Agricultural Engineering

The Mara River Basin (MRB) is one of the catchment of the Lake Victoria covering a drainage area of 13,750km2 and form part of the Upper Nile Basin. The Mara River (MR) supply water into the Lake Victoria throughout the year. In the recent years, the basin has undergone tremendous changes and long term monitoring also identified several areas of concern in the upper catchment of the basin. The aim of this study was to develop a framework of rainfall-runoff model application in poorly gauged Basin by integrating with Remote Sensing, GIS and satellite derived dataset. Hydrological modelling is necessary tool for water resource and policy analysis. However studying the complexity of hydrological process and modelling in such catchments is one of challenging area of hydrology.
This study explored the potential of Hydrologic Engineering Centre-Hydrologic Modelling System (HEC-HMS 3.5) in conjunction HEC-GeoHMS extension in ArcMap 9.3 or ArcView as a tool for water management in upper catchment, Mara River Basin. GIS layers that were needed as input data were prepared using ArcMap 9.3. HEC-HMS is a semi-distributed model which focuses on rainfall-runoff processes and simulation were applied on a daily scale. The model was calibrated and validated using the 2005 and 2006 data set respectively. The evaluation of the model was tested statistically employing the correlation coefficient (R2), Relative Error (RE), and Nash-Sutcliffe Efficiency Index (EI). The R2 for Nyangores and Amala during calibration and (validation) were 0.53 (0.41) and 0.21 (0.24) respectively where else the EI during calibration and (validation) were 0.93 (0.91) and 17.10 (0.46) for Nyangores and Amala respectively. The model shows great potential in simulating the wet season runoff. The application of HEC-HMS model is considered to be satisfactory for Nyangores sub-catchment but further research is needs to be undertaken to access the results of Amala sub-catchment.
(Key words: Hydrological modelling, HEC-HMS, GIS, MRB, Nash-sutcliffe, rainfall, runoff)

Variability of streamflow has far-reaching impacts especially in developing countries. This is aggravated by climate change which has adversely affected the water resources and food security. This paper presents the characterization trends in extreme streamflow regimes with a view to providing information for planning local coping mechanisms to climate variability and change using streamflow data recorded from 1959 to 2008 in the Lake Naivasha basin in Kenya. The maxima and percentiles of streamflow distributions were investigated to identify changes in extreme intensity and frequency, respectively, using the Mann -Kendall test. The results indicate significant increases in annual maxima at all gauging stations. The flows in the month of November increased significantly at gauging stations 2GB4 and 2GC4. Flow percentile exceedance revealed that the annual 95th percentile exceedance increased significantly at gauging stations 2GB1 and 2GB5 with a decrease in annual 90th and 97th percentile exceedance at gauging stations 2GB4 and 2GC4. The results presented in this paper are useful for climate change adaptation planning and management especially in water supply, hydropower generation and agriculture.

The main parameters of drought phenomenon are the longest duration and largest severity for a desired return period. These parameters form the basis for designing water storage structures to cope with drought effects. In this study, these drought parameters were estimated using the probability based theory. The sample estimates of the mean, coefficient of variation, skew-ness, correlation and information on the probability distribution of flow sequence, were used as the basic input parameters. The truncation level was considered at mean level of the annual flow sequences of River Malewa in Lake Naivasha basin. In this basin, 100, 50, 10, 5 and 2-year droughts may persist continuously for 6, 4, 3, 2 and 1 years respectively. From the probabilistic approach for a normal probability distribution function, high values of coefficient of variation resulted in high values of the actual severity. The results show that there is drought severity in Lake Naivasha basin especially in parts experiencing high inter-annual variability in annual flow regimes.

