Publications


Submitted

Omuombo, C, Odada EO, Olago DO.  Submitted.  Coastal Erosion: A Natural Outlook-Geonvironmental Resources and Hazards. Abstract

This chapter focuses on the existing information on the hydrodynamics and sediment transport processes along the Kenyan coastline. Although the low-lying coastline is under threat from coastal erosion that has led to its destabilization, the factors are linked to local and global processes. Changes in land used for agriculture have led to increase sediment fluxes which have resulted in increase in turbidity and siltation. Other activities such as coral and mangrove harvesting, seawall construction, urbanization and lack of regulations on the construction of structures along of the coastline can be linked to the coastal erosion processes. Among the global factors, the Kenyan coastline has been affected by the extreme events such as the El Niño event of 1997/1998, which led to devastating effects such as an increase in sediment fluxes and turbidity, coral bleaching and mortality and substantial sea level rise. A 1.3 °C sea surface temperature rise on the western side of the Indian Ocean has been recorded since 1880; this makes the coastline vulnerable to the impacts of the predicted 6 °C temperature rise in East Africa due to climate change. It is estimated that the biggest coastal city of Mombasa will be 17% submerged by 2100 and the Tana delta will experience a 5% loss as a consequence of climate change due to the frequent storms that are anticipated. Although the 2004 global tsunami events did not have devastating effects on the Kenyan coast, the event hit the coastline at low tide and this led to the limited damage. In the management of the shoreline, currently an Integrated Coastal Zone Management strategy does not exist although efforts are underway to develop a shoreline management strategy that incorporates the principles of the integration in the management of the coastline. These efforts are encouraged by the success of the marine protected areas of Malindi and Watamu and the current co-management strategy adapted by the Ministry of Fisheries through the Beach Management Units that engages the resource users as equal partners in the management of the coastal resources.
Keywords

Urbanization;
Sediment flux;
El Niño;
Sea surface temperature;
Tsunami;
Mombasa;
Tana delta;
Marine protected areas;
Beach Management Units

2018

Amadi, JA, Olago DO, Ong’amo GO, Oriaso SO, Nyamongo IK, Estambale BBA.  2018.  “We don’t want our clothes to smell smoke”: changing malaria control practices and opportunities for integrated community-based management in Baringo, Kenya. BMC public health. 18(1):609. AbstractFull Text

Background

The decline in global malaria cases is attributed to intensified utilization of primary vector control interventions and artemisinin-based combination therapies (ACTs). These strategies are inadequate in many rural areas, thus adopting locally appropriate integrated malaria control strategies is imperative in these heterogeneous settings. This study aimed at investigating trends and local knowledge on malaria and to develop a framework for malaria control for communities in Baringo, Kenya.

Methods

Clinical malaria cases obtained from four health facilities in the riverine and lowland zones were used to analyse malaria trends for the 2005–2014 period. A mixed method approach integrating eight focus group discussions, 12 key informant interviews, 300 survey questionnaires and two stakeholders’ consultative forums were used to assess local knowledge on malaria risk and develop a framework for malaria reduction.

Results

Malaria cases increased significantly during the 2005–2014 period (tau = 0.352; p < 0.001) in the riverine zone. March, April, May, June and October showed significant increases compared to other months. Misconceptions about the cause and mode of malaria transmission existed. Gender-segregated outdoor occupation such as social drinking, farm activities, herding, and circumcision events increased the risk of mosquito bites. A positive relationship occurred between education level and opinion on exposure to malaria risk after dusk (χ2 = 2.70, p < 0.05). There was over-reliance on bed nets, yet only 68% (204/300) of respondents owned at least one net. Complementary malaria control measures were under-utilized, with 90% of respondents denying having used either sprays, repellents or burnt cow dung or plant leaves over the last one year before the study was conducted. Baraza, radios, and mobile phone messages were identified as effective media for malaria information exchange. Supplementary strategies identified included unblocking canals, clearing Prosopis bushes, and use of community volunteers and school clubs to promote social behaviour change.

Conclusions

The knowledge gap on malaria transmission should be addressed to minimize the impacts and enhance uptake of appropriate malaria management mechanisms. Implementing community-based framework can support significant reductions in malaria prevalence by minimizing both indoor and outdoor malaria transmissions.

Keywords

Local knowledgeMalaria trendsCommunity-based strategiesFramework

Muhati, GL, Olago D, Olaka L.  2018.  Participatory scenario development process in addressing potential impacts of anthropogenic activities on the ecosystem services of MT. Marsabit forest, Kenya. Global Ecology and Conservation. 14(April 2018):e00402. AbstractFull Text

The Marsabit Forest Reserve (MFR), a green island in an arid environmental setting, generates multiple ecosystem goods and services (ES) to the local community critical for their livelihoods. The forest has been experiencing substantial land conversion for town expansion, agriculture production and settlements threatening long-term ES provision. Sustaining the forest ES under increasing anthropogenic pressures is one of the great challenges of the Marsabit forest community. We used focus group discussions in the thirteen locations around the forest and individual key informant's interviews in the identification of drivers of change and their potential impacts on ES in MFR. We used the scenario development process (SDP) in coming up with four divergent but plausible exploratory scenarios. The study established that the main ES provided by the forest was, water, fuelwood, forage (dry season grazing resource), medicinal plants and timber for construction. Stakeholders identified population pressure, unsustainable utilisation of forest resources, institutional barriers to effective resource management, land use and climate change as the main drivers impacting ES provision in the forest. Land use change and climate change were considered the most significant drivers yet the most uncertain in the future impacting ES provision in the MFR. The SDP identified four alternative future scenarios for the MFR by the year 2043 with the Marsabit we want scenario identified as the most desirable future for the sustainable supply of ES with adequate adaptation to observed changes. Stakeholders came up with a joint action plan implementation matrix for the identified scenario while mitigating the negative aspects of the alternative scenarios. The results support the need for participatory land use planning that takes into to account the growing threat of climate change to natural forest systems.

Muhati, GL, Olago D, Olaka L.  2018.  Quantification of carbon stocks in Mount Marsabit Forest Reserve, a sub-humid montane forest in northern Kenya under anthropogenic disturbance. Global Ecology and Conservation. 14 AbstractWebsite

The quantification of carbon stocks is vital for decision making in forest management, carbon stock change assessment and scientific applications. We applied the land degradation surveillance framework (LDSF) method with a sentinel site of (10 km × 10 km) to assess carbon stock levels and tree diversity in the Marsabit Forest Reserve (MFR). The above ground (ABG) carbon stock was estimated at 12.42 t/ha, while soil organic carbon (SOC) was 12.51 t/ha, with SOC densities increasing with increasing depth. The mean ABG carbon and SOC densities were higher in the least disturbed strata than the disturbed strata. The estimated ABG carbon and SOC stocks were significantly lower than the range observed in a typical dry tropical forest. Twenty-one tree species were recorded belonging to twelve families with the disturbed areas recording nine tree species while the least disturbed recording twelve species. Rubiaceae and Rutaceae were the richest families with four species each while Boraginaceae, Capparaceae, Flacourtiaceae, Tiliaceae, Violaceae, and Ochnaceae the least frequent with one species each. The most common tree species were, Croton megalocarpus, Drypetes gerrardii, Ochna insculpta, Strychnos henningsii and Vangueria madagascariensis. The forest recorded a basal diameter of 14.09 ± 12.15 cm, basal area of 0.016 m 2/ha with a mean height of 8.69 m. The basal size class distribution declined monotonically indicative of a stable population. Livestock grazing, selective logging, and firewood collection were the primary forms of anthropogenic activities recorded in the MFR despite the moratorium imposed on consumptive utilisation of forest products by the Marsabit County security committee. The Pearson correlation coefficient returned an inverse relationship between forest disturbance with SOC and ABG carbon in the disturbed strata suggesting that anthropogenic activities reduced carbon stocks in the MFR. Concerted efforts to mitigate anthropogenic impacts on the MFR could significantly increase its terrestrial carbon sequestration potential and the provision of critical ecosystem goods and services.

