Patrick Kariuki | University of Twente, Faculty of Geoinformation Science and Earth Observation (ITC) (original) (raw)
Papers by Patrick Kariuki
Soil activity is a term generally applied to the ability of a soil to take in and dispose water u... more Soil activity is a term generally applied to the ability of a soil to take in and dispose water under changing moisture conditions. It is due to presence of clay minerals with a net negative charge to neutralise which, water is attracted to the mineral surface. The water molecules are incorporated in the clay structure in between the clay plates and with increased water; both the exchangeable cations and the clay surfaces are hydrated resulting in further separation of the clay plates and swelling of the soils. This has come to be referred to as soil activity. Swelling soils are a major engineering problem and have been estimated to rank first of all the natural hazards in terms of damage to structures, and more so light buildings and pavements making their detection to be one of the most important site investigations in the construction industry. Methods of determining the soil activity have been developed over the years most of which utilise the soil physical properties as indices...
International Journal of Remote Sensing, 2004
Swelling soils are a major geological hazard worldwide and their identification is a major concer... more Swelling soils are a major geological hazard worldwide and their identification is a major concern. Swelling is due to the presence of clay minerals with a potential to accommodate water within their crystal structure. Three common groups, namely smectite, illite and kaolinite, have been identified as indicators of high, moderate and low swelling potential soils where in abundance. This study assessed the potential of spectral data as a tool to recognize the presence of these minerals in soils of varying swelling potential collected from the Antequera area of southern Spain, with the aim of establishing spectral parameters that would in future be applied in remote sensing applications for mapping swelling soils. The coefficient of linear extensibility (COLE) and the linear extensibility (LE rod ), which are established methods for assessing swelling potential and tentative clay mineral allocation, were used as the controlling methods to classify the soils into swelling potential groups and to assign them to dominant clay mineral types. Several spectral parameters were identified as giving a good basis for assigning the soils to domination by either of these clay minerals, and thus to a swelling potential class based on their diagnostic assignment to hydroxyl (OH) and molecular water vibrational processes in clay minerals. The parameters consisted of asymmetries (1400 nm and 2200 nm) that were strong in the presence of the more ordered kaolinite, wavelength position and depth at 1900 nm in abundant smectites, first and second derivative peaks at or near the molecular water feature and the unique presence of absorptions at 2170 nm and 2340 nm in abundant kaolinite and illite. The results show the potential for using reflectance spectroscopy as a tool in the classification of soils into domination by these indicator minerals and thus into swelling potential classes. However, high organic matter and the presence of moisture were found to affect area and depth intensities and would require consideration in such applications.
The use of satellite images during the early stages of mineral exploration has been very successf... more The use of satellite images during the early stages of mineral exploration has been very successful in pointing out the presence of minerals such as smectites and kaolinite important in the identification of hydrothermal alterations. These same minerals are key to the soil swelling properties and their identification from space makes remote sensing a good tool in the characterization of soils in terms of swelling potential. Here several methods used for spectral enhancement of multispectral images are used on an Enhanced Thematic Mapper image (ETM+) in order to detect these minerals on soils, in an area in the central Kenya, where swelling soils are a major problem in the ever-expanding urban centres surrounding the Nairobi city. The techniques were based on separation of the areas based on the presence of iron oxides, hydroxyl bearing minerals and vegetation cover. The imagery was subjected to several data enhancement techniques before interpretations that included; principle compo...
