7 research outputs found
Water Resources Mapping along the Jilango /Shabel-Dulla Areas of Laghdera Subcounty in Northern Kenya
Full text linkThe Jilango and Shabel-Dulla areas are located in the Laghdera Sub- County of Garissa County, in North Eastern Kenya, on the fringes of the distal Merti aquifer. Water scarcity has been the number one factor contributing to the immense levels of poverty in the pastoralist centre. The resident inhabitants are of the nomadic-pastoralist lifestyles, raising livestock such as camels, goats and cows, for upkeep. The settlements are six kilometers apart and this is a deliberate effort by the villagers to live near the seasonal River Jilango, within whose beds the residents have sunk several sand wells to get water for their domestic use, and also, on a limited extent, to get little water for their livestock, mainly the sheep and goats. The water resources quality, ease of availability and priority ranking in the study area were undertaken using field traverse along the river channels and also via geophysical mapping in the selected sites in the neighborhood of the riverbed. Priority ranking was pegged upon the ready availability and cost effective way of getting water into the villages for use, for both domestic- and livestock- watering purposes. In areas where groundwater potential was inferred using Geophysical mapping, it became paramount that the study gets to estimate the water quality expected from the yet-to-be-drilled proposed well points. Groundwater potential estimation was also undertaken using field geophysics and GIS, as well as the Decision Tree algorithms in R software packages. Precision and sensitivity analysis of the data was also undertaken using the python Softwares and returned favorable results for the techniques employed. Feasibility for Wells, Earthpans, Springs and piped water from Baraki Centre were all considered, in terms of how much each option would cost to the community. This involved physical transects and meetings with members of the public in the proposed locality. From the table so prepared, it was decided to rank groundwater as number two priority source, mainly for use by r livestock and an earthpan as number one for human domestic usages, based on water quality and other factors considered. The study shows the priority ranking of water resources in the study area as well as the fact that predicted groundwater quality is of inferior order, and recommends the designing and construction of a big storage dam to aid domestic water supply. This shall complement the available aquifer water which, though saline and of low discharge, can be tolerated by the livestock. Equally deduced from the study is the fact the decision tree algorithm is a useful hydrological assessment tool, as it was used to a degree of over 90 percent precision levels, in predicting the water quality that will be encountered in the locality, once the new well water is drilled
The Decision Tree Aided Neuro-Fuzzy Inference Characterization of the Stochastic Hydrology of the Tana Alluvial Aquifer
Full text linkThe Tana Alluvial Aquifer is the name given to the little-understood aquifer which is active in the areas bordering the River Tana Flow course as the river weaves its way through the sedimentary plains of Balambala, Garissa, Fafi and Ijara and, finally, into the Tana Delta areas, with the common denominator being the proximity to the Lower Tana catchment, especially the riparian corridor of the River itself, and beyond. The aquifer may extend to between five to fifteen kilometers away from the river channels course way, and at times, it may be felt even 20 kilometers away. The geology of the locality is heterogeneous and comprise sediments whose soil mechanics may not be easily deciphered, since some areas close to the river have very fresh water while others are saline (Bura East in Fafi Sub County easily comes to mind here). There are areas far from the river but bearing fresh water (Mulanjo comes to mind). In some areas, sites close to the river discharge low yield figures, whereas those located farther afield discharge favorably. The water quality and discharge are therefore stochastic variables, subject to chance occurrence. In view of this inconsistency, and on the account of data scarcity, the neuro-fuzzy inference algorithm was developed to map the Universe of Discourse of the Tana Alluvial Aquifer, aka the T.A.A., as it relates to the longitudes, latitudes, depths, and discharges of the aquifers in the study area. The mapping was with respect to aquifer discharge, the variable used to characterize an aquifer, in terms of Transmissivity and Hydraulic Conductivity, thereby defining aquifer recharge propensity. Membership functions were developed using the trapezoidal membership family, and fuzzy rules were appropriately evolved from the fuzzified aquifer data, before finally employing the Sugeno inference engines (in Python) to make predictions of discharge, at each of the T.A.A. aquifer subsets mapped for fresh, saline, hard and brackish water species. The accuracy in the outputs achieved in the areas mapped vindicated the power of the neuro-fuzzy inference systems, as the accuracy oscillated between 92 and 99 percent, when the discharge values predicted were compared with the actual known discharge values of the wells mapped. The water quality class characterization was then undertaken using the decision tree (DT) algorithm in python which gave rise to a 100 percent prediction accuracy. The same DT algorithm could not successfully predict the discrete values of aquifer discharge or EC values, with as much accuracy (but performed excellently with salinity class data), and that was why fuzzy logic was employed. The study vindicated the use of the DT and Fuzzy Logic Algorithms as simple, yet powerful analytical tools, in characterizing the Stochastic Hydrology of the Tana Alluvial Aquifer.
