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

2019

Kanoti, JR, Olago D, Opiyo N, Nyamai C, Dindi E, Kuria Z.  2019.  Characterization of Major Ion Chemistry and Hydro-Geochemical Processes in Mt. Elgon Trans-Boundary Aquifer and Their Impacts on Public Health. Journal of Environment and Earth Science. 9(4):38-45. Abstract47529-51080-1-pb.pdfWebsite

There is a gradual paradox shift from the utilization of surface water to groundwater in both urban and rural Kenya. This is because surface water is both diminishing in quantity due to climate variability and deteriorating in quality due to high levels of anthropogenic contamination. In the quest to attain the Sustainable Development Goal number 6 that aim at ensuring access to safe water by all by 2030, the Government of Kenya is encouraging the development of groundwater resources whose potential is enormous though it has not been quantified. The Inter-governmental Authority on Development (IGAD) supported this research on the shared Mt. Elgon trans-boundary aquifer between Kenya and Uganda aimed at understanding its dynamics. Mt. Elgon is a Tertiary age mountain that straddles the Kenya-Uganda border and has a trans-boundary aquifer. This study investigated the groundwater chemistry and its implication on water management and human health. Physico-chemical parameters of water that included electrical conductivity, pH, and temperature were measured in the field and the major cations and anions were measured at the Central Laboratories of the State Department for Water. Geological mapping and identification of sanitary risks were undertaken during the field work. The study revealed that the concentration of cations and anions in the groundwater varied spatially and temporally. Abundance of these ions were in the order Ca²⁺ > Na⁺ > Mg²⁺ > K⁺ for most samples and HCO₃⁻ > Cl⁻ > SO₄²⁻ >NO₃⁻. Interpretation of hydro-chemical data suggests that calcium carbonate dissolution, halite dissolution, Ca/Na ion exchange and Mg/Na ion exchange are the major processes that control the ground-water chemistry. Chemical results indicate further that the groundwater is suitable for domestic use but is threatened by both anthropogenic and geological factors. Extensive use of fertilizer and the destruction of the catchment area coupled with low permeability and rock-water interactions in the metamorphic rock terrains are the main threats to groundwater quality in the region. A few water points had water with some ionic composition exceeding WHO and the local KEBS maximum limits for drinking water. Such water pose a risk to human health.

Xu, Y, Seward P, Gaye C, Lin L, Olago DO.  2019.  Groundwater in Sub-Saharan Africa. Hydrogeology Journal. 27(3):815–822. AbstractWebsite

Sub-Saharan Africa (SSA; Fig. 1) refers to an area encompassing the countries in Africa that are fully, or partially, located south of the Sahara. The remaining African countries are generally referred to as belonging in North Africa. Although the socio-economic and hydrogeological conditions in SSA are diverse, they are sufficiently distinct (in general) from the conditions in North Africa to warrant being assessed separately—for example, high-yielding, high-storage, sedimentary aquifers are more common in North Africa than in SSA, while low-yielding, low-storage, basement aquifers are more widespread in SSA than in North Africa. The use of fossil groundwater is more typical in North Africa, while the use or renewable groundwater is more typical in SSA. Other hydrological characteristics associated with SSA include: groundwater resources that are generally under-utilized; lack of research and development that often prevents the optimal use of groundwater rather than over-development; and a heavy reliance by the rural and urban poor on shallow unconfined or semi-confined groundwater for potable water supplies, other domestic uses, and subsistence agriculture. Because of distinguishing characteristics such as these, there are good reasons for treating the hydrogeology of SSA as a whole, and separate from North Africa.