International Journal of Remote Sensing, 2004
Swelling soils are a major geological hazard worldwide and their identification is a major concer... more Swelling soils are a major geological hazard worldwide and their identification is a major concern. Swelling is due to the presence of clay minerals with a potential to accommodate water within their crystal structure. Three common groups, namely smectite, illite and kaolinite, have been identified as indicators of high, moderate and low swelling potential soils where in abundance. This study assessed the potential of spectral data as a tool to recognize the presence of these minerals in soils of varying swelling potential collected from the Antequera area of southern Spain, with the aim of establishing spectral parameters that would in future be applied in remote sensing applications for mapping swelling soils. The coefficient of linear extensibility (COLE) and the linear extensibility (LE rod ), which are established methods for assessing swelling potential and tentative clay mineral allocation, were used as the controlling methods to classify the soils into swelling potential groups and to assign them to dominant clay mineral types. Several spectral parameters were identified as giving a good basis for assigning the soils to domination by either of these clay minerals, and thus to a swelling potential class based on their diagnostic assignment to hydroxyl (OH) and molecular water vibrational processes in clay minerals. The parameters consisted of asymmetries (1400 nm and 2200 nm) that were strong in the presence of the more ordered kaolinite, wavelength position and depth at 1900 nm in abundant smectites, first and second derivative peaks at or near the molecular water feature and the unique presence of absorptions at 2170 nm and 2340 nm in abundant kaolinite and illite. The results show the potential for using reflectance spectroscopy as a tool in the classification of soils into domination by these indicator minerals and thus into swelling potential classes. However, high organic matter and the presence of moisture were found to affect area and depth intensities and would require consideration in such applications.
The use of satellite images during the early stages of mineral exploration has been very successf... more The use of satellite images during the early stages of mineral exploration has been very successful in pointing out the presence of minerals such as smectites and kaolinite important in the identification of hydrothermal alterations. These same minerals are key to the soil swelling properties and their identification from space makes remote sensing a good tool in the characterization of soils in terms of swelling potential. Here several methods used for spectral enhancement of multispectral images are used on an Enhanced Thematic Mapper image (ETM+) in order to detect these minerals on soils, in an area in the central Kenya, where swelling soils are a major problem in the ever-expanding urban centres surrounding the Nairobi city. The techniques were based on separation of the areas based on the presence of iron oxides, hydroxyl bearing minerals and vegetation cover. The imagery was subjected to several data enhancement techniques before interpretations that included; principle component analysis, band rationing and minimum noise fraction. Interpretations were done based on observations made after these manipulations which gave characteristic differences between the heavily vegetated terrain consisting of high iron oxides and thus red soils and the low lying scarcely vegetated grasslands consisting of dark grumosolic soils. Spatially varying micro-topography consisting of gilgai topography and evident in the ETM+ panchromatic band 8 was used to further identify areas with swelling soils. This micro-relief complimented the spectral interpretations. The results were confirmed by field surveys and reveal a new method of integrated image interpretation in terms of spectral and spatial resolutions in identifying soils physical/chemical properties.
International Journal of Remote Sensing, 2003
Swelling soils are a major engineering problem and their detection is one of the most important s... more Swelling soils are a major engineering problem and their detection is one of the most important site investigation undertakings in the construction industry. Methods of their detection have been developed over the years, most of which utilize the soil physical properties as the indices of their identification. Some of these have proved quite expensive and time-consuming. In this research an
International Journal of Remote Sensing, 2003
This study sought to establish diagnostic spectral characteristics in the short-wave infrared (SW... more This study sought to establish diagnostic spectral characteristics in the short-wave infrared (SWIR) that could be used to classify soils in terms of their swelling potential. Three widely accepted soil-swelling indices, i.e. Atterberg limits, cation exchange capacity (CEC) and coefficient of linear extensibility (COLE), were used as controlling parameters to identify these spectral parameters. The results show that several spectral
Community Empowerment and Networking Program is an innovative approach to community development t... more Community Empowerment and Networking Program is an innovative approach to community development that seeks to optimize utilization of local resources and opportunities, without restriction to any specific sectors. The program was developed to effectively produce positive socioeconomic impact within target communities by maximizing synergistic effects from appropriate coordination of three functions of African Institute for Capacity Development (AICAD), namely Research and Development, Training and Extension, Information Network and Documentation. During the process of program development, exhaustive reference was made to experiences from various community development programs around the world.
