Publications


2017

Ngecu, WM, Thenya T, Ngatia J.  2017.  Title : High community expectation against low societal transformation through community based income generating activities. Analysis of Participatory forest management in Kenya 2005-2013 . International Journal of Scientific Research and Management. 5(6) AbstractFull Text

The implementation of the participatory forest management (PFM) starting 2005 was meant to help in forest management and also assist the forest adjacent communities to benefit from these forest based resources through agreement with Kenya forest Service (KFS). Analysis of socio-economic reports and associated participatory forest management plan (PFMPs) undertaken between 2005 and 2013, indicate sizeable income generating projects (IGP) as part of social function of forest such as recreation have not been realised by community forest association (CFA). It is notable that several facilitating factors such as proximity to major urban areas and significant tourism circuits, necessary for development of these sites have had no impact. In some sites development of business plan did not manage to take IGP to the desired level. This failure leaves the CFA in the same status prior to the implementation of PFM in spite of huge resources invested in mapping and detailing resources potential. The CFA stakeholder’s composition, a structural weakness that failures to include more able and literate local stakeholders (business and professionals) is a major obstacle to enabling exploitation of forest ecosystems potential, thereby remaining localised and a closed unit. Thus, there is need for paradigm shift in terms CFA empowerment for exploitation of social functions of forest resources

2014

Ngecu, WM, MATHU ELIUDM, Onyancha CK, Mwea SK.  2014.  Geophysical resistivity survey in subsurface characterization for heavy construction in Nairobi city, Kenya. International Journal of Geophysics.. (605176) Abstract

Nairobi City is located in an area that may have been part of a large lake or a series of lakes
that extended from Ol Doinyo Sabuk to almost Kajiado in the Tertiary Period. Volcanic rocks
deposited in these lakes vary in lateral and vertical extent and in strength. Geotechnical
investigation of sites with high variability by use of boreholes can be very costly. Electrical
resistivity surveys are cheaper and quicker. The investigation program in this study involve d
1-D geophysical resistivity surveys carried out at 48 sites with electrode distances ranging
between 80 m and 500 m. The focus of the study was on how site investigations can be
carried out cheaply and quickly in the context of design of heavy buildings and in
underground excavations in Nairobi City.

Ngecu, W, MATHU ELIUDM, Onyancha C, Mwea S.  2014.  Effects of drilling deep tube wells in the urban areas of Nairobi city, Kenya. ARPN Journal of Earth Sciences. 3(1) AbstractFull Text

The number of boreholes for abstracting water from aquifers beneath Nairobi City increased from 2 in the year 1927 to about 2500 in the year According to the Republic of Kenya Population and Housing Census, the urban population of Nairobi City increased from 29,864 in 1928 to 3,138,295 in Substantial groundwater drawdown has been noted in individual boreholes that supply the growing population in some localities. The purpose of this study was to investigate the variation in water rest levels across Nairobi City during the 80 year period and estimate the surface settlement that can result from groundwater exploitation. The groundwater static level variations in space and time were analysed on Surfer 9 software and the average rest levels in boreholes between 1927 and 2009 were calculated. Using the hydrogeological data obtained from drilling, an estimate of ground settlement that could result from continuous drawdown was made from formulae obtained from past studies done elsewhere. The results indicate that that the groundwater rest levels have dropped with an average of 79 m in the last 80 years and a probable settlement of m to 5.9 m could result from groundwater depletion from aquifers and clay aquitards over a long period of time. Between the ground surface and the clay aquitards are the dense Nairobi Phonolite and/or Nairobi Trachyte. The probable settlement of 5.9 m should serve as a wakeup call to put up measures that can mitigate subsidence and the related consequences in Nairobi City. Indeed, 67% of the drop in rest levels has occurred in the last two decades during which more than 1000 additional wells have been drilled. Keywords: tube wells, groundwater, abstraction, static level, settlement

2011

Ngecu, W, Khudheyer AF, Mahmoud MS.  2011.  Numerical analysis of fin-tube plate heat exchanger by using CFD technique. Journal of Engineering and Applied Sciences. 6(7):1-12. AbstractFull Text

Three-dimensional CFD simulations are carried out to investigate heat transfer and fluid flow
characteristics of a two-row plain fin-and-tube heat exchanger using Open FOAM, an open-
source CFD code. Heat transfer and pressure drop characteristics of the heat exchanger are
investigated for Reynolds numbers ranging from 330 to 7000. Model geometry is created,
meshed, calculated, and post-processed using open source software. Fluid flow and heat
transfer are simulated and results compared using both laminar and turbulent flow models (k-
epsilon, and Menter SST k-omega), with steady-state solvers to calculate pressure drop,
flow, and temperature fields. Model validation is carried out by comparing the simulated
case friction factor f and Colburn factor j to experimental results from the literature.

