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2005

Biamah, E. K; Stroosnijder, OL; CT.  2005.  Watershed conservation in semi-arid Kenya. Abstract

Over the past three decades, agricultural watersheds in semi-arid Kenya have experienced some rapid decline in soil and crop productivity due to severe soil erosion, low soil water, low soil fertility and high soil crusting and compaction. Thus, the management of these watersheds requires some good understanding of agricultural drought, stratification of production zones according to slope, and suitable conservation options that include in-situ water conservation and runoff utilization. The planning of watershed conservation requires the application of runoff models in the selection of interventions that reduce upstream flood magnitude and downstream sedimentation. Successful interventions can be introduced under enabling conditions to farmers at various hierarchical policy levels. A few of these enabling conditions that are elaborated upon include agricultural policy, focus on smallholder agriculture and public¬community partnerships.

KIPNGETICH, PROFBIAMAHELIJAH.  2005.  Biamah, E.K., G. Sterk, T.C. Sharma. 2005. Analysis of agricultural drought in Iiuni, Eastern Kenya: Application of a Markov model. J. Hydrol. Processes (2005).. Wageningen University and Research Centre Publication. ISBN 90-6754-861-8. Also published as thesis (2005) by Wageningen University, ISBN 90-8504-178-3.. : Kisipan, M.L. Abstract
In semi arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop performance and yield. The objective of this study was to stochastically simulate the behaviour of dry and wet spells and rainsums in Iiuni watershed, Kenya. The stochastic behaviour of the longest dry and wet spells (runs) and largest rainsums were simulated using a Markov (order 1) model. There were eight raingauge stations within the watershed. The entire analysis was carried out using probability parameters, i.e. mean, variance, simple and conditional probabilities of dry and rain days. An analysis of variance test (ANOVA) was used to establish significant differences in rainfall characteristics between the eight stations. An analysis of the number of rain days and rainfall amount per rain day was done on a monthly basis to establish the distribution and reliability of seasonal rainfall. The graphical comparison of simulated cumulative distribution functions (cdfs) of the longest spells and largest rainsums showed Markovian dependence or persistence. The longest dry spells could extend to 24 days in the long rainy season and 12 in the short rainy season. At 50% (median) probability level, the largest rainsums were 91 mm for the long rainy season and 136 mm for the short rainy season. The short rains were more reliable for crop production than the long rains. The Markov model performed well and gave adequate simulations of the spells and rainsums under semi arid conditions.
KIPNGETICH, PROFBIAMAHELIJAH.  2005.  Omuto, T.C., Shepherd, K.D., Walsh, M.G., Coe, R., Biamah, E.K., 2005. Spectral reflectance screening of soil physical degradation using CART. Paper submitted to Journal of Remote Sensing of Environment.. Wageningen University and Research Centre Publication. ISBN 90-6754-861-8. Also published as thesis (2005) by Wageningen University, ISBN 90-8504-178-3.. : Kisipan, M.L. Abstract
In semi arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop productivity. Model simulation of the stochastic behaviour of dry and wet spells and rainsums provides some insights into: the differences in rainfall characteristics within an agricultural watershed; and distribution and reliability of seasonal rainfall for various uses. The longest dry spell analysis is of practical relevance to the selection of the best conservation practices (including conservation tillage) for soil and water management whilst the largest rainsum analysis can be used to determine the watershed runoff volume and discharges that would assist in the design of flood and erosion control structures, and the design of runoff water catchment systems (RWCS), which are essential for supplementary irrigation in semi arid Kenya. This study adopted an agro-hydrologic systems approach to the mitigation of agricultural drought at micro, meso and macro scale levels within an agricultural watershed. This approach had its premise that many agricultural drought problems in unstable ecosystems are best solved through farmers interventions at the micro scale level, conservation planning at the meso scale level and resource management at the macro scale level. Thus, the adopted agro-hydrologic systems approach is holistic and aimed at optimizing soil and water management in hydrologically defined geographical areas. The three levels of agricultural drought mitigation should be hierarchical and must consider all factors influencing the hydrologic and hydraulic properties of dominant soils in semi arid Kenya.
KIPNGETICH, PROFBIAMAHELIJAH.  2005.  Omuto, T.C., Shepherd, K.D., Walsh, M.G., Coe, R., Biamah, E.K., 2005. Bio-exponential modeling of watershed water retention Characteristics. Paper submitted to European Journal of Soil Science.. Wageningen University and Research Centre Publication. ISBN 90-6754-861-8. Also published as thesis (2005) by Wageningen University, ISBN 90-8504-178-3.. : Kisipan, M.L. Abstract
In semi arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop productivity. Model simulation of the stochastic behaviour of dry and wet spells and rainsums provides some insights into: the differences in rainfall characteristics within an agricultural watershed; and distribution and reliability of seasonal rainfall for various uses. The longest dry spell analysis is of practical relevance to the selection of the best conservation practices (including conservation tillage) for soil and water management whilst the largest rainsum analysis can be used to determine the watershed runoff volume and discharges that would assist in the design of flood and erosion control structures, and the design of runoff water catchment systems (RWCS), which are essential for supplementary irrigation in semi arid Kenya. This study adopted an agro-hydrologic systems approach to the mitigation of agricultural drought at micro, meso and macro scale levels within an agricultural watershed. This approach had its premise that many agricultural drought problems in unstable ecosystems are best solved through farmers interventions at the micro scale level, conservation planning at the meso scale level and resource management at the macro scale level. Thus, the adopted agro-hydrologic systems approach is holistic and aimed at optimizing soil and water management in hydrologically defined geographical areas. The three levels of agricultural drought mitigation should be hierarchical and must consider all factors influencing the hydrologic and hydraulic properties of dominant soils in semi arid Kenya.