Geo-electrical Resistivity Assessment of the Groundwater Resources Potential of the Waradey Area, Eldas Sub-county, North Eastern Kenya
Full text linkThe Waradey Area is located in Eldas subcounty in the greater Wajir County. The area has lacked reliable water structures since independence and was the focus of a concerted geophysical mapping to help avail water to the local populace. To achieve this, Geoelectrical Resistivity Mapping and simulation Models using the GIS techniques were used. This achieved the goals of combining the geophysical models and the hydrogeologic models so generated to build a reliable picture of expectations of the proposed drilling program. The variables simulated using hydrogeologic modeling were aquifer transmissivity, flow-vectors showing direction of movement of water in the subsurface flow systems, salinity, and the aquifer geological material, as well as the water struck levels, which may be used to infer aquifer groundwater levels in the study area. The geoelectrical models were used to simulate fractures, weathering and moisture content of the underground. The IPI2WIN software was used to model the geophysical VES data so generated. When the two models were combined (ie. both geophysical and hydrogeological), a picture of reliable groundwater potential emerged. On the basis of the foregoing, a well was surveyed and was recommended for drilling, to be discharging up to 10 cubic meters per hour. At worst the models projected a discharge of 2-6 cubic meters per hour. The study has shown the reliability of Vertical Electrical Sounding probes and geospatial models, as powerful groundwater exploration tools for the Eldas area, given the limited actual data of hydrogeological drilling in the study locality.
Groundwater Sodium Levels Estimation of Proposed Irrigation Groundwater Source for the Kumahumato Settlement of the Dadaab Subcounty, North Eastern Kenya
Full text linkThe Project Area of Kumahumato is a locality located on the fringes of the Merti aquifer within a radii ranging from 5 to 10 kilometer metric units. The area is primarily inhabited Nomadic pastoralists who have limited experience with matters farming and allied agricultural techniques. Owing to the rapid change in climate patterns and with massive death toll of livestock resulting from prolonged droughts and unpredictable rains, the community leadership have deemed it fit to focus on irrigation-aided agriculture. One problem noted is that the sodium levels in the soils may be exacerbated by irrigation farming, if the groundwater sodic levels area already way above the thresholds deemed safe by the WHO, both for human usage and for soil chemistry. The sodium levels may increase with progressive usage of borehole water in the farming projects, up to a point deemed way beyond salvage-meaning the destroyed fertility may not be reclaimed or restored once the damage is done. To mitigate against the potential disastrous and irreversible consequence, the study team undertook a geophysical surveys as well as hydrochemical surveys and data analysis to understand the likely consequence of a prolonged usage of irrigation –based agriculture in the Kumahumato centre. To achieve this, eight algorithms were employed, namely, Neural Networks, Naïve Bayes, Support Vector Machines, Logistic Regression, Decision Trees, K-Nearest Neighbor and Random forests algorithm amongst others. The final three algorithms mentioned here emerged out as the best performers, registering between 95 to hundred percent precisions levels during detailed data analysis. A point picked at random in the Kumahumato area which showed promise of good groundwater potential was analysed and found to be at suitable aquifer sodium levels, which will not be a threat to small scale agriculture envisaged in the program. Machine Learning was thus employed and proved a useful decision making tool in the Project Planning and Design Phase for the proposed food security meant to be a practical resilience response to climate change hazards
Groundwater Quality Prediction Using Logistic Regression Model for Garissa County
Full text linkGroundwater quality modeling can reduce the cost of exploration and siting of boreholes considerably. The present study applies Logistic Regression Model to predict the probability of siting boreholes of fresh or saline water based on geospatial data such as altitude (m), longitudes, latitudes and depths (m), and geophysical data such as electrical resistivity from 45 exploration sites. The geology of the study area is represented by permeable water-bearing Tertiary-Quaternary sediments located within the Anza Rift. The water bearing zones, or water struck levels, range in depth between 50 and 150 m and the average yield of about 1 - 5 m3 per hour, in the case of old wells done using percussion rigs in the period between 1960s to the 1990s. Recently, the discharge in the wells done using modern mud rotary equipment yields up to 30 m3 per hour, with depths ranging between 200 to 250m below ground level. The modeling results show strong correlation between the dependent variables; depth, mean resistivity, longitudes, and latitudes on one hand, and salinity status of aquifers. It is, therefore, possible to know the water quality of a location in the study area before actual drilling is undertaken. Of all the runs made, 93% were predicted accurately while only 7% of the cases deviated from the predicted quality. These findings prove the usefulness of the LRM in predicting and identifying sites of high groundwater accumulation and groundwater salinity in arid region
ICDP workshop on the Deep Drilling in the Turkana Basin project: exploring the link between environmental factors and hominin evolution over the past 4 Myr
Full text linkScientific drill cores provide unique windows into the processes of the past and present. In the dynamic tectonic, environmental, climatic, and ecological setting that is eastern Africa, records recovered through scientific drilling enable us to look at change through time in unprecedented ways. Cores from the East African Rift System can provide valuable information about the context in which hominins have evolved in one of the key regions of hominin evolution over the past 4 Myr. The Deep Drilling in the Turkana Basin (DDTB) project seeks to explore the impact of several types of evolution (tectonic, climatic, biological) on ecosystems and environments. This includes addressing questions regarding the region's complex and interrelated rifting and magmatic history, as well as understanding processes of sedimentation and associated hydrothermal systems within the East African Rift System. We seek to determine the relative impacts of tectonic and climatic evolution on eastern African ecosystems. We ask the follow questions: what role (if any) did climate change play in the evolution of hominins? How can our understanding of past environmental change guide our planning for a future shaped by anthropogenic climate change?