KANOTI, JR, Olago D, Opiyo N, Nyamai C, Dulo S, Ayah R.  2019.  Microbial and Physical Chemical Indicators of Groundwater Contamination in Kenya: A Case Study of Kisumu Aquifer System, Kenya. Journal of Water Resource & Protection. 11:404-418. Abstractjwarp_2019042514420797.pdfWebsite

Safe water of adequate quantity, and dignified sanitation, is vital for the sustenance of a healthy and productive human population. In the recognition of this, the United Nations formulated the Sustainable Development Goal No. 6 to ensure access to safe water and sanitation by all by 2030. Actualization of this Goal requires information on the existing status of water resources and sanitation levels. Knowledge on contamination of groundwater is essential to prevent risks to human health. The objective of this study was to determine groundwater contamination in Kisumu, Kenya. A total of 275 water samples were collected from 22 sites within the informal settlements between December 2016 and December 2017. The samples were analysed for bacterial contamination and physical chemical quality. Thermal tolerant coliform bacteria enumeration was used as a proxy to bacteria contamination, and the pH, turbidity, dissolved oxygen, conductivity, salinity and temperature were used as physical chemical indicators of contamination. The results indicate that groundwater in Kisumu hosed coliform bacteria and therefore didn’t comply with contamination limits for domestic water proposed by WHO and local KEBS standards. The results further indicated that the levels of bacteriological contamination vary with water type, shallow well having the highest bacterial loads. The study concluded that there were potential risks to human health due to high content of coliform bacteria. The study attributed the contribution to pit latrines that were present in virtually all compounds. The pit latrines are located close to the water points. The study recommended the definition of minimum distance between the pit latrines and shallow wells to minimize contamination. The low income dwellers should be educated on simple ways of treating drinking water contaminated by microbial to minimize enteric infections.

Mnyika, GM, Olago DO.  2019.  The Potential for CO2 Geosequestration in Kenya: A Suitability Assessment of the Lamu Basin. Africa Journal of Physical Sciences. 3:28-38. Abstract1798-6305-1-pb.pdfWebsite

There is a consensus that current trends in climate change may be due to increasing concentrations of greenhouse gases (predominantly methane and carbon dioxide) from anthropogenic emissions. Among measures proposed for curbing this increase is Carbon Capture and Sequestration (CCS) in geological media. CCS incorporates three technologies comprising; (a) carbon capture, (b) compression and transportation, and (c) injection into geological media. This paper focuses on CO2 injection into geological media and its applicability to the Lamu basin. Sedimentary basins, which host the geological formations suitable for subsurface CO2 storage, are ideal to varied extents determined by such factors as their tectonic settings. A (coarse) basin scale suitability assessment of the Lamu basin was undertaken using the following parameters; size and depth, tectonic and structural settings, seismicity, geothermal-hydrodynamic regimes, basin maturity (based on hydrocarbon well density) and economic resources. The assessed attributes are used to constrain GIS data, delineating possible CCS trap areas with the production of a preliminary map of potential trap areas. Also, a suitability matrix table is generated in comparison with analogous basins such as the Alberta basin in Canada. Following this assessment, the Lamu basin can be considered geologically suitable for geosequestration given its stable tectonic settings, good depth and size. However, the western flanks of the basin and the coastal strip are unsuitable due to shallowness, population and protected zones respectively.

Ferrer, N, Folch A, Lane M, Olago D, Odida J, Custodio E.  2019.  Groundwater hydrodynamics of an Eastern Africa coastal aquifer during the recent La Niña 2016-17 drought. Science of The Total Environment. 661:575-597. AbstractWebsite

In 2016–17 much of East Africa was affected by a severe drought which has been attributed to Indian Ocean Dipole and El Niño Southern Oscillation conditions. Extreme events such as this have immediate and knock-on effects on water availability for household, agricultural and industrial use. Groundwater resources can provide a buffer in times of drought, but may themselves be stressed by reduced recharge and increased usage, posing significant challenges to groundwater resource management. In the context of East Africa, groundwater management is also hampered by a lack of information on aquifer characteristics. With the aim of addressing this knowledge gap, this study shows the hydrogeological behaviour before and during La Niña 2016/17 drought in southern coastal Kenya on a groundwater system which sits within a geological structure which is representative of an important portion of the East African coast. Diverse hydrochemical and isotopic campaigns, as well as groundwater head variation measurements, were carried out to study the groundwater hydrodynamics and thus characterize the aquifer system under climatic conditions before and during the La Niña event. This information is complemented with an estimation of changes in local recharge since 2012 using local data sets. The main consequence of the drought was a 69% reduction of recharge compared to an average climatic year. There was reduced recharge during the first rainy season (April–June) and no recharge during the second wet season (October–December). There was a concurrent increase in seawater intrusion even during the wet season.