KIPNGETICH, PROFBIAMAHELIJAH.  2005.  Biamah, E.K., Gichuki. F., 2004. Land and Water Management for Poverty Alleviation: Experiences from Iiuni Watershed, Machakos District, Kenya. Paper submitted to Journal of WaterSA, South Africa.. Wageningen University and Research Centre Publication. ISBN 90-6754-861-8. Also published as thesis (2005) by Wageningen University, ISBN 90-8504-178-3.. : Kisipan, M.L. Abstract
In semi arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop productivity. Model simulation of the stochastic behaviour of dry and wet spells and rainsums provides some insights into: the differences in rainfall characteristics within an agricultural watershed; and distribution and reliability of seasonal rainfall for various uses. The longest dry spell analysis is of practical relevance to the selection of the best conservation practices (including conservation tillage) for soil and water management whilst the largest rainsum analysis can be used to determine the watershed runoff volume and discharges that would assist in the design of flood and erosion control structures, and the design of runoff water catchment systems (RWCS), which are essential for supplementary irrigation in semi arid Kenya. This study adopted an agro-hydrologic systems approach to the mitigation of agricultural drought at micro, meso and macro scale levels within an agricultural watershed. This approach had its premise that many agricultural drought problems in unstable ecosystems are best solved through farmers interventions at the micro scale level, conservation planning at the meso scale level and resource management at the macro scale level. Thus, the adopted agro-hydrologic systems approach is holistic and aimed at optimizing soil and water management in hydrologically defined geographical areas. The three levels of agricultural drought mitigation should be hierarchical and must consider all factors influencing the hydrologic and hydraulic properties of dominant soils in semi arid Kenya.
KIPNGETICH, PROFBIAMAHELIJAH.  2005.  Biamah, E.K., Stroosnijder, L., Omuto, C.T., 2005. Watershed Conservation in Semi-arid Kenya. Paper accepted for publication by Physics and Chemistry of the Earth Journal (but yet to receive official communication), an Elsevier Science Publication.. Wageningen University and Research Centre Publication. ISBN 90-6754-861-8. Also published as thesis (2005) by Wageningen University, ISBN 90-8504-178-3.. : Kisipan, M.L. Abstract
In semi arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop productivity. Model simulation of the stochastic behaviour of dry and wet spells and rainsums provides some insights into: the differences in rainfall characteristics within an agricultural watershed; and distribution and reliability of seasonal rainfall for various uses. The longest dry spell analysis is of practical relevance to the selection of the best conservation practices (including conservation tillage) for soil and water management whilst the largest rainsum analysis can be used to determine the watershed runoff volume and discharges that would assist in the design of flood and erosion control structures, and the design of runoff water catchment systems (RWCS), which are essential for supplementary irrigation in semi arid Kenya. This study adopted an agro-hydrologic systems approach to the mitigation of agricultural drought at micro, meso and macro scale levels within an agricultural watershed. This approach had its premise that many agricultural drought problems in unstable ecosystems are best solved through farmers interventions at the micro scale level, conservation planning at the meso scale level and resource management at the macro scale level. Thus, the adopted agro-hydrologic systems approach is holistic and aimed at optimizing soil and water management in hydrologically defined geographical areas. The three levels of agricultural drought mitigation should be hierarchical and must consider all factors influencing the hydrologic and hydraulic properties of dominant soils in semi arid Kenya.
KIPNGETICH, PROFBIAMAHELIJAH.  2005.  Biamah, E.K., Sterk, G., Stroosnijder, L., 2005. Tillage and Farmyard Manure effects on Crusting and Compacting Soils in Semi Arid Kenya. Paper accepted for publication by Euro Asian Journal of Applied Sciences.. Wageningen University and Research Centre Publication. ISBN 90-6754-861-8. Also published as thesis (2005) by Wageningen University, ISBN 90-8504-178-3.. : Kisipan, M.L. Abstract
In semi arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop productivity. Model simulation of the stochastic behaviour of dry and wet spells and rainsums provides some insights into: the differences in rainfall characteristics within an agricultural watershed; and distribution and reliability of seasonal rainfall for various uses. The longest dry spell analysis is of practical relevance to the selection of the best conservation practices (including conservation tillage) for soil and water management whilst the largest rainsum analysis can be used to determine the watershed runoff volume and discharges that would assist in the design of flood and erosion control structures, and the design of runoff water catchment systems (RWCS), which are essential for supplementary irrigation in semi arid Kenya. This study adopted an agro-hydrologic systems approach to the mitigation of agricultural drought at micro, meso and macro scale levels within an agricultural watershed. This approach had its premise that many agricultural drought problems in unstable ecosystems are best solved through farmers interventions at the micro scale level, conservation planning at the meso scale level and resource management at the macro scale level. Thus, the adopted agro-hydrologic systems approach is holistic and aimed at optimizing soil and water management in hydrologically defined geographical areas. The three levels of agricultural drought mitigation should be hierarchical and must consider all factors influencing the hydrologic and hydraulic properties of dominant soils in semi arid Kenya.