Variability of streamflow has far-reaching impacts especially in developing countries. This is aggravated by climate change which has adversely affected the water resources and food security. This paper presents the characterization trends in extreme streamflow regimes with a view to providing information for planning local coping mechanisms to climate variability and change using streamflow data recorded from 1959 to 2008 in the Lake Naivasha basin in Kenya. The maxima and percentiles of streamflow distributions were investigated to identify changes in extreme intensity and frequency, respectively, using the Mann-Kendall test. The results indicate significant increases in annual maxima at all gauging stations. The flows in the month of November increased significantly at gauging stations 2GB4 and 2GC4. Flow percentile exceedance revealed that the annual 95th percentile exceedance increased significantly at gauging stations 2GB1 and 2GB5 with a decrease in annual 90th and 97th percentile exceedance at gauging stations 2GB4 and 2GC4. The results presented in this paper are useful for climate change adaptation planning and management especially in water supply, hydropower generation and agriculture.

The main parameters of drought phenomenon are the longest duration and largest severity for a desired return period. These parameters form the basis for designing water storage structures to cope with drought effects. In this study, these drought parameters were estimated using the probability based theory. The sample estimates of the mean, coefficient of variation, skewness, correlation and information on the probability distribution of flow sequence, were used as the basic input parameters. The truncation level was considered at mean level of the annual flow sequences of River Malewa in Lake Naivasha basin. In this basin, 100, 50, 10, 5 and 2-year droughts may persist continuously for 6, 4, 3, 2 and 1 years respectively. From the probabilistic approach for a normal probability distribution function, high values of coefficient of variation resulted in high values of the actual severity. The results show that there is drought severity in Lake Naivasha basin especially in parts exper...

A concise and factual abstract is required. The abstract should state briefly the purpose of the research, the principal results and major conclusions. It should not exceed 250 words. An abstract is often presented separately from the article, so it must be able to stand alone. For this reason, References should be avoided, but if essential, then cite the author(s) and year(s). Also, non-standard or uncommon abbreviations should be avoided, but if essential they must be defined at their first mention in the abstract itself.

The study was undertaken to determine site specific physical properties of soil in the plains of Eastern Mau Escarpment for the purposes of enhancing agricultural productivity. Soil physical characteristics are a function of soil moisture retention which has an important influence on agricultural productivity. Topography was found to be 1-1.65%. The soil profile of the mollic andosols was defined as; well drained, moderately deep with varied structure across the profile as supported by the trend of moisture content analysis down the profile which revealed that the moisture content variation was a third order quadratic function that increased with depth. It is characterized by coarse texture, low organic matter status, deep and well-drained profiles. The sieve analysis revealed that it is a rich gradation which refers to a sample of aggregate with a high proportion of particles of small sizes. The weighted means of soil fractions were 82.1, 2.7 and 15.2% for sand, silt and clay respectively. Bulk density, (BD), varied from 1.04-1.37 gcm -3 within the top soil. The highest BD in the study profiles was found to occur between 20 and 40cm depths, suggesting the existence of a plough pan. Particle density ranged from 1.61 to 2.18gcm -3 . Mean particle density was 2gcm -3 with high density particles dominating the top 20cm. The pF curves for samples from soil depths; 10, 20, 30, 40, 50 and 60 cm had unique SWCC though the soil texture was found to be similar in all sampled profiles. It was revealed that the plough pan layer retained more moisture than above and below it.

There has been low crop yield in Arid and Semi-Arid Lands (ASAL) of Sub Saharan Africa (SSA). In Kenya, lower Narok is one such area, where annual rainfall is enough to sustain wheat production, however, its distribution and intensity adversely affect crop yield since only 250-300mm occur during the long season from February to May and 100-200mm falls during short rains of October to December. The amount is not adequate for a full wheat crop development. The high rainfall intensity has lead to soil erosion, consequently to loss of soil fertility that has caused yield to plummet. Land terrain in addition to pastoral lifestyle of the local community, offer a challenge to young fertile soils with low soil water aggregation stability. Therefore the main objective of the project was to mitigate against the adverse effects of soil erosion and loss of water through construction of soil and water conservation structures and re-forestation. This was accomplished by analyzing long term rainfall data covering over 10 years to establish sowing dates, construction of level terraces at safe vertical heights and establishing local friendly vegetation on the ridges. Data was collected on the on moisture retained and crop rate of growth and yield within the ridges of the terrace. Four sites were selected and subjected to terrace treatment.