Olago, D, Marchant R, Richer S, Capitani C, Courtney-Mustaphi C, Prendergast M.  2018.  Drivers and trajectories of land cover change in East Africa: Human and environmental interactions from 6000years ago to present. Earth-Science Reviews. 178:322-378. AbstractFull Text

East African landscapes today are the result of the cumulative effects of climate and land-use change over millennial timescales. In this review, we compile archaeological and palaeoenvironmental data from East Africa to document land-cover change, and environmental, subsistence and land-use transitions, over the past 6000 years. Throughout East Africa there have been a series of relatively rapid and high-magnitude environmental shifts characterised by changing hydrological budgets during the mid- to late Holocene. For example, pronounced environmental shifts that manifested as a marked change in the rainfall amount or seasonality and subsequent hydrological budget throughout East Africa occurred around 4000, 800 and 300 radiocarbon years before present (yr BP). The past 6000 years have also seen numerous shifts in human interactions with East African ecologies. From the mid-Holocene, land use has both diversified and increased exponentially, this has been associated with the arrival of new subsistence systems, crops, migrants and technologies, all giving rise to a sequence of significant phases of land-cover change. The first large-scale human influences began to occur around 4000 yr BP, associated with the introduction of domesticated livestock and the expansion of pastoral communities. The first widespread and intensive forest clearances were associated with the arrival of iron-using early farming communities around 2500 yr BP, particularly in productive and easily-cleared mid-altitudinal areas. Extensive and pervasive land-cover change has been associated with population growth, immigration and movement of people. The expansion of trading routes between the interior and the coast, starting around 1300 years ago and intensifying in the eighteenth and nineteenth centuries CE, was one such process. These caravan routes possibly acted as conduits for spreading New World crops such as maize (Zea mays), tobacco (Nicotiana spp.) and tomatoes (Solanum lycopersicum), although the processes and timings of their introductions remains poorly documented. The introduction of southeast Asian domesticates, especially banana (Musa spp.), rice (Oryza spp.), taro (Colocasia esculenta), and chicken (Gallus gallus), via transoceanic biological transfers around and across the Indian Ocean, from at least around 1300 yr BP, and potentially significantly earlier, also had profound social and ecological consequences across parts of the region.

Through an interdisciplinary synthesis of information and metadatasets, we explore the different drivers and directions of changes in land-cover, and the associated environmental histories and interactions with various cultures, technologies, and subsistence strategies through time and across space in East Africa. This review suggests topics for targeted future research that focus on areas and/or time periods where our understanding of the interactions between people, the environment and land-cover change are most contentious and/or poorly resolved. The review also offers a perspective on how knowledge of regional land-use change can be used to inform and provide perspectives on contemporary issues such as climate and ecosystem change models, conservation strategies, and the achievement of nature-based solutions for development purposes.

Olago, D, Siderius C, Gannon KE, Ndiyoi M, Opere A, Batisani N, Pardoe J, Conway D.  2018.  Hydrological response and complex impact pathways of the 2015/2016 El Niño in Eastern and Southern Africa. Earth's Future. 6(1):2-22. AbstractFull Text

The 2015/2016 El Niño has been classified as one of the three most severe on record. El Niño teleconnections are commonly associated with droughts in southern Africa and high precipitation in eastern Africa. Despite their relatively frequent occurrence, evidence for their hydrological effects and impacts beyond agriculture is limited. We examine the hydrological response and impact pathways of the 2015/2016 El Niño in eastern and southern Africa, focusing on Botswana, Kenya, and Zambia. We use in situ and remotely sensed time series of precipitation, river flow, and lake levels complemented by qualitative insights from interviews with key organizations in each country about awareness, impacts, and responses. Our results show that drought conditions prevailed in large parts of southern Africa, reducing runoff and contributing to unusually low lake levels in Botswana and Zambia. Key informants characterized this El Niño through record high temperatures and water supply disruption in Botswana and through hydroelectric load shedding in Zambia. Warnings of flood risk in Kenya were pronounced, but the El Niño teleconnection did not materialize as expected in 2015/2016. Extreme precipitation was limited and caused localized impacts. The hydrological impacts in southern Africa were severe and complex, strongly exacerbated by dry antecedent conditions, recent changes in exposure and sensitivity and management decisions. Improved understanding of hydrological responses and the complexity of differing impact pathways can support design of more adaptive, region‐specific management strategies.

2017

Olag, D, Wolff C, Verschuren D, Daele MEV, Waldmann N, Meyer I, Lane CS, der Meeren VT, Ombori T, Kasanzu C.  2017.  ICDP Project DeepCHALLA: Reconstructing 250,000 Years of Climate Change and Environmental History on the East African Equator. AGU Fall Meeting Abstracts. AbstractFull Text

Sediments on the bottom of Lake Challa, a 92-m deep crater lake on the border of Kenya and Tanzania near Mt. Kilimanjaro, contain a uniquely long and continuous record of past climate and environmental change in easternmost equatorial Africa. Supported in part by the International Continental Scientific Drilling Programme (ICDP), the DeepCHALLA project has now recovered this sediment record down to 214.8 m below the lake floor, with 100% recovery of the uppermost 121.3 m (the last 160 kyr BP) and ca.85% recovery of the older part of the sequence, down to the lowermost distinct reflector identified in seismic stratigraphy. This acoustic basement represents a ca.2-m thick layer of coarsely laminated, diatom-rich organic mud mixed with volcanic sand and silt deposited 250 kyr ago, overlying an estimated 20-30 m of unsampled lacustrine deposits representing the earliest phase of lake development. Down-hole logging produced profiles of in-situ sediment composition that confer an absolute depth- scale to both the recovered cores and the seismic stratigraphy. An estimated 74% of the recovered sequence is finely laminated (varved), and continuously so over the upper 72.3 m (the last 90 kyr). All other sections display at least cm-scale lamination, demonstrating persistence of a tranquil, profundal depositional environment throughout lake history. The sequence is interrupted only by 32 visible tephra layers 2 to 9 mm thick; and by several dozen fine-grained turbidites up to 108 cm thick, most of which are clearly bracketed between a non-erosive base and a diatom-laden cap. Tie points between sediment markers and the corresponding seismic reflectors support a preliminary age model inferring a near-constant rate of sediment accumulation over at least the last glacial cycle (140 kyr BP to present). This great time span combined with the exquisite temporal resolution of the Lake Challa sediments provides great opportunities to study past tropical climate dynamics at both short (inter-annual to decadal) and long (glacial-interglacial) time scales; and to assess the multi-faceted impact of this climate change on the region's freshwater resources, the functioning of terrestrial ecosystems, and the history of the African landscape in which modern humans (our species, Homo sapiens) originally evolved and have lived ever since.