KIPNGETICH, PROFBIAMAHELIJAH.  2005.  Gitau, A.N., Gumbe, L.O., Biamah, E.K., 2005. Influence of soil water on stress-Strain Behaviour of a compacting soil in semi arid Kenya. Paper accepted for publication by Soil Tillage and Research Journal, an Elsevier Science Publication (in press).. Wageningen University and Research Centre Publication. ISBN 90-6754-861-8. Also published as thesis (2005) by Wageningen University, ISBN 90-8504-178-3.. : Kisipan, M.L. Abstract
In semi arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop productivity. Model simulation of the stochastic behaviour of dry and wet spells and rainsums provides some insights into: the differences in rainfall characteristics within an agricultural watershed; and distribution and reliability of seasonal rainfall for various uses. The longest dry spell analysis is of practical relevance to the selection of the best conservation practices (including conservation tillage) for soil and water management whilst the largest rainsum analysis can be used to determine the watershed runoff volume and discharges that would assist in the design of flood and erosion control structures, and the design of runoff water catchment systems (RWCS), which are essential for supplementary irrigation in semi arid Kenya. This study adopted an agro-hydrologic systems approach to the mitigation of agricultural drought at micro, meso and macro scale levels within an agricultural watershed. This approach had its premise that many agricultural drought problems in unstable ecosystems are best solved through farmers interventions at the micro scale level, conservation planning at the meso scale level and resource management at the macro scale level. Thus, the adopted agro-hydrologic systems approach is holistic and aimed at optimizing soil and water management in hydrologically defined geographical areas. The three levels of agricultural drought mitigation should be hierarchical and must consider all factors influencing the hydrologic and hydraulic properties of dominant soils in semi arid Kenya.
KIPNGETICH, PROFBIAMAHELIJAH.  2005.  Biamah, E.K., Sterk, G., 2005. Influence of land use changes on watershed runoff volume: Application of AGNPS model in Iiuni watershed, Kenya. Paper accepted for publication by Euro Asian Journal of Applied Sciences.. Wageningen University and Research Centre Publication. ISBN 90-6754-861-8. Also published as thesis (2005) by Wageningen University, ISBN 90-8504-178-3.. : Kisipan, M.L. Abstract
In semi arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop productivity. Model simulation of the stochastic behaviour of dry and wet spells and rainsums provides some insights into: the differences in rainfall characteristics within an agricultural watershed; and distribution and reliability of seasonal rainfall for various uses. The longest dry spell analysis is of practical relevance to the selection of the best conservation practices (including conservation tillage) for soil and water management whilst the largest rainsum analysis can be used to determine the watershed runoff volume and discharges that would assist in the design of flood and erosion control structures, and the design of runoff water catchment systems (RWCS), which are essential for supplementary irrigation in semi arid Kenya. This study adopted an agro-hydrologic systems approach to the mitigation of agricultural drought at micro, meso and macro scale levels within an agricultural watershed. This approach had its premise that many agricultural drought problems in unstable ecosystems are best solved through farmers interventions at the micro scale level, conservation planning at the meso scale level and resource management at the macro scale level. Thus, the adopted agro-hydrologic systems approach is holistic and aimed at optimizing soil and water management in hydrologically defined geographical areas. The three levels of agricultural drought mitigation should be hierarchical and must consider all factors influencing the hydrologic and hydraulic properties of dominant soils in semi arid Kenya.
KIPNGETICH, PROFBIAMAHELIJAH.  2005.  Biamah, E.K., 2005. Coping with Drought: Options for soil and water management in semi-arid Kenya. Tropical Resource Management Papers No. 58 (2005).. Wageningen University and Research Centre Publication. ISBN 90-6754-861-8. Also published as thesis (2005) by Wageningen University, ISBN 90-8504-178-3.. : Kisipan, M.L. Abstract
In semi arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop productivity. Model simulation of the stochastic behaviour of dry and wet spells and rainsums provides some insights into: the differences in rainfall characteristics within an agricultural watershed; and distribution and reliability of seasonal rainfall for various uses. The longest dry spell analysis is of practical relevance to the selection of the best conservation practices (including conservation tillage) for soil and water management whilst the largest rainsum analysis can be used to determine the watershed runoff volume and discharges that would assist in the design of flood and erosion control structures, and the design of runoff water catchment systems (RWCS), which are essential for supplementary irrigation in semi arid Kenya. This study adopted an agro-hydrologic systems approach to the mitigation of agricultural drought at micro, meso and macro scale levels within an agricultural watershed. This approach had its premise that many agricultural drought problems in unstable ecosystems are best solved through farmers interventions at the micro scale level, conservation planning at the meso scale level and resource management at the macro scale level. Thus, the adopted agro-hydrologic systems approach is holistic and aimed at optimizing soil and water management in hydrologically defined geographical areas. The three levels of agricultural drought mitigation should be hierarchical and must consider all factors influencing the hydrologic and hydraulic properties of dominant soils in semi arid Kenya.