farming. With population growth and the subsequent scarcity of land available for extensive farmi... more farming. With population growth and the subsequent scarcity of land available for extensive farming, the only option available for these households is to intensify production. For this to be successful, one must understand the divergent patterns of intensification and their relation to the economic needs of households. In a Rift Valley community in Kenya, inter-household heterogeneities in adopting distinctive combinations of particular crop and livestock productions (they are defined as 'croplivestock diversification' or CLD patterns) were observed. Principal component analysis was used to identify the dominant CLD patterns which reflect complementarities between crop and livestock types. This was followed by an assessment of the association between the CLD patterns and the economic returns and manure use of the households. Among the five dominant CLD patterns identified, households that kept improved cattle and grew fruits were found to earn higher incomes and apply more organic manure. Conversely, households that grew staple crops with or without indigenous animals were found to apply less manure. Education, participation in farmers' groups, access to the training centre, and family size were key factors affecting the adoption of CLD patterns.
International Journal of Applied Earth Observation and Geoinformation, 2003
Swelling soils are a major engineering problem and the establishment of new and fast methods for ... more Swelling soils are a major engineering problem and the establishment of new and fast methods for their identification continues to be a major subject of research. Several engineering methods were here used to obtained indices used in the estimation of swelling potential in a group of soil samples with a wide variation in swelling and to classify them into swelling potential classes. The indices were then reduced through factor analysis to obtain a new swell index that was used to obtain the spectral parameters to best correlate with the index where absorption feature mapping, optical density, and derivative spectral data analysis methods were used to establish these parameters. The spectral parameters found to have high correlations with the swell index were then used to establish statistical empirical models to quantify soil swelling from spectral data. The physical understanding of these spectral parameters was also sought and the results show a close relationship between the clay mineralogy related bound water and hydroxyl spectral features in the soil spectra and the swelling index. The bound water parameters gave positive and the hydroxyl related parameters negative correlations to this index. The results confirm the strong influence of the clay mineralogy on the soil properties.
Journal of International Development, 2008
African farmers diversify their livelihood strategies through on-farm and off-farm activities. We... more African farmers diversify their livelihood strategies through on-farm and off-farm activities. We cluster households according to similar livelihood diversification strategies and explore the implications for income levels and sustainable soil management practices. Five main livelihood diversification strategies were being pursued. Households with off-farm income, and those pursuing higher return agricultural activities earned more than twice as much as the lowest income groups, which were the least diversified. They also were more likely to implement soil conservation measures. Policies aimed at improving household well-being need to take into account a wide range of household asset endowments and livelihood strategies being pursued. Copyright © 2007 John Wiley & Sons, Ltd.
Proceedings of The National Academy of Sciences
This article investigates the link between poverty incidence and geographical conditions within r... more This article investigates the link between poverty incidence and geographical conditions within rural locations in Kenya. Evidence from poverty maps for Kenya and other developing countries suggests that poverty and income distribution are not homogenous. We use spatial regression techniques to explore the effects of geographic factors on poverty. Slope, soil type, distance/travel time to public resources, elevation, type of land use, and demographic variables prove to be significant in explaining spatial patterns of poverty. However, differential influence of these and other factors at the location level shows that provinces in Kenya are highly heterogeneous; hence different spatial factors are important in explaining welfare levels in different areas within provinces, suggesting that targeted propoor policies are needed. Policy simulations are conducted to explore the impact of various interventions on locationlevel poverty levels. Investments in roads and improvements in soil fertility are shown to potentially reduce poverty rates, with differential impacts in different regions.
Engineering Geology, 2004
Soil swelling is a term generally applied to the ability of a soil to undergo large changes in vo... more Soil swelling is a term generally applied to the ability of a soil to undergo large changes in volume due to increased moisture content. Several commonly used swelling potential indices, namely Atterberg limits, coefficient of linear extensibility (COLE), cation exchange capacity (CEC) tests and saturated moisture content test (SP) were used to estimate the swelling potential of a group of soil samples representing the whole range of swelling potential. Correlations between the various indices and the potential volume change were obtained and used to determine the potential of each to be included in the establishment of an expansive soil index (ESI), a summation of the indices. The outcome is a set of reliable soil-swelling indices for different levels of risk.