To increase efficiency in agricultural production among small scale farmers, mechanization was found to be the main driving tool. When all the mechanization aspects were ranked through a survey, seed processing and harvesting were found to be the most crucial areas of need hence the decision to fabricate the small grains seed dresser machine. Two prototypes, one electrically and another gasoline operated seed dressers (KARI Seed Dresser) were fabricated and tested for efficiencies. They are still undergoing testing at KARI Njoro, KARI Mwea, KARI Kibos and farmers fields. Results have shown that the dresser of 50kg capacity can uniformly dress small grains in 40 seconds, employs only two people, self offloading, and low maintenance. The electrically powered seed dresser loading was found to be 35Kg and the gasoline one was 50Kg.

The region around Lake Baringo is inhabited by semi-nomadic pastoralists of the Njemps Tugen, Turkana and Pokot ethnic groups which mainly depend on livestock for their livelihood (Kaimba et al.,2011). However, some crop production takes place. Rainfall is erratic with an average of about 650mm/year. The main rainy season starts from March to June. This study was conceived with the idea of demonstrating various soil and water conservation for crop development techniques which could be of value in combating desertification and improving the economic base of the population of this semi-arid region. Being on the lower side of Kamasia hills, it is also faced by floods due to runoff and backflow from Lake Baringo as the lake has no outlet.

Most biogas plants’ poor performance may be attributed to inadequate stirring strategy. The study evaluated the effect of stirring intervals on biogas production from cow dung and maize silage mixture (at mixed ratio 3:1) digested in a 0.15m3 laboratory digester at 30℃. SIEMENS LOGO PLC and ATV12HU15M2 Drive automatically controlled the stirring of 100 rpm for 3minutes at intervals of 1hour, 2hours, 6hours and 12hours with no stirring as control. The stirring intervals showed a significant effect on biogas production (P≤0.05) with 6hours and 12hours increased biogas by 3.11% and 1.48%, and the methane increase of 8.77% and 1.75%, respectively. The 2hours and 1hour reduced biogas by 26.5% and 39.35%, and methane decreased by 3.52% and 15.79%, respectively compared to control (implying that the frequent stirring is not good for biogas). The stirring interval of 6hours is thus recommended for 0.15m3 laboratory batch reactor of cow dung and maize silage.

Optimization of biogas production from a given substrate and digester is an issue that needs to be addressed during the development of anaerobic digestion. To maximize the biogas production rate, the operating parameters that influence anaerobic digestion must be controlled and monitored. This research was carried out using a 0.15 m 3 laboratory digester. The study evaluated the effect of cow dung and maize silage mix ratios (1:1, 1:3, and 3:1) on biogas production which were compared to their pure substrates at a constant temperature of 20°C. The temperatures (20°C, 25°C, and 30°C) were then evaluated using the optimal mix ratio of 3:1 as feedstock. The Temperature of the digester was controlled and monitored using Programmable Temperature Controller (Multispan UTC 421) and the (PLC) running on SIEMENS LOGO. The mix ratios and temperatures showed a significant effect on biogas production (P≤0.05) with mix ratios of 3:1 and 1:1 improving biogas production by 31.24% and 15.52% respectively compared to cow dung. The temperatures of 25°C and 30°C increased biogas by 26.99% and 47.35% and methane increased by 3.92% and 11.76% respectively compared to the mesophilic temperature of 20°C. The study thus, recommends a mix ratio of 3:1 and the optimal temperature of 30°C for a 0.15 m 3 laboratory temperature-controlled fixed-dome anaerobic digester of cow dung and maize silage as a substrate when fed as a batch reactor.

