60 Records out of 22207 Records

Groundwater quality in Samia area of Busia County, Western Kenya

Author: Mang'eni, Fredrick Bwire

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 2012

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Groundwater ; Quality ; Samia Hills ; Busia County ;

Abstract:

This study focuses on the groundwater quality in Samia area, western Kenya. It also investigates the aquifer types and their possible impacts on the water quality. The geology of the area comprises granite-greenstone terrane of Archaean age. The Archaean rocks include the Nyanzian 'supergroup' intruded by igneops complexes and calc-alkaline plutons which comprise the Samia series and acid volcanic units which include the banded iron formation of the Samia hills. The lithological composition of these rocks appear to have profound effects on water quality. The results of this study show that the groundwater is fairly neutral with pH between 6.5 and 7.5. The minor elements like zinc, manganese and iron are within the World Health Organization (WHO) potable water guidelines; similarly fluorides, chlorides, nitrates and sulphate are within safe limits. Chemical analyses of the water indicate geological influence and the hydrochemical facies in the area can be divided into at least two zones; ? Calcium bicarbonate type in the southern and ? Sodium- potassium bicarbonate type in the northern parts of the area. As the groundwater flows from the recharge to the discharge areas, it increases in Total Dissolved Solids (TDS), which is interrupted by geological structures such as fissures, shears or cracks which could be natural, hence altering the water chemistry. Although the waters from most of the drilled boreholes and wells are suitable for most purposes like domestic, agricultural and industrial, the presence of some mineral components (e.g., Ca and Mg) above the required guidelines in some wells make water from these few boreholes unsuitable for laundry and other domestic purposes including cooking. It was noted from this study that for all the drilled wells, the water rest level was above the water struck level providing strong evidence for semi-confined aquifer fields. The water struck level in the area ranges from 28 to 68 m while the water rest level ranges from 10.2 to 30.34 m in depth from the ground surface.

The application of geo-electrical resistivity data to groundwater modelling in hardrock terraine-an integrated approach

Author: K'orowe, Maurice Odondi

Awarding University: Jomo Kenyatta University of Agriculture and Technology, Kenya

Level : PhD

Year: 2009

Holding Libraries: Jomo Kenyatta University of Agriculture and Technology Library ;

Subject Terms: Hydrogeology/Groundwater/Jangaon, Andhra Pradesh, India/ ;

Abstract:

The thesis presents the application of geo-electrical data in the field of hydrogeology. In this regard, two distinct applications of geo-electrical techniques have been carried out One is to determine a theoretical relationship between geo-electrical data and hydraulic parameters by modifying the theories developed in laboratories by Bernabe and Revil (1995) and applying the bond shrinkage process of pore network structures described by Wong et al., (1984). The petrophysical relationship thus established, have been tested with data from a typically hard rock terrain found in the Jangaon sub- watershed, Andhra pradesh, India. Secondly a site-specific relationship between geo-electrical data and an aquifer process namely; natural recharge has been developed and referred to as a natural recharge model for the Jangaon sub-watershed. In order to evaluate the coherence of the geo-electrically derived hydraulic parameters and process, these data have been integrated into a groundwater flow simulation model. To modify the Bernabe and Revil (1995) model, the theories explaining the flow characteristics of a material's pore structure have been modified into a field scale relationship between transmissivity and apparent formation factor of the aquifer materials and a relationship expressed as; In T = In Ba/ig - mk F:. Au m; This theoretical relationship was applied to data from Jangaon sub-watershed. The transmissivity values were obtained from pumping tests done on the boreholes of the area. Formation factors were obtained form geo-electrical data from the borehole sites. The relationship In T=9.9-2.5 InFa which shows that the theoretical relationship explains the relationship between geo-electrical and hydrogeological data. For a site-specific geo-electric recharge model to be developed, two methods were integrated. The first method involves using surface electrical resistivity sounding data to evaluate the resistivity of topsoil layers within the top 3 meters at each site. The second procedure is to determine natural recharge by using the Tritium tagging technique, where the flow of tritiated water within a soil profile is monitored and natural recharge at each injection site is estimated. Consequently, a correlation analysis between the two data sets was carried out with the result that natural recharge correlate very well with 'Composite layer resistivity' to produce a geo-electrical recharge model of the form R=3.1pt-73.71. The geo-electrically derived hydrogeological parameters and processes were used as input parameters into a groundwater flow simulation model. A transient groundwater flow simulation for a time period of one hydrologic cycle was carried out. The simulation period was divided into two stress periods, representing the rainy season and the dry season. At the end of the simulation period, simulated groundwater heads were compared with observed hydraulic heads. The model errors from residual hydraulic heads are less than 10% at all the observation boreholes. Scatter plots of simulated heads versus observed heads at the end of simulation period have a weighted variance of 8.89, indicative of goodness fit.