Soil activity is a term generally applied to the ability of a soil to take in and dispose water u... more Soil activity is a term generally applied to the ability of a soil to take in and dispose water under changing moisture conditions. It is due to presence of clay minerals with a net negative charge to neutralise which, water is attracted to the mineral surface. The water molecules are incorporated in the clay structure in between the clay plates and with increased water; both the exchangeable cations and the clay surfaces are hydrated resulting in further separation of the clay plates and swelling of the soils. This has come to be referred to as soil activity. Swelling soils are a major engineering problem and have been estimated to rank first of all the natural hazards in terms of damage to structures, and more so light buildings and pavements making their detection to be one of the most important site investigations in the construction industry. Methods of determining the soil activity have been developed over the years most of which utilise the soil physical properties as indices...
International Journal of Remote Sensing, 2004
Swelling soils are a major geological hazard worldwide and their identification is a major concer... more Swelling soils are a major geological hazard worldwide and their identification is a major concern. Swelling is due to the presence of clay minerals with a potential to accommodate water within their crystal structure. Three common groups, namely smectite, illite and kaolinite, have been identified as indicators of high, moderate and low swelling potential soils where in abundance. This study assessed the potential of spectral data as a tool to recognize the presence of these minerals in soils of varying swelling potential collected from the Antequera area of southern Spain, with the aim of establishing spectral parameters that would in future be applied in remote sensing applications for mapping swelling soils. The coefficient of linear extensibility (COLE) and the linear extensibility (LE rod ), which are established methods for assessing swelling potential and tentative clay mineral allocation, were used as the controlling methods to classify the soils into swelling potential groups and to assign them to dominant clay mineral types. Several spectral parameters were identified as giving a good basis for assigning the soils to domination by either of these clay minerals, and thus to a swelling potential class based on their diagnostic assignment to hydroxyl (OH) and molecular water vibrational processes in clay minerals. The parameters consisted of asymmetries (1400 nm and 2200 nm) that were strong in the presence of the more ordered kaolinite, wavelength position and depth at 1900 nm in abundant smectites, first and second derivative peaks at or near the molecular water feature and the unique presence of absorptions at 2170 nm and 2340 nm in abundant kaolinite and illite. The results show the potential for using reflectance spectroscopy as a tool in the classification of soils into domination by these indicator minerals and thus into swelling potential classes. However, high organic matter and the presence of moisture were found to affect area and depth intensities and would require consideration in such applications.
The use of satellite images during the early stages of mineral exploration has been very successf... more The use of satellite images during the early stages of mineral exploration has been very successful in pointing out the presence of minerals such as smectites and kaolinite important in the identification of hydrothermal alterations. These same minerals are key to the soil swelling properties and their identification from space makes remote sensing a good tool in the characterization of soils in terms of swelling potential. Here several methods used for spectral enhancement of multispectral images are used on an Enhanced Thematic Mapper image (ETM+) in order to detect these minerals on soils, in an area in the central Kenya, where swelling soils are a major problem in the ever-expanding urban centres surrounding the Nairobi city. The techniques were based on separation of the areas based on the presence of iron oxides, hydroxyl bearing minerals and vegetation cover. The imagery was subjected to several data enhancement techniques before interpretations that included; principle compo...