Olago, D, Sier MJ, Langereis CG, Dupont-Nivet G, Feibel CS, Joordens JCA, et al.  2017.  The top of the Olduvai Subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, hominin sites and Paleolakes Drilling Project (HSPDP). Quaternary Geochronology. 42:117-129. AbstractFull Text

One of the major challenges in understanding the evolution of our own species is identifying the role climate change has played in the evolution of hominin species. To clarify the influence of climate, we need long and continuous high-resolution paleoclimate records, preferably obtained from hominin-bearing sediments, that are well-dated by tephro- and magnetostratigraphy and other methods. This is hindered, however, by the fact that fossil-bearing outcrop sediments are often discontinuous, and subject to weathering, which may lead to oxidation and remagnetization. To obtain fresh, unweathered sediments, the Hominin Sites and Paleolakes Drilling Project (HSPDP) collected a ∼216-meter core (WTK13) in 2013 from Early Pleistocene Paleolake Lorenyang deposits in the western Turkana Basin (Kenya). Here, we present the magnetostratigraphy of the WTK13 core, providing a first age model for upcoming HSPDP paleoclimate and paleoenvrionmental studies on the core sediments. Rock magnetic analyses reveal the presence of iron sulfides carrying the remanent magnetizations. To recover polarity orientation from the near-equatorial WTK13 core drilled at 5°N, we developed and successfully applied two independent drill-core reorientation methods taking advantage of (1) the sedimentary fabric as expressed in the Anisotropy of Magnetic Susceptibility (AMS) and (2) the occurrence of a viscous component oriented in the present day field. The reoriented directions reveal a normal to reversed polarity reversal identified as the top of the Olduvai Subchron. From this excellent record, we find no evidence for the ‘Vrica Subchron’ previously reported in the area. We suggest that outcrop-based interpretations supporting the presence of the Vrica Subchron have been affected by the oxidation of iron sulfides initially present in the sediments -as evident in the core record- and by subsequent remagnetization. We discuss the implications of the observed geomagnetic record for human evolution studies.

Olago, D, Verschuren D, Daele MV, Wolff C, Waldmann N.  2017.  ICDP project DeepCHALLA: reconstructing East African climate change and environmental history over the past 250,000 years, April, 2017. 19th EGU General Assembly, EGU2017. , Vienna, Austria Abstract

Sediments on the bottom of Lake Challa, a 92-meter deep crater lake on the border of Kenya and Tanzania near Mt. Kilimanjaro, contain a uniquely long and continuous record of past climate and environmental change. The near-equatorial location and exceptional quality of this natural archive provide great opportunities to study tropical climate variability at both short (inter-annual to decadal) and long (glacial-interglacial) time scales; and the influence of this climate variability on the region's freshwater resources, the functioning of terrestrial ecosystems, and the history of the East African landscape in which modern humans (our species, Homo sapiens) evolved and have lived ever since. Supported in part by the International Continental Scientific Drilling Programme (ICDP), the DeepCHALLA project has now recovered the sediment record of Lake Challa down to 214.8 meter below the lake floor, with almost certain 100% cover of the uppermost 121.3 meter (ca.150,000 year BP to present) and estimated 85% cover over the lower part of the sequence, down to the lowermost distinct reflector in the available seismic stratigraphy. This reflector represents a 2 meter thick layer of volcanic sand and silt deposited ca.250,000 years ago, and overlies still older silty lacustrine clays deposited during early lake development. Down-hole logging produced continuous profiles of in-situ sediment composition that confer an absolute depth scale to both the recovered cores and their three-dimensional representation in seismic stratigraphy. As readily observed through the transparent core liners, Lake Challa sediments are finely laminated throughout most of the recovered sequence. Combined with the great time span, the exquisite temporal resolution of these sediments promises to greatly increase our understanding of tropical climate and ecosystem dynamics, and create a long-awaited equatorial counterpart to the high-latitude climate records extracted from the ice sheets of Greenland and Antarctica.

Olago, D, Karuri HW, Neilson R, Njeri E, Opere A, Ndegwa P.  2017.  Plant parasitic nematode assemblages associated with sweet potato in Kenya and their relationship with environmental variables. Tropical Plant Pathology. 42(1):1-12. AbstractFull Text

Sweet potato is one of the most important staple food crops consumed in Kenya and throughout Africa but yields are greatly reduced by plant parasitic nematodes (PPN). The aim of this study was to determine the prevalence of PPN in Kenyan sweet potato fields and their relationship with soil and climatic variables. Soil samples were collected from sweet potato fields in Busia, Teso, Kisii, Embu and Makueni counties. Thirteen nematode genera were identified across the five counties with Meloidogyne, Pratylenchus and Rotylenchus being the most prevalent. There was a significant (P <0.05) relationship between PPN abundance and sodium, calcium and iron. Canonical correspondence analysis of climatic variables revealed that the relationship between rainfall and nematode genera was significant (P <0.05) while maximum and minimum temperatures were not significant. This description of PPN assemblages associated with sweet potato in Kenya and their relationship with environmental variables provides a starting point from which appropriate nematode management strategies can be implemented.

Olago, D, Karuri HW, Neilson R, Mararo E, Villinger J.  2017.  A survey of root knot nematodes and resistance to Meloidogyne incognita in sweet potato varieties from Kenyan fields. Crop protection. 92:114-121. AbstractFull Text

The root knot nematode, Meloidogyne is one of the most economically damaging plant parasitic nematode groups, and are widely distributed in Kenyan agro-ecosystems. The aim of this study was to determine the diversity of Meloidogyne species in Kenyan sweet potato fields and identify sweet potato varieties that exhibit resistance to M. incognita. Meloidogyne species were collected from Nyanza, Western, Eastern and Central Provinces of Kenya. Mitochondrial DNA was used to differentiate Meloidogyne species. The most common species in all sampled regions was M. incognita. Meloidogyne hapla was recorded for the first time in Kenyan sweet potato growing areas (Mosocho, Matayos, Teso South, Manyatta, and Nzaui sub-counties), while M. enterolobii was observed in Kiharu, Matayos and Mosocho sub-counties and a novel Meloidogyne sp. was identified in Kiharu sub-county. Seventy-two sweet potato varieties collected from both agricultural fields and research stations in Kenya were evaluated for resistance to M. incognita under greenhouse conditions in two separate trials. Known susceptible (Beauregard) and resistant (Tanzania) sweet potato varieties were included as controls. Responses of sweet potato varieties to M. incognita infection was assessed by the number of eggs present and level of galling on a scale of 1–5, where 0 = 0 galls and 5 ≥ 100 galls. The reproduction index (RI) was used to classify the varieties as resistant or susceptible. There was a significant difference (P < 0.001) in the number of eggs, GI and RI among the varieties tested. Forty nine sweet potato varieties were considered very resistant and may be used in breeding programs to incorporate resistance against M. incognita into commercial cultivars of sweet potato or to use them in crop rotation programmes for management of RKN. The results on Meloidogyne species diversity in Kenyan sweet potato fields will also be useful in nematode management programs