2004

KIPNGETICH, PROFBIAMAHELIJAH.  2004.  Biamah, E.K., Sterk, G., Sharma, T.C. 2004. Analysis of agricultural drought in Iiuni, Eastern Kenya: Application of a Markov model. J. Hydrol. Processes.. Wageningen University and Research Centre Publication. ISBN 90-6754-861-8. Also published as thesis (2005) by Wageningen University, ISBN 90-8504-178-3.. : Kisipan, M.L. Abstract
In semi arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop performance and yield. The objective of this study was to stochastically simulate the behaviour of dry and wet spells and rainsums in Iiuni watershed, Kenya. The stochastic behaviour of the longest dry and wet spells (runs) and largest rainsums were simulated using a Markov (order 1) model. There were eight raingauge stations within the watershed. The entire analysis was carried out using probability parameters, i.e. mean, variance, simple and conditional probabilities of dry and rain days. An analysis of variance test (ANOVA) was used to establish significant differences in rainfall characteristics between the eight stations. An analysis of the number of rain days and rainfall amount per rain day was done on a monthly basis to establish the distribution and reliability of seasonal rainfall. The graphical comparison of simulated cumulative distribution functions (cdfs) of the longest spells and largest rainsums showed Markovian dependence or persistence. The longest dry spells could extend to 24 days in the long rainy season and 12 in the short rainy season. At 50% (median) probability level, the largest rainsums were 91 mm for the long rainy season and 136 mm for the short rainy season. The short rains were more reliable for crop production than the long rains. The Markov model performed well and gave adequate simulations of the spells and rainsums under semi arid conditions.
KIPNGETICH, PROFBIAMAHELIJAH.  2004.  Metto, J.K.; Biamah, E.K; R.K. Cherogony; G.A. Mukolwe (2004). Design of on-farm hydraulic structures for regulating road drainage. Submitted to the 15th International Congress of Agricultural Engineering(CIGR) Conference, Beijing, China. October, 2004.. Wageningen University and Research Centre Publication. ISBN 90-6754-861-8. Also published as thesis (2005) by Wageningen University, ISBN 90-8504-178-3.. : Kisipan, M.L. Abstract
In semi arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop performance and yield. The objective of this study was to stochastically simulate the behaviour of dry and wet spells and rainsums in Iiuni watershed, Kenya. The stochastic behaviour of the longest dry and wet spells (runs) and largest rainsums were simulated using a Markov (order 1) model. There were eight raingauge stations within the watershed. The entire analysis was carried out using probability parameters, i.e. mean, variance, simple and conditional probabilities of dry and rain days. An analysis of variance test (ANOVA) was used to establish significant differences in rainfall characteristics between the eight stations. An analysis of the number of rain days and rainfall amount per rain day was done on a monthly basis to establish the distribution and reliability of seasonal rainfall. The graphical comparison of simulated cumulative distribution functions (cdfs) of the longest spells and largest rainsums showed Markovian dependence or persistence. The longest dry spells could extend to 24 days in the long rainy season and 12 in the short rainy season. At 50% (median) probability level, the largest rainsums were 91 mm for the long rainy season and 136 mm for the short rainy season. The short rains were more reliable for crop production than the long rains. The Markov model performed well and gave adequate simulations of the spells and rainsums under semi arid conditions.
KIPNGETICH, PROFBIAMAHELIJAH.  2004.  Biamah, E.K., Stroosnijder, L., 2004. Watershed conservation in semi arid Kenya, Submitted to Physics and chemistry of the earth.. Wageningen University and Research Centre Publication. ISBN 90-6754-861-8. Also published as thesis (2005) by Wageningen University, ISBN 90-8504-178-3.. : Kisipan, M.L. Abstract
In semi arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop performance and yield. The objective of this study was to stochastically simulate the behaviour of dry and wet spells and rainsums in Iiuni watershed, Kenya. The stochastic behaviour of the longest dry and wet spells (runs) and largest rainsums were simulated using a Markov (order 1) model. There were eight raingauge stations within the watershed. The entire analysis was carried out using probability parameters, i.e. mean, variance, simple and conditional probabilities of dry and rain days. An analysis of variance test (ANOVA) was used to establish significant differences in rainfall characteristics between the eight stations. An analysis of the number of rain days and rainfall amount per rain day was done on a monthly basis to establish the distribution and reliability of seasonal rainfall. The graphical comparison of simulated cumulative distribution functions (cdfs) of the longest spells and largest rainsums showed Markovian dependence or persistence. The longest dry spells could extend to 24 days in the long rainy season and 12 in the short rainy season. At 50% (median) probability level, the largest rainsums were 91 mm for the long rainy season and 136 mm for the short rainy season. The short rains were more reliable for crop production than the long rains. The Markov model performed well and gave adequate simulations of the spells and rainsums under semi arid conditions.
KIPNGETICH, PROFBIAMAHELIJAH.  2004.  Omuto, T.C., Walsh, M.G., Shepherd, K.D., Biamah, E.K., 2004. Nonlinear mixed effect fitting of soil hydraulic functions from a large watershed, Minor corrections suggested to paper, corrected and sent back to Journal of Soil Science Society of America.. Wageningen University and Research Centre Publication. ISBN 90-6754-861-8. Also published as thesis (2005) by Wageningen University, ISBN 90-8504-178-3.. : Kisipan, M.L. Abstract
In semi arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop performance and yield. The objective of this study was to stochastically simulate the behaviour of dry and wet spells and rainsums in Iiuni watershed, Kenya. The stochastic behaviour of the longest dry and wet spells (runs) and largest rainsums were simulated using a Markov (order 1) model. There were eight raingauge stations within the watershed. The entire analysis was carried out using probability parameters, i.e. mean, variance, simple and conditional probabilities of dry and rain days. An analysis of variance test (ANOVA) was used to establish significant differences in rainfall characteristics between the eight stations. An analysis of the number of rain days and rainfall amount per rain day was done on a monthly basis to establish the distribution and reliability of seasonal rainfall. The graphical comparison of simulated cumulative distribution functions (cdfs) of the longest spells and largest rainsums showed Markovian dependence or persistence. The longest dry spells could extend to 24 days in the long rainy season and 12 in the short rainy season. At 50% (median) probability level, the largest rainsums were 91 mm for the long rainy season and 136 mm for the short rainy season. The short rains were more reliable for crop production than the long rains. The Markov model performed well and gave adequate simulations of the spells and rainsums under semi arid conditions.