Application of remote sensing data in exploration of fractured aquifers in central Kajiado area Kenya

Author: Khisa, P P Sifuna

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 2008

Holding Libraries: University of Nairobi Chiromo Library ;

Subject Terms: Hydrology/Water/Groundwater/Remote sensing/Kajiado, Kenya/ ;

Abstract:

A rural groundwater project within the metamorphic and volcanic rock formations in Central Kajiado Area, which is 800km2 in size', was the focus of a research study to develop better borehole siting strategies. The drilling success rate has been low due to low primary porosity and the restriction of groundwater to secondary structural features. Remote sensing data including; Landsat Multispectral Scanner (MSS) imagery and aerial photography were used to interpret linear vegetation, drainage and bedrock features that would indicate underlying groundwater fracture zones. Lineaments were examined in the field and integrated with information from several geo-referenced boreholes. Data analyses focused on the phenomena that contributed to successful boreholes, in order to develop optimal strategies for future borehole siting. Remote sensing data allowed effective mapping of lineaments features that are conducive to groundwater development. Lineaments interpreted on satellite data and aerial photography would form a basis for borehole siting in Central Kajiado Area.

Groundwater model calibration of Ngong area in the Upper Athi Basin using optimal parameter estimation

Author: Wanjara, Robert Magutu

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 2007

Holding Libraries: University of Nairobi Chiromo Library ;

Subject Terms: Water/Groundwater/Models/Upper Athi Basin, Kenya/ ;

Abstract:

Ngong area is a high rainfall zone lying on the eastern ann of the Gregory Rift and underlain by volcanic lava flows that erupted from Ngong and 01 Doinyo volcanoes. It is an important recharge area for the Upper Athi Basin Aquifer. This is because of the high incidence of fractures that strike in a north - south direction. Ngong area forms one of the fastest growing areas with groundwater forming a major component for potable water. To sustainably manage the resource, it is necessary to simulate a flow model in order to make the right decisions. A ground water flow model was calibrated for the area using the inverse method of parameter estimation. Borehole lithological logs, geological reports, topographical maps, hydrogeological and hydrological information were used to develop the conceptual model of the area. The main aquifers consist of the weathered and fractured basalts and trachytes below which lie two layers of the Upper Athi Series aquifer. A semi-confining unit consisting of the Mbagathi trachyte separates the two layers of Upper Athi Series. Fixing those parameters that were mostly insensitive to the observations reduced high parameter correlation in the estimation process. The estimates of these parameters were obtained in the early stages of parameterization. These included all the vertical hydraulic conductivities. Results indicate the lower aquifer to have a higher horizontal hydraulic conductivity (8.8E-06 mlhr) than the two upper aquifers. Vertical leakance from the first layer to the second layer was high at 2.8E-04 mIhr probably due to the high occurrence of fractures in the upper layer but low from the second layer to the third. The high leakance in the first layer is explained by the high incidence of fractures in the layer while the low leakance in the second layer is due to the semi-confining unit of Mbagathi Trachyte. The model indicates a net aquifer recharge of 4.SE-06 mIhr (39.7 mm annually) in this main recharge zone of the upper Athi basin. The flow direction was found to be from the western to easterly direction.