Olago, D, Campisano CJ, Cohen AS, Arrowsmith RJ, Asrat A, Behrensmeyer AK, et al.  2017.  The Hominin Sites and Paleolakes Drilling Project: High-Resolution Paleoclimate Records from the East African Rift System and Their Implications for Understanding the Environmental Context of Hominin Evolution. Paleo Anthropology. 1:43. Abstract2017_campisano_et_al._hspdp_drilling_paper.pdfFull Text

The possibility of a causal relationship between Earth history processes and hominin evolution in Africa has been the subject of intensive paleoanthropological research for the last 25 years. One fundamental question is: can any geohistorical processes, in particular, climatic ones, be characterized with sufficient precision to enable temporal correlation with events in hominin evolution and provide support for a possible causal mechanism for evolutionary changes? Previous attempts to link paleoclimate and hominin evolution have centered on evidence from the outcrops where the hominin fossils are found, as understanding whether and how hominin populations responded to habitat change must be examined at the local basinal scale. However, these outcrop records typically provide incomplete, low-resolution climate and environmental histories, and surface weathering often precludes the application of highly sensitive, state-of-the-art paleoenvironmental methods. continuous and well-preserved deep-sea drill core records have provided an alternative approach to reconstructing the context of hominin evolution, but have been collected at great distances from hominin sites and typically integrate information over vast spatial scales. The goal of the Hominin Sites and Paleolakes Drilling Project (HSPDP) is to analyze climate and other Earth system dynamics using detailed paleoenvironmental data acquired through scientific drilling of lacustrine depocenters at or near six key paleoanthropological sites in Kenya and Ethiopia. This review provides an overview of a unique collaboration of paleoanthropologists and earth scientists who have joined together to explicitly explore key hypotheses linking environmental history and mammalian (including hominin) evolution and potentially develop new testable hypotheses. With a focus on continuous, high-resolution proxies at timescales relevant to both biological and cultural evolution, the HSPDP aims to dramatically expand our understanding of the environmental history of eastern Africa during a significant portion of the Late Neogene and Quaternary, and to generate useful models of long-term environmental dynamics in the region.

Olago, D, Loomis SE, Russell JM, Verschuren D, Morrill C, Cort GD, et al.  2017.  The tropical lapse rate steepened during the Last Glacial Maximum. Science advances. 3(1):e1600815. AbstractFull text

The gradient of air temperature with elevation (the temperature lapse rate) in the tropics is predicted to become less steep during the coming century as surface temperature rises, enhancing the threat of warming in high-mountain environments. However, the sensitivity of the lapse rate to climate change is uncertain because of poor constraints on high-elevation temperature during past climate states. We present a 25,000-year temperature reconstruction from Mount Kenya, East Africa, which demonstrates that cooling during the Last Glacial Maximum was amplified with elevation and hence that the lapse rate was significantly steeper than today. Comparison of our data with paleoclimate simulations indicates that state-of-the-art models underestimate this lapse-rate change. Consequently, future high-elevation tropical warming may be even greater than predicted.

2016

Olago, D, Joordens J, Beck C, Sier M, der Lubbe JV, et al.  2016.  Climate-driven lacustrine dynamics from the Early Pleistocene Lorenyang Lake, Turkana Basin, Kenya, 17-22 April, 201. EGU General Assembly 2016. , Vienna Austria Abstract

Two stratigraphic records from Kaitio in West Turkana, Kenya, span 1.87 - 1.34 Ma, and document environmental character and variability through a critical interval for human evolution and cultural development. The WTK13 core collected by the Hominin Sites and Paleolakes Drilling Project (HSPDP) recovered 216 m of sediment at 95% recovery. A parallel outcrop record of 180 m was investigated in exposures along the Kaitio laga close to the drill site. Six tephrostratigraphic markers, the Chari, Lokapetamoi, 22Q-3, Etirr, Ebei and KBS Tuffs are present in the outcrop and/or core. These were characterized by single-shard geochemical analysis, and provide links to the well-established tephrochronology of the Turkana Basin. Magnetic polarity stratigraphy of the two records documents the top of the Olduvai Subchron (C2N) at 1.78 Ma. The lithostratigraphic record, bolstered by magnetic susceptibility and sedimentary facies characterization, demonstrates a first-order transition from a deeper lacustrine system to a dynamic lake margin setting, followed by delta progradation. Facies analysis reveals repeated fluctuations of lake level at Milankovitch and sub-Milankovitch scales. Core-outcrop correlation allows detailed comparisons between diagenetically-prone outcrop samples and more pristine samples from the deep core. The excellent preservation of the core sediments makes it possible to obtain critical climate records of organic biomarkers, pollen, phytoliths and other proxies. This detailed archive of environmental variability is closely linked to the rich paleontological and archaeological discoveries from nearby sites and around the Turkana Basin.

Olago, D, Ferrer N, Folch A, Lane M, Thomas M, Sasaka W, et al.  2016.  First step to understand the importance of new deep aquifer pumping regime in groundwater system in a developing country, Kwale, Kenya.. EGU General Assembly Conference Abstracts. 18:16969. AbstractFull Text Link

The population growth in the world carries on the one hand, an increased demand of fresh water and on the other hand, a decrease of quality and quantity of this resource. To avoid this deterioration it is essential doing a good management of surface water and groundwater, specially the second one, which has become the major source of water supply for domestic, industrial and agricultural sectors of many countries (UNEP 1999). This groundwater management starts with an accurate hydrogeological characterization of aquifer systems, mainly in that aquifer systems in which is changing the abstraction regime. In this context of population growth and new abstraction regimes on aquifer system is where the project "Gro for Good: Groundwater Risk for Growth and Development" is founded by UPGro. This interdisciplinary project has the main goal to design, test and transfer to the society an innovative Groundwater Risk Management Tool to improve and get by new governance transformations the balance between economic growth, groundwater sustainability (in terms of quality and quantity) and human development (http://upgro.org/consortium/gro-for-good/). The study area is located on the south eastern coast of Kenya, in Kwale County. The Kwale coastal groundwater system formed by a shallow and deep aquifer systems has long served urban water demands and an established tourism industry but now faces unprecedented ground and surface water resource demands especially from KISCOL's (5,500 hectares of irrigated sugarcane) and the country's largest mining operation (Base Titanium Ltd.). Despite both companies have drilled deep boreholes around the study area (416 km2) to extract groundwater from deep aquifer; no major pumping activity has started yet, allowing baseline evaluation. Scattered around the study are 440 handpumps providing drinking water to over 90,000 people. The relationship between the shallow and deep aquifers remains uncertain and so, the future influence on groundwater level and its quality either. So, in order to define the system and start to understand the different complex interactions, we present the initial results of the first complete water sampling field campaign (September 2015). Water isotope data and major ions were analyzed from 78 shallow and deep wells and surface water spread around study area. This field survey has been useful to understand the recharge, discharge areas and groundwater quality of deep aquifer system and which will have an important role for sustainable water management in the of Kwale area. Acknowledgements The research is primarily supported under the NERC/ESRC/DFID Unlocking the Potential of Groundwater for the Poor (UPGro) as a Catalyst Grant (NE/L001950/1) with work extending until 2019 as a Consortium Grant (NE/M008894/1), see http://www.upgro.org. Data for the paper will be publicly posted on the National Geoscience Data Centre and the UK Data Archive under the terms of the UPGro data management agreement.