2003

KIPNGETICH, PROFBIAMAHELIJAH.  2003.  Biamah, E.K., Nhlabathi, N., 2003. Conservation tillage practices for dryland crop production in semi arid Kenya: Promotion of conservation tillage techniques for improving household food security in iiuni, Machakos, Kenya. p 45-50. In: Beukes, D., de Vil. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract
In semi arid Kenya, the most dominant soil types are of limited agricultural productivity due to crusting and compaction. The occurrence of soil crusting and compaction is attributed to seasonal rainfall characteristics, physical soil properties and bad tillage practices. Soil crusting and compaction decreases rainwater infiltration and increases surface runoff. Increased and concentrated surface runoff water flow causes severe soil erosion. The objective of this study was to examine the hydrological effects of different tillage practices with and without farmyard manure on infiltration, surface runoff and soil loss of crusting and compacting soils under field and laboratory conditions in semi arid Kenya. Field investigations on infiltration, soil moisture, surface runoff, soil loss, soil bulk density and soil shear strength covered two rainy seasons (short and long rains) and were done on a Chromic Luvisol. The field treatments were zero and conventional tillage, and two farmyard manure applications (5 and 10 Mg/ha). Laboratory investigations on infiltration, time to runoff, surface runoff, soil loss and penetration resistance were conducted under simulated rainfall on four Luvisols for sixty days with the same farmyard manure (5 and 10 Mg/ha) treatments. A regression analysis and a one way ANOVA revealed significant (P<0.05) differences between soil types and treatments. The results obtained showed significant effects of conventional and zero tillage and farmyard manure on infiltration and soil moisture, time to runoff, surface runoff and soil loss. Soil crusting and compaction significantly influenced the hydrological responses of all soil types and treatments. These responses were attributed to seasonal rainfall events of varying amounts, intensities and duration and treatment differences in soil surface conditions and aggregation. Farmyard manure (FYM) application enhanced infiltration and reduced soil crusting and compaction, and surface runoff during the initial stages of the rainy season. But in the mid-stages of the rainy season, the effects of FYM on soil aggregation diminished and resulted in an increase in soil loss. At the end of the rainy season, when soil crusts had formed, some significant decrease in soil loss with FYM treatments was observed. Conventional tillage without farmyard manure led to high surface runoff and soil loss in these structurally unstable soils. Zero tillage performed poorly under these soil conditions because of high soil crusting and compaction, low rainwater infiltration and subsequent increase in surface runoff.
KIPNGETICH, PROFBIAMAHELIJAH.  2003.  Biamah, E.K., Sterk, G., Stroosnijder, L. 2003. Hydrological effects of tillage and farmyard manure on crusting and compacting soils in semi arid Kenya. p 150-158. In: Tullberg, J., Hoogmoed, W. (Eds.), Soil management for sustainability, Proceedings of 1. The University of Queensland, Brisbane, Australia. ISBN 0-646-42496-3.. : Kisipan, M.L. Abstract
In semi arid Kenya, the most dominant soil types are of limited agricultural productivity due to crusting and compaction. The occurrence of soil crusting and compaction is attributed to seasonal rainfall characteristics, physical soil properties and bad tillage practices. Soil crusting and compaction decreases rainwater infiltration and increases surface runoff. Increased and concentrated surface runoff water flow causes severe soil erosion. The objective of this study was to examine the hydrological effects of different tillage practices with and without farmyard manure on infiltration, surface runoff and soil loss of crusting and compacting soils under field and laboratory conditions in