To organize the scientific community's goals for deep coring in the Turkana Basin, we hosted a 4 d ICDP supported workshop in Nairobi, Kenya, in July 2022. The team focused on how a 4 Myr sedimentary core from the Turkana Basin will uniquely address key scientific research objectives related to basin evolution, paleoclimate, paleoenvironment, and modern resources. Participants also discussed how DDTB could collaborate with community partners in the Turkana Basin, particularly around the themes of access to water and education. The team concluded that collecting the proposed Pliocene to modern record is best accomplished through a two-phase drilling project with a land-based transect of four cores spanning the interval from 4 Ma to the Middle–Late Pleistocene (< 0.7 Ma) and a lake-based core targeting the interval from ∼ 1 Ma to present. The second phase, while logistically more challenging due to the lack of drilling infrastructure currently on Lake Turkana, would revolutionize our understanding of a significant interval in the evolution and migration of Homo sapiens for a time period not currently accessible from the Kenyan part of the Turkana Basin. Collectively, the DDTB project will provide exceptional tectonic and climatic data directly associated with one of the world's richest hominin fossil localities.</p
ICDP workshop on the Deep Drilling in the Turkana Basin project:Exploring the link between environmental factors and hominin evolution over the past 4 Myr
Full text linkScientific drill cores provide unique windows into the processes of the past and present. In the dynamic tectonic, environmental, climatic, and ecological setting that is eastern Africa, records recovered through scientific drilling enable us to look at change through time in unprecedented ways. Cores from the East African Rift System can provide valuable information about the context in which hominins evolved in one of the key regions of hominin evolution over the past 4 Myr. The Deep Drilling in the Turkana Basin (DDTB) project seeks to explore the impact of several types of evolution (tectonic, climatic, biological) on ecosystems and environments. This includes addressing questions regarding the region’s complex and interrelated rifting and magmatic history, as well as understanding processes of sedimentation and associated hydrothermal systems within the East African Rift System. We seek to determine the relative impacts of tectonic and climatic evolution on eastern African ecosystems. We ask, what role (if any) did climate change play in the evolution of hominins? How can our understanding of past environmental change guide our planning for a future shaped by anthropogenic climate change? To organize the scientific community’s goals for deep coring in the Turkana Basin, we hosted a 4-day ICDP supported workshop in Nairobi, Kenya in July 2022. The team focused on how a 4 Myr sedimentary core from the Turkana Basin will uniquely address key scientific research objectives related to basin evolution, paleoclimate, paleoenvironment, and modern resources. Participants also discussed how DDTB could collaborate with community partners in the Turkana Basin, particularly around the themes of access to water and education. The team concluded that collecting the proposed Pliocene to modern record is best accomplished through a 2-phase drilling project with a land-based transect of four cores spanning the interval from 4 Ma to Middle/Late Pleistocene (<0.7 Ma) and a lake-based core targeting the interval from ~1 Ma to present. The second phase, while logistically more challenging due to the lack of drilling infrastructure currently on Lake Turkana, would revolutionize our understanding of a significant interval in the evolution and migration of Homo sapiens for a time period not currently accessible from the Kenyan part of the Turkana Basin. Collectively, the DDTB project will provide exceptional tectonic and climatic data directly associated with one of the world’s richest hominin fossil localities