Potential groundwater contamination by nitrate-nitrogen as influenced by irrigation and fertilizer application rates

Author: Taragon, John Kibunei

Awarding University: Jomo Kenyatta University of Agriculture and Technology, Kenya

Level : MSc

Year: 2007

Holding Libraries: Jomo Kenyatta University of Agriculture and Technology Library ;

Subject Terms: Water/Groundwater/Contamination/Nitrogen/Fertilizers/ ;

Abstract:

Agriculture has become one of the major sources of environmental problems in recent past. Population growth over the last three decades, have compelled communities to intensify agricultural production to meet their food demands. Agricultural intensification has entailed the use of large quantities of fertilizer that are aimed at increasing yields per unit piece of land. Nitrogen fertilizers are of major concern from the environmental point of view. High concentrations of nitrogenous compounds cause eutrophication in surface waters. Nitrates in drinking water have been known to cause health problems. Nitrates are soluble in water and thus very mobile throughout the soil horizons and into groundwater. Of concern is the threat to rural people, who obtain their drinking water from shallow wells, dug in intensively cultivated lands.However, fertilization application should be aimed at providing the basic mnumum nutrients for crop production, which will minimize potential of groundwater contamination without lowering the yields. This study was conducted to determine nitrate nitrogen leaching amounts during the crop growth, to evaluate the optimal nitrogen fertilizer application level to minimize the potential of nitrate nitrogen leaching to groundwater and to evaluate the performance of RZWQ Model in predicting nitrate nitrogen leaching during the crop growth Hybrid maize, variety DHOI from Kenya Seed Company, was planted in mid November 2004, in experimental field plots that were setup at JKUAT demonstration Farm. Split plot design was chosen (on a CBRD) to cater for two treatments, irrigation water levels on the main plots and nitrogen fertilizer application rates on the subplots. Irrigation had two levels: Normal Irrigation (NI) and Excess Irrigation (EI). Nitrogen fertilizer was applied at five levels. A control treatment with no fertilizer application was also set up. Treatments were replicated thrice. The amount of nitrate leached over the entire period of maize growing season was measured at intervals of three weeks. For NI at fertilizer rates of 0, 50, 75, 100, 125 and 150 kgNlha, the cumulative nitrate leaching were 4.8, 9.6, 19.1, 23.9, 38.2 and 47.8 kgNlha respectively, whereas for EI and the same levels of fertilizer application, the cumulative nitrate leached were 4.8, 9.6, 28.7, 38.2, 43.0 and 66.9 kgNlha respectively. These results indicated that nitrate leaching increased with fertilizer application rate, for the two levels of irrigation and leaching being highest under EI. Statistical analysis of the two treatments (fertilizer and irrigation) shows that decreasing fertilization rates is substantially more effective in reducing nitrate leaching. Irrigation does not significantly affect the bulk of nitrate leaching although it tends to enhance/influence leaching process, especially at the higher rate of fertilizer application. Under soil and climatic conditions of the study area, optimal grain yields of 7222 kg/ha and lower nitrate leaching amounts (23.9 kgNlha) may be obtained at fertilizer application rate of 100 kgNlha. For the same levels of fertilizer application, the RZWQM predicted nitrate leaching amounts of 0.2, 13.3,25.1,38.1,52.1 and 66.8 kgNlha under EI whereas for NI, the model predicted values of 0.2, 12.8,23.3, 34.4, 45.6 and 57.2 kgNlha. These represent an average percent difference (%D) between observed and predicted values of +2.9% and +20.4% for EI and NI respectively. It is concluded that the model can predict nitrate leaching during crop growth.

Application of recharge aquifer media vadose zone and hydraulic conductivity on modeling vulnerability of groundwater to pollution in central rift basins, Kenya

Author: Kemboi, Ezekiel

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 2007

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Hydrology/Geology/Groundwater/Pollution/Lakes/Rift Valley/ ;

Abstract:

Four parameters involving Recharge, aquifer media, Impact of the vadose zone, and hydraulic gonductivity out of the possible seven required by the DRASTIC model have been used to show variation of intrinsic properties of the subsurface and their effect on vulnerability of groundwater to pollution in the Lakes of Nakuru, Elmentaita and Naivasha basins referred as the Central Rift Valley of Kenya. The purpose is to protect groundwater from pollution and manage susceptible areas from anthropogenic effects that might lead to the deterioration of groundwater quality. Modeling has been done using the DRASTIC model approach by employing Arcview 3.3 and Spatial Analyst 2.0 extension. Results show that the two factors which mainly contribute to recharge variation are the amount of the annual rainfall and the distribution of the faults distribution within the rift. The aquifer is seen to be recharged mainly in the eastern part of the study area due to the high rainfall compared to the centre of the rift. The area is arid to semi arid with higher evapo-transpiration rates than rainfall. The presence of faults lines is mainly in the central northern side of the area. This place provides significant recharge rates during periods of high rainfall especially when moisture potential exceeds the gravitational potential of the geologic materials thereby bringing about the infiltration and subsequent percolation of water into the aquifers. The susceptibility of the aquifers to pollution in the areas is generally high in the eastern and northern parts of the area. The contribution of fault lines to vulnerability to pollution is high to the north east of Lake Elmentaita. The susceptibility of aquifer to pollution is mainly restricted to localities in the Naivasha region to the western, eastern and the northwestern parts and to the Aberdares near the Kipipri and Ol Kalou. This is mainly due to the aquifer being mainly of sand, basalt and Lake beds and gravels. Clays are the weathering products of the pyroclastic rocks and the tuffs in the Mau, the western and southern parts of lake Nakuru where it makes up the aquifer media in those localities and thereby have low susceptibility to pollution. Vadose zone variation is almost similar to the aquifer media variation except that the clays are absent in all the strata. Lake beds, gravels and the sediments are mainly in the Ndabibi Maiella and the neigbouring localities are surrounded by the sandy and basaltic aquifers. The greatest portion of the area is covered by rocks of igneous origin which range from rhyolite, ignimbrite, phonolite and pyroclastics. The igneous unsaturated layers are mainly in the Mau escarpment, Njoro, Dundori, Gilgil and part of Narok district to the southwest of the locality. The area is dominated by pyroclastic material and, as a result, the hydraulic conductivity is generally low. The area to the north of the study area has higher vulnerability indices due to the predominance of fluvial material. In the areas where the geology is dominated by basalts, the hydraulic conductivity is also high. The hydrogeological zones vulnerable to pollution are few and widespread.

Concentration levels and patterns of fluoride in groundwater resources from Kendu bay area, Kenya

Author: Okoo, Joyce Atieno

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 2007

Holding Libraries: University of Nairobi Chiromo Library ;

Subject Terms: Water ; Groundwater ; Fluorine ; Kendu Bay area, Kenya ;

Abstract:

Water samples from twenty eight boreholes and twenty six wells were sampled in Kendu Bay area which lies between longitudes 34' 35' and 34' 40' E and latitudes 0' 21' and 0' 27' S. The sampling was done in two seasons: dry season in the month of January 2006 and rainy season in the month of April in the same year. Defficiency or excess of fluoride in drinking water may be harzadous causing dental caries or dental fluorosis respectively. The samples were therefore analysed for fluoride and pH in the laboratory with the aim of determining the concentrations of fluoride in the study area, comparing these concentrations in the rift zone with those outside the rift, hence establish the factors controlling fluoride concentrations in the study area. Ion selective electrode method was used for the fluoride and pH determination in the laboratory. Temperature determinations were done in the field on site of each sampling point and an average of three temperature readings were taken on fresh sample of each sample using a -l00C -1000C range mercury thermometer. Using computer techniques the overall distribution of fluoride levels, temperature and pH values in the study area in different seasons were plotted. The distribution patterns have been explained in terms of geology. These patterns do not change but the concentration chanies. The field and results obtained from the study area were subjected to statistical analysis. The regression curves and values of moment correlation coefficients indicate that there is significant relationship between fluoride and pH in both seasons. Temperature has slight effect on fluoride concentration while there is no relationship between fluoride concentrations and depth. Component factor analysis results show that pH is the parameter that has the highest significant control of fluoride in the study area. Q-Q plot results and the descriptive statistics reveal that fluoride concentrations in the dry season are higher than rainy season, also fluoride concentrations in the lowland are higher than in upland, hence a general pattern in the decrease in the fluoride level from dry season to rainy season. This same pattern applies to temperature and pH. Topographical corrections were done and the elevations obtained in metres were used to determine the groundwater level above sea level. This was used to draw groundwater contours. The groundwater flow within the area of study has been determined by the use of groundwater contours. The flow direction of groundwater is roughly SE-NW -N direction and is the same direction as the surface water. The recharge and discharge areas have also been established from the groundwater contour map. In relation to groundwater flow direction the concentration levels of fluoride are higher in the discharge areas and lower in the recharge areas. Fluoride concentration levels increase with the direction of flow of groundwater. Quality aspect of the groundwater resources in relation to domestic use has been discussed. From this it is established that the waters are not suitable for domestic use.