semi arid Kenya. Field investigations on infiltration, soil moisture, surface runoff, soil loss, soil bulk density and soil shear strength covered two rainy seasons (short and long rains) and were done on a Chromic Luvisol. The field treatments were zero and conventional tillage, and two farmyard manure applications (5 and 10 Mg/ha). Laboratory investigations on infiltration, time to runoff, surface runoff, soil loss and penetration resistance were conducted under simulated rainfall on four Luvisols for sixty days with the same farmyard manure (5 and 10 Mg/ha) treatments. A regression analysis and a one way ANOVA revealed significant (P<0.05) differences between soil types and treatments. The results obtained showed significant effects of conventional and zero tillage and farmyard manure on infiltration and soil moisture, time to runoff, surface runoff and soil loss. Soil crusting and compaction significantly influenced the hydrological responses of all soil types and treatments. These responses were attributed to seasonal rainfall events of varying amounts, intensities and duration and treatment differences in soil surface conditions and aggregation. Farmyard manure (FYM) application enhanced infiltration and reduced soil crusting and compaction, and surface runoff during the initial stages of the rainy season. But in the mid-stages of the rainy season, the effects of FYM on soil aggregation diminished and resulted in an increase in soil loss. At the end of the rainy season, when soil crusts had formed, some significant decrease in soil loss with FYM treatments was observed. Conventional tillage without farmyard manure led to high surface runoff and soil loss in these structurally unstable soils. Zero tillage performed poorly under these soil conditions because of high soil crusting and compaction, low rainwater infiltration and subsequent increase in surface runoff.
KIPNGETICH, PROFBIAMAHELIJAH.  2003.  Biamah, E.K., Nhlabathi, N., 2003. Conservation tillage practices for dryland crop production in semi arid Kenya: Promotion of conservation tillage techniques for improving household food security in iiuni, Machakos, Kenya. In: Beukes, D., de Villiers, M.. Wageningen University and Research Centre Publication. ISBN 90-6754-861-8. Also published as thesis (2005) by Wageningen University, ISBN 90-8504-178-3.. : Kisipan, M.L. Abstract
In semi arid Kenya, episodes of agricultural droughts of varying severity and duration occur. The occurrence of these agricultural droughts is associated with seasonal rainfall variability and can be reflected by seasonal soil moisture deficits that significantly affect crop performance and yield. The objective of this study was to stochastically simulate the behaviour of dry and wet spells and rainsums in Iiuni watershed, Kenya. The stochastic behaviour of the longest dry and wet spells (runs) and largest rainsums were simulated using a Markov (order 1) model. There were eight raingauge stations within the watershed. The entire analysis was carried out using probability parameters, i.e. mean, variance, simple and conditional probabilities of dry and rain days. An analysis of variance test (ANOVA) was used to establish significant differences in rainfall characteristics between the eight stations. An analysis of the number of rain days and rainfall amount per rain day was done on a monthly basis to establish the distribution and reliability of seasonal rainfall. The graphical comparison of simulated cumulative distribution functions (cdfs) of the longest spells and largest rainsums showed Markovian dependence or persistence. The longest dry spells could extend to 24 days in the long rainy season and 12 in the short rainy season. At 50% (median) probability level, the largest rainsums were 91 mm for the long rainy season and 136 mm for the short rainy season. The short rains were more reliable for crop production than the long rains. The Markov model performed well and gave adequate simulations of the spells and rainsums under semi arid conditions.