Olago, DO, Olaka LA, Wilke FDH, Odada EO, Mulch A, Musolff A.  2016.  Groundwater fluoride enrichment in an active rift setting: Central Kenya Rift case study. Science of the Total Environment. 545:641-653. AbstractFull Text Link

Groundwater is used extensively in the Central Kenya Rift for domestic and agricultural demands. In these active rift settings groundwater can exhibit high fluoride levels. In order to address water security and reduce human exposure to high fluoride in drinking water, knowledge of the source and geochemical processes of enrichment are required. A study was therefore carried out within the Naivasha catchment (Kenya) to understand the genesis, enrichment and seasonal variations of fluoride in the groundwater. Rocks, rain, surface and groundwater sources were sampled for hydrogeochemical and isotopic investigations, the data was statistically and geospatially analyzed. Water sources have variable fluoride concentrations between 0.02–75 mg/L. 73% exceed the health limit (1.5 mg/L) in both dry and wet seasons. F− concentrations in rivers are lower (0.2–9.2 mg/L) than groundwater (0.09 to 43.6 mg/L) while saline lake waters have the highest concentrations (0.27–75 mg/L). The higher values are confined to elevations below 2000 masl. Oxygen (δ18O) and hydrogen (δD) isotopic values range from − 6.2 to + 5.8‰ and − 31.3 to + 33.3‰, respectively, they are also highly variable in the rift floor where they attain maximum values. Fluoride base levels in the precursor vitreous volcanic rocks are higher (between 3750–6000 ppm) in minerals such as cordierite and muscovite while secondary minerals like illite and kaolinite have lower remnant fluoride (< 1000 ppm). Thus, geochemical F− enrichment in regional groundwater is mainly due to a) rock alteration, i.e. through long residence times and natural discharge and/or enhanced leakages of deep seated geothermal water reservoirs, b) secondary concentration fortification of natural reservoirs through evaporation, through reduced recharge and/or enhanced abstraction and c) through additional enrichment of fluoride after volcanic emissions. The findings are useful to help improve water management in Naivasha as well as similar active rift setting environments.

Olago, D, Russell JM, Verschuren D, Kelly MA, Loomis SE, Jackson MS, Morrill C, Damsté SJS, et al.  2016.  Late Pleistocene temperature, hydrology, and glaciation in equatorial East Africa. American Geophysical Union, Fall General Assembly 2016. AbstractFull Text Link

In the coming century the world's high tropical mountains are predicted to experience a magnitude of climate change second only to the Arctic due to amplification of warming with elevation in the tropics. Proxy data suggest that substantial changes in tropical temperature and hydroclimate also occurred during the last deglaciation, the most recent time period when rising atmospheric CO2 concentrations caused large changes in global climate. Determining whether the rate of temperature change with elevation (the lapse rate) was different from today during the Last Glacial Maximum (LGM) is therefore critical to understanding the future of tropical mountain environments and resources. Here we present a new 25,000-year temperature reconstruction based upon organic geochemical analyses of sediment cores from Lake Rutundu (3,078 m asl), Mount Kenya, East Africa. Through comparison with regional reconstructions of lower elevation temperature, we show that LGM cooling was amplified with elevation and hence that the lapse rate was significantly steeper than today. Comparison of our lapse rate reconstructions with equilibrium line altitude reconstructions from glacial moraines indicates that temperature, rather than precipitation, was the dominant control on tropical alpine glacier fluctuations at this time scale. Nevertheless, our results have important implications for the tropical hydrological cycle, as changes in the lapse rate are intimately linked with changes in atmospheric water vapour concentrations. Indeed, we attribute the steeper lapse rate to drying of the tropical ice-age atmosphere, a hypothesis supported by palaeoclimate models. However, comparison of our data to these simulations indicates that state-of-the-art models significantly underestimate tropical temperature changes at high elevation and therefore the lapse-rate change. Consequently, future high-elevation tropical warming may be even greater than currently predicted.

Olago, D, Ochieng AO, Nanyingi M, Kipruto E, Ondiba IM, Amimo FA, et al.  2016.  Ecological niche modelling of Rift Valley fever virus vectors in Baringo, Kenya. Infection ecology & epidemiology. 6(1):32322. AbstractWebsite

BACKGROUND:

Rift Valley fever (RVF) is a vector-borne zoonotic disease that has an impact on human health and animal productivity. Here, we explore the use of vector presence modelling to predict the distribution of RVF vector species under climate change scenario to demonstrate the potential for geographic spread of Rift Valley fever virus (RVFV).
OBJECTIVES:

To evaluate the effect of climate change on RVF vector distribution in Baringo County, Kenya, with an aim of developing a risk map for spatial prediction of RVF outbreaks.
METHODOLOGY:

The study used data on vector presence and ecological niche modelling (MaxEnt) algorithm to predict the effect of climatic change on habitat suitability and the spatial distribution of RVF vectors in Baringo County. Data on species occurrence were obtained from longitudinal sampling of adult mosquitoes and larvae in the study area. We used present (2000) and future (2050) Bioclim climate databases to model the vector distribution.
RESULTS:

Model results predicted potential suitable areas with high success rates for Culex quinquefasciatus, Culex univitattus, Mansonia africana, and Mansonia uniformis. Under the present climatic conditions, the lowlands were found to be highly suitable for all the species. Future climatic conditions indicate an increase in the spatial distribution of Cx. quinquefasciatus and M. africana. Model performance was statistically significant.
CONCLUSION:

Soil types, precipitation in the driest quarter, precipitation seasonality, and isothermality showed the highest predictive potential for the four species.

Olago, D, WoldeGabriel G, Dindi E, Owor M.  2016.  Genesis of the East African Rift System. Soda Lakes of East Africa. : Springer, Cham Abstract

The East African Rift System (EARS) started in Late Oligocene to Early Miocene time and gradually propagated southwards from the Afar Depression, beginning in the Middle Miocene. The hot, low-density mantle material of the Afar Plume heated the overlying lithosphere, causing thinning, regional doming, and the earliest basaltic volcanism in southern Ethiopia. In Ethiopia, the Afar Depression, the Main Ethiopian Rift, and the broadly rifted zone of southwestern Ethiopia represent the northern segment of the EARS.

In the Kenyan sector of the EARS, uplift and doming also gave rise to the Kenya Dome. The radial flow patterns of the initial phonolites provide evidence for doming. Another important observation is that the rift geometry was greatly influenced by pre-existing structures of the underlying Mozambique Mobile Belt. Rifting proceeded through alternating episodes of volcanism and tectonics. Crossing into Tanzania, the influence of the neighbouring Tanzania Craton becomes evident. Here, the rift is expressed only in the northern part, splaying out in diverging half-graben valleys that are outside the Kenya Dome.