Ngecu, W, MATHU ELIUDM, Onyancha C, Mwea S.  2011.  A study on the engineering behaviour of Nairobi subsoil. Academic Journals. AbstractFull Text

Nairobi City is underlain by volcanic materials that resulted from the formation of the rift valley. Some of the challenges that face design of structures in the city include: the need to develop structures in areas with poor site conditions; distress in structures that could be related to foundation conditions; encounter of unexpected subsoil conditions even after carrying out some geotechnical investigations, and; development of defects related to adjacent deep excavation. The objectives of this study were: to investigate the qualitative and quantitative properties of subsurface materials, to establish the engineering property variations and to provide properties that represent the best estimates. Information available for this study included; Atterberg limits, grading, consolidation, swell and collapse, triaxial shear and direct shear, point load and unconfined compressive strength. Failure investigation and resistivity survey were carried out to fill the gaps in the available information. The results indicate that the engineering properties of the materials are very variable. Material property variations and the expected performance of the various subsoil materials are provided. The study concluded that before construction, it is necessary to carry out geotechnical investigations to delineate sensitive soils, determine weak and strong spots and evaluate the relationship between total and differential settlements.

Onyancha, CK, Mathu EM, Mwea SK, Ngecu WM.  2011.  DEALING WITH SENSITIVE AND VARIABLE SOILS IN NAIROBI CITY. Website

2004

Ngecu, W, Nyamai C, Erima G.  2004.  The extent and Significance of mass-movements in Eastern Africa: Case studies of some major landslides in Uganda and Kenya. AbstractWebsite

The East African region has experienced major landslides in recent years. These landslides have caused many fatalities and injuries, loss of many hectares of productive farmlands and destruction to infrastructure such as roads, railways and bridges. The warm and wet climate of the landslide-prone regions causes rapid weathering and produces a regolith weaker than the underlying rock with an interface between the two layers. This interface serves as the most common plane along which landslides are initiated once it becomes saturated. Landslides in the region are associated with steep topography, human activities such as deforestation, overgrazing, and unplanned farming on steep slopes and are induced by earthquakes and high intensity of rainfall. The landslide-prone areas are agriculturally very productive and the inhabitants depend on agriculture for their livelihood. The areas also contribute substantially to the national food reserve. The landslides are therefore a burden to the economies of the individual farmers and national governments of the region.

2003

MATHU, PROFMUTHUMBIELIUD, MATHU PROFMUTHUMBIELIUD, M PROFNGECUWILSON.  2003.  Environmental degradation through quarrying: A case study of Kangudo. Kenya Literature Bureau.. : Asian Journal of Plant Sciences Abstract
Tala Quarrry in African Geoscience Review Vol. 9 Number 4 pp. 385-396.  

2000

M, PROFNGECUWILSON.  2000.  Ground subsidence and its socioeconomic implications on the population. A case study of Nakuru area in Central Rift Valley, Kenya.. Environmental Geology 39(6), 567-576.. : Asian Journal of Plant Sciences Abstract
Tala Quarrry in African Geoscience Review Vol. 9 Number 4 pp. 385-396.  

1999

M, PROFNGECUWILSON.  1999.  The environmental impacts of landslides on the population living on the eastern footslopes of Aberdare Ranges in Kenya: A case study of Maringa Village Landslide.. Journal of Environmental Geology (38) 3, pp 259-264.. : Asian Journal of Plant Sciences Abstract
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MATHU, PROFMUTHUMBIELIUD, MATHU PROFMUTHUMBIELIUD, M PROFNGECUWILSON.  1999.  The El Nino triggered landslides and their socio-economic impacts in Kenya, Episodes 22:284-288.. Journal of Environmental Geology (38) 3, pp 259-264.. : Asian Journal of Plant Sciences Abstract
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M, PROFNGECUWILSON.  1999.  Lithostratigraphic and facies distribution of Pleistocene sediments in southern Kenya Rift Valley at Munyu wa Gicheru Formation. Journal of African Earth Sciences, Volume 29/2. Pp. 411-421.. : Asian Journal of Plant Sciences Abstract
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M, PROFNGECUWILSON.  1999.  The Archaean Sulphide rich turbidites of the Kavirondian Group, Nyanzian Shield, Western Kenya.. Journal of African Earth Sciences, Volume 28/42 pp 56-57. : Asian Journal of Plant Sciences Abstract
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1994

1993

1991

Mathu, EM, Ngecu WM, Nyamai CM, Davies TC.  1991.  Proterozoic island tectonism in the Kenyan Mozambique belt east of Nairobi.

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