2002

KIPNGETICH, PROFBIAMAHELIJAH.  2002.  Biamah, E.K., Sharma, T.C., Stroosnijder, L., 2002. Simulation of watershed peak runoff rate using the Nash Model. JEAE 2 (1) 49-56.. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

KIPNGETICH, PROFBIAMAHELIJAH.  2002.  Biamah, E.K., 2002. Soil and water conservation. In: Managing Dryland Resources: An Extension Manual for Eastern and Southern Africa. International Institute of Rural Reconstruction (IIRR), Nairobi, Kenya. pp 83-99.. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract
In semi arid Kenya, the most dominant soil types are of limited agricultural productivity due to crusting and compaction. The occurrence of soil crusting and compaction is attributed to seasonal rainfall characteristics, physical soil properties and bad tillage practices. Soil crusting and compaction decreases rainwater infiltration and increases surface runoff. Increased and concentrated surface runoff water flow causes severe soil erosion. The objective of this study was to examine the hydrological effects of different tillage practices with and without farmyard manure on infiltration, surface runoff and soil loss of crusting and compacting soils under field and laboratory conditions in semi arid Kenya. Field investigations on infiltration, soil moisture, surface runoff, soil loss, soil bulk density and soil shear strength covered two rainy seasons (short and long rains) and were done on a Chromic Luvisol. The field treatments were zero and conventional tillage, and two farmyard manure applications (5 and 10 Mg/ha). Laboratory investigations on infiltration, time to runoff, surface runoff, soil loss and penetration resistance were conducted under simulated rainfall on four Luvisols for sixty days with the same farmyard manure (5 and 10 Mg/ha) treatments. A regression analysis and a one way ANOVA revealed significant (P<0.05) differences between soil types and treatments. The results obtained showed significant effects of conventional and zero tillage and farmyard manure on infiltration and soil moisture, time to runoff, surface runoff and soil loss. Soil crusting and compaction significantly influenced the hydrological responses of all soil types and treatments. These responses were attributed to seasonal rainfall events of varying amounts, intensities and duration and treatment differences in soil surface conditions and aggregation. Farmyard manure (FYM) application enhanced infiltration and reduced soil crusting and compaction, and surface runoff during the initial stages of the rainy season. But in the mid-stages of the rainy season, the effects of FYM on soil aggregation diminished and resulted in an increase in soil loss. At the end of the rainy season, when soil crusts had formed, some significant decrease in soil loss with FYM treatments was observed. Conventional tillage without farmyard manure led to high surface runoff and soil loss in these structurally unstable soils. Zero tillage performed poorly under these soil conditions because of high soil crusting and compaction, low rainwater infiltration and subsequent increase in surface runoff.

2001

KIPNGETICH, PROFBIAMAHELIJAH.  2001.  Conservation Planning and management of agricultural watersheds; in semi arid Kenya: Strategies and Technological options. Accepted by Engineering in Agriculture and Environmental. Journal of the Kenya Society of Agricultural Engineers, Nairobi, Kenya.. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

KIPNGETICH, PROFBIAMAHELIJAH.  2001.  Design of on-farm hydraulic structures for regulating road drainage. Accepted by Engineering in Agriculture and Environment. Journal of the Kenya Society of Agricultural Engineers, Nairobi, Kenya.. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

KIPNGETICH, PROFBIAMAHELIJAH.  2001.  Simulation of watershed peak runoff discharge using the Nash model Submitted to Discovery and Innovation, Journal of the African Academy of Sciences, Nairobi, Kenya. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

KIPNGETICH, PROFBIAMAHELIJAH.  2001.  Rainfall characteristics and agricultural drought: A stochastic simulation of seasonal dry and wet spells using a Markov model. Submitted to Discovery and Innovation. Journal of the African Academy of Sciences, Nairobi, Kenya.. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

KIPNGETICH, PROFBIAMAHELIJAH.  2001.  Conservation tillage for dryland farming: Promotion of conservation tillage techniques for improving household food security in semi arid Kenya. Paper presented at a Regional Workshop on Conservation Tillage, Arusha. Tanzania.. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