Large boundary faults and opposing flexural margins, producing mobile asymmetrical full and half-graben basins that are individually linked along the rift axis, mark the Western Rift Valley. These basins are frequently occupied by elongate and narrow lakes (largely freshwater) separated by accommodation zones and containing significant hydrocarbon resources especially in the Albertine Graben. Small to large lakes existed in the EARS during the Plio–Pleistocene. Lakes in the Western Rift are large and deep, whereas those in the Kenya, Main Ethiopian, and Afar Rifts are generally small and shallow. Geological records indicate that the lakes sensitively responded to orbital forcing as well as to local, regional, and global climatic, environmental, and tectonic changes, resulting in fluctuating lake sizes and even desiccation.

Olago, D, Cohen A, Campisano C, Arrowsmith R, Asrat A, Deino A, Feibel C.  2016.  The Hominin Sites and Palaeolakes Drilling Project (HSPDP): Collecting palaeolake drill cores from the East African Rift Valley to document the environmental context of human origins. Quaternary International. (404):206-207. Abstract

The influence of climate and environmental history on human evolution is an existential question that continues to
be hotly debated, in part because of the paucity of high resolution records collected in close proximity to the key
fossil and archaeological evidence. To address this issue and transform the scientific debate, the HSPDP was devel-
oped to collect lacustrine sediment drill cores from basins in Kenya and Ethiopia that collectively encompass crit-
ical time intervals and locations for Plio-Quaternary human evolution in East Africa. After a 17 month campaign,
drilling was completed in November, 2014, with over 1750m of core collected from 11 boreholes from five areas
(1930m total drilling length, avg. 91% recovery). The sites, from oldest to youngest, include 1) N. Awash, Ethiopia
(

3.5-2.9Ma core interval); 2) Baringo-Tugen Hills, Kenya (

3.3-2.5Ma); 3) West Turkana, Kenya (

1.9-1.4Ma);
L. Magadi, Kenya (0.8-0Ma) and the Chew Bahir Basin, Ethiopia (

0.5-0Ma). Initial core description (ICD) and
sampling for geochronology, geochemistry and paleoecology studies had been completed by mid2014, with the
two remaining sites (Magadi and Chew Bahir) scheduled for ICD work in early 2015. Whereas the primary scien-
tific targets were the lacustrine deposits from the hominin-bearing basin depocenters, many intervals of paleosols
(representative of low lake stands and probable arid periods) were also encountered in drill cores. Preliminary anal-
yses of drill core sedimentology and geochemistry show both long-term lake level changes and cyclic variability in
lake levels, both of which may be indicative of climatic forcing events of interest to paleoanthropologists. Authors
of this abstract also include the entire HSPDP field team

Olago, D, Cohen A, Campisano C, Arrowsmith R, Asrat A, Behrensmeyer AK.  2016.  The Hominin Sites and Paleolakes Drilling Project: inferring the environmental context of human evolution from eastern African rift lake deposits. Scientific Drilling. 21:1. AbstractWebsite

The role that climate and environmental history may have played in influencing human
evolution has been the focus of considerable interest and controversy among
paleoanthropologists for decades. Prior attempts to understand the environmental history
side of this equation have centered around the study of outcrop sediments and fossils
adjacent to where fossil hominins (ancestors or close relatives of modern humans) are
found, or from the study of deep sea drill cores. However, outcrop sediments are often highly
weathered and thus are unsuitable for some types of paleoclimatic records, and deep sea
core records come from long distances away from the actual fossil and stone tool remains.
The Hominin Sites and Paleolakes Drilling Project (HSPDP) was developed to address
these issues.

2015

Olago, D, van der Lubbe HJL, Sier MJ, Feibel CS, Beck C, Dupont-Nivet G, Vonhof H, Joordens JJ, Cohen A, Prins M.  2015.  Sr isotope stratigraphy and lithogenic grain-size distributions of the Pleistocene Turkana Basin, Kenya.
Ochieng, A, Gachie T, Ondiba IM, Nanyingi M, Olago D, Amimo FA, Oludhe C.  2015.  Ecological niche modelling and spatial distribution of rift valley fever vectors in Baringo County, Kenya. JOOUST. AbstractFull Text Link

The Rift Valley fever (RVF) is a vector-borne zoonotic disease that has an impact on human health and animal productivity. It is caused by the Rift Valley Fever Virus (RVFV) which is primarily transmitted by flood water Aedes mosquitoes. Culex spp and Mansonia spp are secondary vectors which pick up the RVFV from domestic animals and amplify the infection to other domestic animals and humans. This study used ecological niche modelling algorithms to predict the effect of climatic variables on habitat suitability and the spatial distribution of RVF vectors in Baringo County. We ran the Boosted Regression trees and Random Forest algorithms to model the spatial distribution of Culex spp. using species occurrence data and AFRICLIM climate data. The species occurrence data was obtained from longitudinal sampling of mosquito larvae in four strata within the study area between June and December 2014. The AFRICLIM climate data consisting of 21 variables was downloaded from https://webfiles.york.ac.uk/KITE/AfriClim. Preliminary results indicate that rainfall, moisture and temperature ranges are the key factors that affect the spatial distribution of Culex spp in Baringo County. Culex spp. is likely to be found in the riverine zone along Kerio River and in the lowlands around Lakes Baringo, 94 and Bogoria.

Olago, D, Dulo SI, Kanoti MJ.  2015.  Sustaining Urban Groundwater-Fed Water Supplies and Sanitation Systems in Africa. The Royal Society.
Olago, D, Christopher Campisano, Asrat A, Arrowsmith R, Deino A, Feibel C, Hill A, Kingston J, Cohen AS, et al.  2015.  The Hominin Sites and Paleolakes Drilling Project (HSPDP): Understanding the paleoenvironmental and paleoclimatic context of human origins through continental drilling. EGU General Assembly 2015, held 12-17 April, 2015 in Vienna, Austria. id.3134. Abstractegu2015-3134.pdfFull Text Link

The influence of climate and environmental history on human evolution is an existential question that continues to be hotly debated, in part because of the paucity of high resolution records collected in close proximity to the key fossil and archaeological evidence. To address this issue and transform the scientific debate, the HSPDP was developed to collect lacustrine sediment drill cores from basins in Kenya and Ethiopia that collectively encompass critical time intervals and locations for Plio-Quaternary human evolution in East Africa. After a 17 month campaign, drilling was completed in November, 2014, with over 1750m of core collected from 11 boreholes from five areas (1930m total drilling length, avg. 91% recovery). The sites, from oldest to youngest, include 1) N. Awash, Ethiopia (~3.5-2.9Ma core interval); 2) Baringo-Tugen Hills, Kenya (~3.3-2.5Ma); 3) West Turkana, Kenya (~1.9-1.4Ma); L. Magadi, Kenya (0.8-0Ma) and the Chew Bahir Basin, Ethiopia (~0.5-0Ma). Initial core description (ICD) and sampling for geochronology, geochemistry and paleoecology studies had been completed by mid2014, with the two remaining sites (Magadi and Chew Bahir) scheduled for ICD work in early 2015. Whereas the primary scientific targets were the lacustrine deposits from the hominin-bearing basin depocenters, many intervals of paleosols (representative of low lake stands and probable arid periods) were also encountered in drill cores. Preliminary analyses of drill core sedimentology and geochemistry show both long-term lake level changes and cyclic variability in lake levels, both of which may be indicative of climatic forcing events of interest to paleoanthropologists. Authors of this abstract also include the entire HSPDP field team.