The distribution of fluoride ions in the groundwaters of the Baringo-Bogoria Lake basin

Author: Mutonga, Marietta W

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 2007

Holding Libraries: University of Nairobi Chiromo Library ;

Subject Terms: Water ; Groundwater ; Flourine ; Baringo-Bogoria Lake Basin ;

Abstract:

ABSTRACT NOT AVAILABLE

The impact of geology and pit latrines on ground water quality of some boreholes,wells and springs in Kwale District Kenya

Author: Mzuga, Jason Mganga

Awarding University: Moi University, Kenya

Level : MPhil

Year: 2007

Holding Libraries: Moi University Margaret Thatcher Library ;

Subject Terms: Kwale District ; Geology ; Groundwater ; Pollution ; Latrines ; Wells ; Boreholes ; Springs ;

Abstract:

Dissolution of rocks and infiltration from pit-latrines can cause pollution of groundwater. In this study, IDS, TSS, conductivity, COD, BOD, dissolved oxygen, calcium, magnesium, sodium, potassium, sulphates, chlorides, fluorides, coliform counts and E. coli as well as pH and temperature, were determined from selected boreholes, springs and wells in Kwale District, underlain by either sandstones or coral limestone. Water samples were taken from each of the water sources between September, 1993 and ovember 1993 which represented the wet season. (Short rains) and between January 1994 and February 1994 which represented the dry season. Data for the two seasons, when compared, showed a slight increase in mean concentrations during the dry season for most parameters i.e. Conductivity, TDS, Cr,.F, CaL+, sulphates with means 706. 7, 487, l75, 0.3, 74,10.4 respectively. The pH showed no change, with a mean of 6.63, while dissolved oxygen, COD, BOD, and coliform counts showed a decrease with means O. 64, 151, l.66 and 160.5 respectively. Analysis using trilinear plots showed the major anions as chlorides and bicarbonates while the major cations are calcium and sodium. The safe distance to locate a pit-latrine from a water source in sandstone regions is recommended to be approximately 120 m, while in limestone regions it is at least 150 m.

A numerical model for simulating the transport of reactive ground water contaminants

Author: Rume, Joshua Sangoro

Awarding University: Kenyatta University, Kenya

Level : MSc

Year: 2006

Holding Libraries: Kenyatta University Moi Library ;

Subject Terms: Groundwater/Water pollution/Hydrology/Mathematical models ;

Abstract:

A contaminant discharged into an aquifer can have a significant impact on the quality of the subsurface water resources. Transported by the groundwater, the contaminant can pollute withdrawal sites at pumping wells, and may reappear at the surface, emerging from springs and seepage faces. Due to the relative inaccessibility of the groundwater and the complexity of the processes involved, it is difficult to predict the extent and impact of the contamination using solely experimental techniques. Numerical modelling has been found to be one of the most effective techniques for predicting the effects, extent and impact of groundwater contamination, remediation and protection of groundwater resources. In this study, a numerical model for simulating the flow and transport of reactive groundwater contaminants has been developed. The flow properties were derived from the Darcy and mass conservation equations that gave velocity distributions required by the contaminant transport equations to determine the spatial and temporal variation of concentration. The governing equations were discretized by integrated finite differences method. The transport equation was solved by operator-splitting technique. The kinetic reaction part was implemented by the linear integrated method. The model was validated using analytical solutions available in literature for uniform velocity cases. The various modules for solving the governing equations were implemented in the object-oriented computer codes. A comparison between model results and analytical solutions show that the numerical solution traits the analytical solution with increasing time. This is attributed to the propagation of the truncation error associated with the numerical method used. Experiments on hydrodynamic control and varying aquifer properties have been done to further show the models usefulness in water quality management. From the hydrodynamic experiment, it was established that it is possible to effectively use a pump-treat and inject strategy to protect a production well from an up-gradient source. Another experiment conducted using the model aimed at predicting the rate of contaminant transport through different aquifer materials. Aquifer materials were characterized by using the values of their hydraulic conductivities obtained from literature. Breakthrough curves were obtained for both continuous and accidental pollution cases. It was found that the rate of contaminant transport process increases with increase in the value of hydraulic conductivity. The numerical model developed will aid in understanding the subsurface flow and transport processes and may also have pedagogic uses especially in the field of groundwater hydrology and engineering.