2000

KIPNGETICH, PROFBIAMAHELIJAH.  2000.  Seasonal crop response to conservation tillage under dryland conditions. Proceedings of the 15th International Soil Tillage Research Organization (ISTRO). Dallas Fort Worth, Texas, USA.. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

KIPNGETICH, PROFBIAMAHELIJAH.  2000.  Conservation tillage for dryland farming. Proceedings of a Regional/Wor kshop on Conservation Tillage for Eastern and Southern Africa. Supported by RELMA/Sida. Gitau. A.N. and E.K. Biamah (2000). Influence of selected tillage operations on draft power and. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

1999

KIPNGETICH, PROFBIAMAHELIJAH.  1999.  Suitable Conservation Techniques for the Nyando River Catchment Area. Lake Victoria Basin. Unpublished Study Report. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

1998

KIPNGETICH, PROFBIAMAHELIJAH.  1998.  Biamah, E.K; A.N. Gitau; and R.K. Cherogony(1998a). Temporal hydrologic response of unstable crusting soils in Semi Arid Kenya, Proceedings of the Kenya Society of Agricultural Engineering(KSAE). Nairobi, Kenya. Gicheru, P.T.; C.K.K. Gachene and E.K.Biama. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

KIPNGETICH, PROFBIAMAHELIJAH.  1998.  Biamah, E.K and A.R. Oduor. Soil, Water and Nutrient Management in China: An assessment of environmental degradation, conservation farming strategies and management options for Dryland Agriculture. Unpublished Manuscript.. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

KIPNGETICH, PROFBIAMAHELIJAH.  1998.  Biamah, E.K; L. Stroosnijder and R.K. Cherogony. Effect of tillage on infiltration, runoff and erosion of crusting soils in Semi Arid Kenya. Proceedings of the 13th International Congress of Agricultural Engineering (CIGR). Rabat. Morocco.. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

KIPNGETICH, PROFBIAMAHELIJAH.  1998.  Biamah, E.K; R.K. Cherogony and G.A. Mukolwe. Runoff water harvesting and conservation technologies for dryland crop production and rural water supply in arid and semi arid lands. Proceedings of the 13th International Congress of Agricultural Engineering . Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

KIPNGETICH, PROFBIAMAHELIJAH.  1998.  Biamah, E.K; L. Stroosnijder; T.C. Sharma; and R.K. Cherogony. Temporal and spatial features of Agricultural drought in Semi Arid Kenya: An analysis of seasonal dry and wet spells as requirements for conservation tillage. Proceedings of the 13th Internati. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

KIPNGETICH, PROFBIAMAHELIJAH.  1998.  Biamah. E.K; L. Stroosnijder; T.C. Sharma; and R.K. Cherogony, Effect of conservation tillage on watershed hydrology in Semi Arid Kenya: An application of AGNPS, SCS-CN and Rational Formula runoff models. Proceedings of the 13th International Congress of . Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

1997

KIPNGETICH, PROFBIAMAHELIJAH.  1997.  Biamah, E.K and R.K. Cherogony(1997). Runoff water management technologies for dryland agriculture in arid and Semi arid lards. Proceedings of the International Symposium on Sustainable Farming Systems for Dryland Agricultural in North West China. Yanglin. Bloemfontein, South Africa.. : Kisipan, M.L. Abstract

In semi arid Kenya, the occurrence of flush floods and soil erosion on agricultural watersheds is attributed to intense rainstorm events of short duration. Thus when agricultural watersheds have no erosion control structures in place, the generation of direct runoff would increase with cultivation. Of the two components of runoff namely, runoff volume and peak runoff discharge, the consideration of peak runoff discharge rate is critical to the design of effective hydraulic structures for controlling floods and soil erosion. In order to accurately predict a watershed's peak runoff discharge, it is important to select a model that is deterministic and yet simple to use. The model should be able to consider the time distribution of runoff response as influenced by Watershed characteristics. The time to peak runoff discharge is largely influenced by the time of concentration. The time of concentration depends on the shape, size and relief of the watershed. In Iiuni Watershed, the Nash model, a parsimonious deterministic model, was selected to predict peak runoff discharges. This model uses the instantaneous unit hydrograph principle to simulate the direct runoff hydrographs and estimate peak runoff discharge. The Nash model was applied using input parameters derived from the watershed's rainfall-runoff characteristics. The results obtained showed that the Nash model was good in predicting peak runoff discharges. This statistic of comparison, R2 (coefficient of efficiency) for the model was above 70% for the model which is indicative of good model prediction of peak runoff discharge (Nash and Sutcliffe, 1970). From this analysis, the Nash model is recommended for the estimation of peak runoff discharge from un-gauged agricultural watersheds in Kenya.

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