, MJ MANGALA1, XA9953279" DM MAINA1, AK KORIR1, K …

Air pollution studies in Nairobi are indicating a rising trend in the particulate matter loading. The trend is mainly attributed to increased volume of motor vehicles, the physical change of the environment, agricultural and industrial activities. In this study, total suspended …

A stream flow model was developed for use in rural catchments in Kenya. In the model the physical environment was divided into three zones: the unsaturated zone (consists of multiple hydrological response units defined by homogenous land use and soil type in which a daily soil moisture balance is maintained), shallow saturated and deep saturated zones which were modelled as regional aquifers. Rainfall and evapotranspiration were distributed according to altitude, and runoff was determined using the curve number method devised by the US Soil Conservation Service: a function of five-day antecedent precipitation. Evapotranspiration was varied according to the soil moisture content, and the weather generator allowed Monte Carol simulations over a long period. The data consisted of daily rainfall, mean daily evaporation for each month, land use/vegetation and soil type. The ARC-INFO GIS package was used to assemble the topographical, hydrological, land use/vegetation type and soil information in different layer. The model was tested on the Naro Moru catchment (172kn2) in Kenya, which has climatic conditions that vary from the glaciated peaks of Mount Kenya (5,200 m) to the semi-arid Laikipia plateau (1,800 m). The model was calibrated over a two-year period and validated over a different two-year period. A comparison of the observed and simulated stream flow showed that minimal calibration was required. The simulated stream flow compared well with the observed values for both the calibration and the validation periods (70-85% for the 10-day period) indicating that the model is appropriate for ungauged catchments.

A stream flow model was developed for use in rural catchments in Kenya. In the model the physical environment was divided into three zones: the unsaturated zone (consists of multiple hydrological response units defined by homogenous land use and soil type in which a daily soil moisture balance is maintained), shallow saturated and deep saturated zones which were modelled as regional aquifers. Rainfall and evapotranspiration were distributed according to altitude, and runoff was determined using the curve number method devised by the US Soil Conservation Service: a function of five-day antecedent precipitation. Evapotranspiration was varied according to the soil moisture content, and the weather generator allowed Monte Carol simulations over a long period. The data consisted of daily rainfall, mean daily evaporation for each month, land use/vegetation and soil type. The ARC-INFO GIS package was used to assemble the topographical, hydrological, land use/vegetation type and soil information in different layer. The model was tested on the Naro Moru catchment (172kn2) in Kenya, which has climatic conditions that vary from the glaciated peaks of Mount Kenya (5,200 m) to the semi-arid Laikipia plateau (1,800 m). The model was calibrated over a two-year period and validated over a different two-year period. A comparison of the observed and simulated stream flow showed that minimal calibration was required. The simulated stream flow compared well with the observed values for both the calibration and the validation periods (70-85% for the 10-day period) indicating that the model is appropriate for ungauged catchments.

This paper examine past and present trends in the development of Kenyan water resources, and the status of Kenya's arid and semi-arid lands. It considers the parameters linked with soil erosion and sedimentation processes and suggests means of combating the problem.

This paper examine past and present trends in the development of Kenyan water resources, and the status of Kenya's arid and semi-arid lands. It considers the parameters linked with soil erosion and sedimentation processes and suggests means of combating the problem.