Optimization of biogas production from a given substrate and digester is an issue that needs to be addressed during the development of anaerobic digestion. To maximize the biogas production rate, the operating parameters that influence anaerobic digestion must be controlled and monitored. This research was carried out using a 0.15 m 3 laboratory digester. The study evaluated the effect of cow dung and maize silage mix ratios (1:1, 1:3, and 3:1) on biogas production which were compared to their pure substrates at a constant temperature of 20°C. The temperatures (20°C, 25°C, and 30°C) were then evaluated using the optimal mix ratio of 3:1 as feedstock. The Temperature of the digester was controlled and monitored using Programmable Temperature Controller (Multispan UTC 421) and the (PLC) running on SIEMENS LOGO. The mix ratios and temperatures showed a significant effect on biogas production (P≤0.05) with mix ratios of 3:1 and 1:1 improving biogas production by 31.24% and 15.52% respectively compared to cow dung. The temperatures of 25°C and 30°C increased biogas by 26.99% and 47.35% and methane increased by 3.92% and 11.76% respectively compared to the mesophilic temperature of 20°C. The study thus, recommends a mix ratio of 3:1 and the optimal temperature of 30°C for a 0.15 m 3 laboratory temperature-controlled fixed-dome anaerobic digester of cow dung and maize silage as a substrate when fed as a batch reactor.

This work determined the characteristics of various mix ratios of the cow to pig to sheep manures and ranked them with help of principal component analysis (PCA). Ten mix ratios (by mass) namely 1:1:1, 3:1:1, 1:3:1,1:1:2, 2:1:1, 1:2:1, 1:1:2, 1:3:3, 3:3:1, 3:1:3 of cow, pig and sheep manures respectively were selected. Laboratory analysis was done to determine the total solid (TS) content, carbon to nitrogen ratio, pH, and volatile solid (VS) content using standard procedures. The results obtained (except that of pure feedstocks) were subjected to principal component analysis to determine the principal component scores for the mix ratios to enable ranking. The total solids content of pure cow, pig, and sheep manure were found to be 19.18%, 23.50%, and 30.35% respectively. Corresponding carbon to nitrogen ratios values were 23.68, 13.27 and 29.00, pH values were 6.50, 7.90 and 7.00 and volatile content were 88.37%, 84.57% and 80.00%. Upon mixing the three manures at various mix ratio...

Laboratory testing shows that only 15% of the energy produced by a carefully tended three stone fire is transfered to the cooking pot and 85% is lost to the enviroment. Indoor air pollution resulting from ineficient burning of biomass in traditional cook stove is also major health hazard affecting around 2.7 people globally according to World Health Organisation. This is expected to grow especially with continual use of biomass for cooking hence need for efficient energy conversion technologies. Most stoves based on the principle of gasification have improved thermal eficiencies and low emissions, however, they have adoption problem due to lighting, material used and characterization of key design parameters is inadequate. The main objective of this research was to develop an experimental biomass micro gasifier cook stove that achieves tier 3. The fuel used in the design was saw dust pellets with heat energy calorific value of 4600kca per kg. Version 4.2.3 of the water boiling test ...

Background Neoplasia can be driven by mutations resulting in dysregulation of transcription. In the mesenchymal neoplasm, aggressive fibromatosis, subtractive hybridization identified sterile alpha motif domain 9 (SAMD9) as a substantially down regulated gene in neoplasia. SAMD9 was recently found to be mutated in normophosphatemic familial tumoral calcinosis. In this study, we studied the gene structure and function of SAMD9, and its paralogous gene, SAMD9L, and examined these in a variety of species. Results SAMD9 is located on human chromosome 7q21.2 with a paralogous gene sterile alpha motif domain 9 like (SAMD9L) in the head-to-tail orientation. Although both genes are present in a variety of species, the orthologue for SAMD9 is lost in the mouse lineage due to a unique genomic rearrangement. Both SAMD9 and SAMD9L are ubiquitously expressed in human tissues. SAMD9 is expressed at a lower level in a variety of neoplasms associated with β-catenin stabilization, such as aggressive...