International Journal of Remote Sensing, 2004
Swelling soils are a major geological hazard worldwide and their identification is a major concer... more Swelling soils are a major geological hazard worldwide and their identification is a major concern. Swelling is due to the presence of clay minerals with a potential to accommodate water within their crystal structure. Three common groups, namely smectite, illite and kaolinite, have been identified as indicators of high, moderate and low swelling potential soils where in abundance. This study assessed the potential of spectral data as a tool to recognize the presence of these minerals in soils of varying swelling potential collected from the Antequera area of southern Spain, with the aim of establishing spectral parameters that would in future be applied in remote sensing applications for mapping swelling soils. The coefficient of linear extensibility (COLE) and the linear extensibility (LE rod ), which are established methods for assessing swelling potential and tentative clay mineral allocation, were used as the controlling methods to classify the soils into swelling potential groups and to assign them to dominant clay mineral types. Several spectral parameters were identified as giving a good basis for assigning the soils to domination by either of these clay minerals, and thus to a swelling potential class based on their diagnostic assignment to hydroxyl (OH) and molecular water vibrational processes in clay minerals. The parameters consisted of asymmetries (1400 nm and 2200 nm) that were strong in the presence of the more ordered kaolinite, wavelength position and depth at 1900 nm in abundant smectites, first and second derivative peaks at or near the molecular water feature and the unique presence of absorptions at 2170 nm and 2340 nm in abundant kaolinite and illite. The results show the potential for using reflectance spectroscopy as a tool in the classification of soils into domination by these indicator minerals and thus into swelling potential classes. However, high organic matter and the presence of moisture were found to affect area and depth intensities and would require consideration in such applications.
The use of satellite images during the early stages of mineral exploration has been very successf... more The use of satellite images during the early stages of mineral exploration has been very successful in pointing out the presence of minerals such as smectites and kaolinite important in the identification of hydrothermal alterations. These same minerals are key to the soil swelling properties and their identification from space makes remote sensing a good tool in the characterization of soils in terms of swelling potential. Here several methods used for spectral enhancement of multispectral images are used on an Enhanced Thematic Mapper image (ETM+) in order to detect these minerals on soils, in an area in the central Kenya, where swelling soils are a major problem in the ever-expanding urban centres surrounding the Nairobi city. The techniques were based on separation of the areas based on the presence of iron oxides, hydroxyl bearing minerals and vegetation cover. The imagery was subjected to several data enhancement techniques before interpretations that included; principle component analysis, band rationing and minimum noise fraction. Interpretations were done based on observations made after these manipulations which gave characteristic differences between the heavily vegetated terrain consisting of high iron oxides and thus red soils and the low lying scarcely vegetated grasslands consisting of dark grumosolic soils. Spatially varying micro-topography consisting of gilgai topography and evident in the ETM+ panchromatic band 8 was used to further identify areas with swelling soils. This micro-relief complimented the spectral interpretations. The results were confirmed by field surveys and reveal a new method of integrated image interpretation in terms of spectral and spatial resolutions in identifying soils physical/chemical properties.
International Journal of Remote Sensing, 2003
Swelling soils are a major engineering problem and their detection is one of the most important s... more Swelling soils are a major engineering problem and their detection is one of the most important site investigation undertakings in the construction industry. Methods of their detection have been developed over the years, most of which utilize the soil physical properties as the indices of their identification. Some of these have proved quite expensive and time-consuming. In this research an
International Journal of Remote Sensing, 2003
This study sought to establish diagnostic spectral characteristics in the short-wave infrared (SW... more This study sought to establish diagnostic spectral characteristics in the short-wave infrared (SWIR) that could be used to classify soils in terms of their swelling potential. Three widely accepted soil-swelling indices, i.e. Atterberg limits, cation exchange capacity (CEC) and coefficient of linear extensibility (COLE), were used as controlling parameters to identify these spectral parameters. The results show that several spectral
Community Empowerment and Networking Program is an innovative approach to community development t... more Community Empowerment and Networking Program is an innovative approach to community development that seeks to optimize utilization of local resources and opportunities, without restriction to any specific sectors. The program was developed to effectively produce positive socioeconomic impact within target communities by maximizing synergistic effects from appropriate coordination of three functions of African Institute for Capacity Development (AICAD), namely Research and Development, Training and Extension, Information Network and Documentation. During the process of program development, exhaustive reference was made to experiences from various community development programs around the world.