Olago, DO.  2015.  Country Diagnostic Report, Kenya. International Water Security Conference.

2014

Campisano, CJ, Cohen A, Asrat A, Feibel C, Kingston J, Lamb H, Olago D, Owen R, Renaut R, Schabitz F.  2014.  The Hominin Sites and Paleolakes Drilling Project (HSPDP) drilling campaigns: the trials and triumphs of trying the unique and new. 2014 GSA Annual Meeting in Vancouver, British Columbia. AbstractFull Text Link

Between the summers of 2013 and 2014, the HSPDP successfully completed 4 of its 5 drilling campaigns. To date, >1,200m of core has been collected with the final site at Chew Bahir, Ethiopia scheduled for the end of 2014. The initial core description and sampling have been completed on all but the Magadi cores. Despite the challenges associated with a large-scale multinational project, we have accomplished our goal of collecting lacustrine dominated cores proximate to key paleoanthropological sites. Challenges included the availability/import of suitable drill rigs and equipment in country, long supply lines in remote areas, challenging lithologies for coring and recovery, and interpretation of geophysical data. At our oldest site, 600m of Pliocene-age core was collected from 3 boreholes at 2 sites in the northern Awash, Ethiopia. This resulted in a composite depth of ~285m with significant overlap between cores and >96% core recovery. Several unexpectedly thick basalts not originally identified in seismic surveys were interbedded with lake sediments. Drilling ceased prior to reaching our original target of 500m when rehydrated clays made advancing impractical and work in progress will determine how much of the 2.9-3.8Ma target interval was recovered. A single 228m borehole with ~95% core recovery was drilled at the Plio-Pleistocene Tugen Hills, Kenya location. Just shy of our 250m target depth, preliminary comparisons with outcrop records suggest that this core may cover a time interval of ~2.5-3.45Ma, longer than our original target of 2.5-3.1Ma. A single 216m borehole with ~93% core recovery was drilled at the early Pleistocene West Turkana, Kenya location. Drilling ceased prior to reaching our original target depth of 350m due to complications likely associated with penetrating a hydrothermal fracture system. Nonetheless, tephrostratigraphic data indicates that the core covers our original target interval of ~1.45-2.0Ma. Recently, 202m of modern to Middle Pleistocene core was collected from 4 boreholes at 2 sites at Lake Magadi, Kenya. Challenging lithologies to core/collect (e.g., trona, chert) resulted in core recovery of 55-60%. Contact with the basement trachyte (~800 ka) at each site occurred at 137m and 197m, respectively, shallower than original estimates from low-resolution geophysical surveys.

Olago, D.  2014.  The Morphology and Genesis of Cold-Phase Diamicts in High Altitude Lake Sediments of Mount Kenya, Kenya. Africa Journal of Physical Sciences. 1(1) AbstractFull Text Link

Lake sediment cores spanning the last interglacial-glacial-present interglacial cycle have been recovered from Sacred Lake and Lake Nkunga on the northeastern flank of Mount Kenya, Kenya. Within these cores are diamicts which occur at the last interglacial-glacial transition (ca.110,000 yr BP) and between 58,000 and 48,000 yr BP. The occurrence of the diamicts (formed by active freeze-thaw processes in the lake catchments) is associated with periglacial and concurrent relatively humid conditions at the altitudes of the lakes. In addition, their temporal occurrence is correlated with abrupt low temperature extremes and/or rapid transition rates to lower temperature regimes at high latitude regions. Close modern corollaries of such sediments have been documented at higher altitude on Mount Kenya, but there is no known documentation of such sediments in the late Quaternary records of the tropical high mountains.

2013

Omuombo, C, Huguet A, Olago D, Williamson D.  2013.  Distribution of Glycerol Diakyl Glycerol Tetraethers in Surface Soil and Crater Lake Sediments from Mount Kenya, East Africa. AGU Fall Meeting Abstracts. AbstractFull Text Link

Glycerol diakyl glycerol tetraethers (GDGTs), a palaeoclimate proxy based on the relative abundance of lipids produced by archaea and bacteria, is gaining wide acceptance for the determination of past temperature and pH conditions. This study looks at the spatial distribution and abundance of GDGTs in soil and sediment samples along an altitudinal transect from 3 crater lakes of Mt. Kenya (Lake Nkunga, Sacred Lake and Lake Rutundu) ranging in elevation from 1700m - 3080m above sea level. GDGTs were extracted with solvents and then analysed using high performance liquid chromatography/atmospheric pressure chemical ionization-mass spectrometry (HPLC/APCI-MS). Mean annual air temperature and pH were estimated based on the relative abundance of the different branched GDGTs, i.e. on the MBT (Methylation index of Branched Tetraethers) and CBT (Cyclization ratio of Branched Tetraethers) indices. Substantial amount of GDGTs were detected in both soil and sediment samples. In addition, branched GDGT distribution was observed to vary with altitude. These results highlight the importance of quantifying the branched GDGTs to understand the environmental parameters controlling the distribution of these lipids. The MBT/CBT proxy is a promising tool to infer palaeotemperatures and characterize the climate events of the past millennia in equatorial east Africa.

Olaka, LA, Musolff A, Mulch A, Olago D, Odada EO.  2013.  Lithological Influences on Occurrence of High-Fluoride Waters in The Central Kenya Rift. AGU Fall Meeting Abstracts. AbstractFull Text Link

Within the East African rift, groundwater recharge results from the complex interplay of geology, land cover, geomorphology, climate and on going volcano-tectonic processes across a broad range of spatial and temporal scales. The interrelationships between these factors create complex patterns of water availability, reliability and quality. The hydrochemical evolution of the waters is further complex due to the different climatic regimes and geothermal processes going on in this area. High fluoridic waters within the rift have been reported by few studies, while dental fluorosis is high among the inhabitants of the rift. The natural sources of fluoride in waters can be from weathering of fluorine bearing minerals in rocks, volcanic or fumarolic activities. Fluoride concentration in water depends on a number of factors including pH, temperature, time of water-rock formation contact and geochemical processes. Knowledge of the sources and dispersion of fluoride in both surface and groundwaters within the central Kenya rift and seasonal variations between wet and dry seasons is still poor. The Central Kenya rift is marked by active tectonics, volcanic activity and fumarolic activity, the rocks are majorly volcanics: rhyolites, tuffs, basalts, phonolites, ashes and agglomerates some are highly fractured. Major NW-SE faults bound the rift escarpment while the rift floor is marked by N-S striking faults We combine petrographic, hydrochemistry and structural information to determine the sources and enrichment pathways of high fluoridic waters within the Naivasha catchment. A total of 120 water samples for both the dry season (January-February2012) and after wet season (June-July 2013) from springs, rivers, lakes, hand dug wells, fumaroles and boreholes within the Naivasha catchment are collected and analysed for fluoride, physicochemical parameters and stable isotopes (δ2 H, δ18 O) in order to determine the origin and evolution of the waters. Additionally, 30 soil and rock samples were also collected and analysed for fluoride, and rock samples were subjected to petrographic investigations and X-ray diffraction. The fluoride levels in surface and groundwater for the dry season range from 0.019 - 50.14 mg/L, on average above the WHO permissible limit. The high fluoride occurs both in the lake and groundwater. Preliminary petrographic studies show considerable fluoride in micas. The study is on-going and plans to present the relative abundances of fluoride in the lithology as the sources and the fluoride enrichment pathways of the groundwater within the Central Kenya rift.