farming. With population growth and the subsequent scarcity of land available for extensive farmi... more farming. With population growth and the subsequent scarcity of land available for extensive farming, the only option available for these households is to intensify production. For this to be successful, one must understand the divergent patterns of intensification and their relation to the economic needs of households. In a Rift Valley community in Kenya, inter-household heterogeneities in adopting distinctive combinations of particular crop and livestock productions (they are defined as 'croplivestock diversification' or CLD patterns) were observed. Principal component analysis was used to identify the dominant CLD patterns which reflect complementarities between crop and livestock types. This was followed by an assessment of the association between the CLD patterns and the economic returns and manure use of the households. Among the five dominant CLD patterns identified, households that kept improved cattle and grew fruits were found to earn higher incomes and apply more organic manure. Conversely, households that grew staple crops with or without indigenous animals were found to apply less manure. Education, participation in farmers' groups, access to the training centre, and family size were key factors affecting the adoption of CLD patterns.
International Journal of Applied Earth Observation and Geoinformation, 2003
Swelling soils are a major engineering problem and the establishment of new and fast methods for ... more Swelling soils are a major engineering problem and the establishment of new and fast methods for their identification continues to be a major subject of research. Several engineering methods were here used to obtained indices used in the estimation of swelling potential in a group of soil samples with a wide variation in swelling and to classify them into swelling potential classes. The indices were then reduced through factor analysis to obtain a new swell index that was used to obtain the spectral parameters to best correlate with the index where absorption feature mapping, optical density, and derivative spectral data analysis methods were used to establish these parameters. The spectral parameters found to have high correlations with the swell index were then used to establish statistical empirical models to quantify soil swelling from spectral data. The physical understanding of these spectral parameters was also sought and the results show a close relationship between the clay mineralogy related bound water and hydroxyl spectral features in the soil spectra and the swelling index. The bound water parameters gave positive and the hydroxyl related parameters negative correlations to this index. The results confirm the strong influence of the clay mineralogy on the soil properties.
Journal of International Development, 2008
African farmers diversify their livelihood strategies through on-farm and off-farm activities. We... more African farmers diversify their livelihood strategies through on-farm and off-farm activities. We cluster households according to similar livelihood diversification strategies and explore the implications for income levels and sustainable soil management practices. Five main livelihood diversification strategies were being pursued. Households with off-farm income, and those pursuing higher return agricultural activities earned more than twice as much as the lowest income groups, which were the least diversified. They also were more likely to implement soil conservation measures. Policies aimed at improving household well-being need to take into account a wide range of household asset endowments and livelihood strategies being pursued. Copyright © 2007 John Wiley & Sons, Ltd.
Proceedings of The National Academy of Sciences
This article investigates the link between poverty incidence and geographical conditions within r... more This article investigates the link between poverty incidence and geographical conditions within rural locations in Kenya. Evidence from poverty maps for Kenya and other developing countries suggests that poverty and income distribution are not homogenous. We use spatial regression techniques to explore the effects of geographic factors on poverty. Slope, soil type, distance/travel time to public resources, elevation, type of land use, and demographic variables prove to be significant in explaining spatial patterns of poverty. However, differential influence of these and other factors at the location level shows that provinces in Kenya are highly heterogeneous; hence different spatial factors are important in explaining welfare levels in different areas within provinces, suggesting that targeted propoor policies are needed. Policy simulations are conducted to explore the impact of various interventions on locationlevel poverty levels. Investments in roads and improvements in soil fertility are shown to potentially reduce poverty rates, with differential impacts in different regions.
Engineering Geology, 2004
Soil swelling is a term generally applied to the ability of a soil to undergo large changes in vo... more Soil swelling is a term generally applied to the ability of a soil to undergo large changes in volume due to increased moisture content. Several commonly used swelling potential indices, namely Atterberg limits, coefficient of linear extensibility (COLE), cation exchange capacity (CEC) tests and saturated moisture content test (SP) were used to estimate the swelling potential of a group of soil samples representing the whole range of swelling potential. Correlations between the various indices and the potential volume change were obtained and used to determine the potential of each to be included in the establishment of an expansive soil index (ESI), a summation of the indices. The outcome is a set of reliable soil-swelling indices for different levels of risk.