Olago, DO.  2013.  Kenya: A Natural Outlook: Chapter 4. Quaternary Evolution. Elsevier Inc. Chapters. 16
Paron, P, Olago DO, Omuto CT.  2013.  Kenya: A Natural Outlook: Methods and Applications. AbstractKenya: A Natural Outlook: Methods and Applications

Kenya is a thriving country in East Africa: its economy is largely based on the natural environment that frames the tourism sector, mainly through safaris and holidays on the coast. The natural environment also underpins the second largest industry: agriculture. Kenya’s social, technological, and industrial developments are a reference for many neighboring countries. Kenya plays a leading role in Africa and attracts huge amounts of investments. Furthermore, the humanitarian community has made Nairobi its base for international headquarters and regional offices. This makes Kenya a possible model for development and investment in its widest sense. This book aims at updating the holistic view on Kenya’s natural environment and resources. It provides a sound scientific introduction to this country’s physical and socioeconomic setting and its evolution through time and will appeal to a broad audience of students – in Kenya and abroad – as well as those working in the development and humanitarian sectors and to international donors looking for a scientific compendium on Kenya’s environment. Its structure and references allow the reader to deepen his or her knowledge of every theme touched on in the book.

2012

Olago, DO, Opiyo Akech N, Moses M.  2012.  Mineral, Oil and Gas Resources. Developments in Earth Surface process . Abstract

The mineral, oil and gas sectors have not played an important role in the economy of Kenya in the past, but the recent discovery of mineral sands and rare earth elements at the coast and oil in the Lokichar Basin in the northern part of the country are proving to be game changers in the mining, oil and gas sectors. The most important minerals mined in the past have been mainly industrial minerals with soda ash and fluorspar being the most important products. Significant tonnage of gold was mined in western parts of Kenya, but currently only minor exploration and production from the old mine sites is taking place. However, with the increased interest and the government resolve to improve mineral exploration, new mineral finds are possible. Exploration for oil and gas has been taking place in Kenya since the 1950s, but it is only recently that significant oil finds have been reported. The findings have inspired several companies to explore for oil and gas within all the major sedimentary basins in Kenya, namely, the Lokichar Basin, Turkana Basin, the Kerio and Baringo Basin, the Anza Basin, and the Lamu Basin.

2010

Junginger, A, Olago DO, Trauth MH.  2010.  The palaeo-lake Suguta and its importance for understanding lake level fluctuations in the East African Rift System. AbstractThe palaeo-lake Suguta and its importance for understanding lake level fluctuations in the East African Rift System

We studied the most recent dry-wet-dry cycle in the presently arid Suguta Valley in the Northern Kenya Rift where a 300-m-deep lake has formed during the so-called African Humid Period (AHP, 14.8-5.5 ka BP). Hydromodeling suggests that a relatively moderate 25% increase in precipitation was responsible for this dramatic lake level rise, which demonstrates the character of the Suguta Valley as an amplifier lake system. To detect the response of this lake system to climate fluctuations and their possible driving mechanisms with a focus on abrupt vs. gradual changes, we reconstructed a palaeo-lake level record for the time between 14 and 5 ka BP from up to 40 m thick lake-sediment sequences at three locations in the ~2,500 km2 palaeo-lake Suguta area. The sediments have been investigated for sediment characteristics such as grain size distributions, detrital and authigenic mineral phases, geochemical properties and microfossil assemblages. The stratigraphy for the sequences is based on 38 AMS 14C ages of biogenic carbonate and charcoal samples. Parallel dating of charcoal and snail-shell samples show age differences between 1,570-2,240 years suggesting a remarkably high, but well-defined reservoir age for palaeo-Lake Suguta most likely due to aged groundwater or 14C depleted CO2 degassing from active volcanoes. The observed reservoir effect highlights the potential problems while correlating East African lake level records with chronologies based on 14C datings of aquatic materials. The new chronology of water level fluctuations in the amplifier-lake Suguta indicates a general dry-wet-dry cycle synchronous with other lake chronologies during the AHP and multiple short-term fluctuations with abrupt lake level drops between 100 to 300 m within 100 to 200 years at 12.8-11.6 (during Younger Dryas time), 11.1-10.9; 10.4-10.2; 9.5-9.1; 9.0-8.8; 8.5-8.1 (during the 8.2 ka event) cal ka BP that seem to be linked with changes in the coupling between atmosphere and ocean systems. In contrast, the termination of the overall lake episode during the AHP shows a relatively gradual (linear) response to the reduction of solar heating due to insolation changes. The results of the analysis provides new insights into the sensitivity of Rift Valley lakes to climate change on different time scales. Abrupt climate shifts most likely caused dramatic environmental pressure on the biosphere, including humans that were already able to adopt relatively quickly to environmnetal change by new technologies during this time.

OCHIENG, DROLAGODANIEL.  2010.  Ochola, S.O., Eitel, B. and Olago, D.O. Vulnerability of schools to floods in Nyando River catchment, Kenya. The Journal of Disaster Studies, Policy and Management. doi:10.1111/j.0361-3666.2010.01167.x. Journal of Climatic Change. : The Journal of Disaster Studies, Policy and Management. doi:10.1111/j.0361-3666.2010.01167.x Abstract
Separation of midgut membrane proteins from the tick, Ambylomma variegatum, using a nonionic detergent (Triton X-114), resulted in two protein fractions, namely DET (detergent) and AQ (aqueous). In immunoblotting analysis with polyclonal antibodies against these fractions, 4 proteins (Mr approximately 27,000, 67,000, 86,000 and 95,000,) and 2 proteins (M, approximately 54,000 and 67,000) were detected in the DET and AQ fractions, respectively. Three of the DET fraction proteins Mr approximately 27,000, 67,000 and 95,000 were glycosylated since they bound to the lectin, concanavalin A. In 2-dimensional gel electrophoresis, the AQ and DET fraction proteins were found to be acidic in nature. In a series of bioassay experiments, rabbits were first immunised with both DET and AQ fractions and then infested with ticks. The egg batch weights of these ticks were reduced by 50% compared to control ticks. Furthermore, there was a significant reduction in the hatchability of eggs laid by ticks fed on rabbits previously immunised with both DET (14%) and AQ (33%) fractions. Based on the egg hatchability, the reproductive capacity of ticks was reduced by 77 and 48% by DET and AQ fractions, respectively.

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