Olago, DO.  2019.  Constraints and solutions for groundwater development, supply and governance in urban areas in Kenya. Hydrogeology Journal. 27(3):1031–1050. Abstractolago2019_article_constraintsandsolutionsforgrou.pdfWebsite

Based on a five-town case-study cohort in Kenya, a conceptual framework has been developed to enable the formulation of holistic and effective strategies that encompass the national aspirations and regional to global sustainability agendas, and which can be used to monitor progress in achieving set objectives. The approach is flexible, scalable and transferrable, so that it can be applied in different contexts and using different indicators, based upon the same construct. Insufficient technical knowledge of urban aquifers and their interplay with the wider social-ecological system constrains the development of holistic, effective and robust management systems to ensure their sustainability for intended uses. The objective was to consider governance and management solutions that could promote water security for urban towns in Kenya through the sustainable use of groundwater in the context of its complex hydrogeology, water access disparities, competing uses and future risks. The in force national and county water policies, strategies, and plans for the case study areas were critically reviewed. The status of aquifer knowledge, water access disparities, competing uses, and risks was evaluated from critical literature reviews and data compilation, fieldwork, and analysis of indicator datasets from the Kenya 2009 census. Key aquifers need urgent characterisation to reverse the current situation whereby development proceeds with insufficient aquifer knowledge. Private sector and public participation in management should be enhanced through decentralised management approaches. Water infrastructure and technologies should be fit-for-purpose in application and scale, and the pro-poor focus should be underpinned by appropriately focused management regimes.

2018

Gannon, KE, Conway D, Pardoe J, Ndiyoi M, Batisani N, E. O, Olago D, Opere A, et al.  2018.  Business experience of floods and drought-related water and electricity supply disruption in three cities in sub-Saharan Africa during the 2015/2016 El Niño. Global Sustainability . 1:e14. AbstractWebsite

The El Niño event in 2015/2016 was one of the strongest since at least 1950. Through surveys and interviews with key informants, we found businesses in the capital cities of Zambia, Botswana and Kenya experienced major disruption to their activities from El Niño related hydroelectric load shedding, water supply disruption and flooding, respectively. Yet, during the 2015/2016 El Niño, fluctuations in precipitation were not extreme considering the strength of the El Niño event. Results therefore highlight that even fairly moderate precipitation anomalies can contribute to major disruption to economic activity. Addressing the risk of disruption – and supporting the private sector to adapt – is a development priority.

Muhati, GL, Olago D, Olaka L.  2018.  Past and projected rainfall and temperature trends in a sub-humid Montane Forest in Northern Kenya based on the CMIP5 model ensemble. Global Ecology and Conservation. 16:e00469. Abstract1-s2.0-s2351989418301562-main.pdfWebsite

Abstract

This study presents past and projected temporal changes in mean temperature and rainfall around the Marsabit Forest Reserve (MFR), a sub-humid montane forest in Kenya. Rainfall data for the period 1961–2014 and temperature data for the period 1972–2011 were acquired from the Marsabit meteorological station. Future projections (2006–2100) were based on data from five models that participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) under Representative Concentration Pathways (RCPs) 4.5 and 8.5. Climate simulations for the 2071–2100 period were compared to the 1961–1990 IPCC baseline period to establish significant change. The MFR recorded a mean rainfall of 784 mm which declined annually at a rate of 6 mm over the period of the study. The long rains (March–May) recorded a mean of 379 mm and decreased annually by 10 mm while the short rains (October–December) recorded a mean of 269 mm and decreased annually by 2 mm between 1961 and 2014, with no statistically significant trend (p > 0.05).

The model ensemble reproduced the MFR bimodal rainfall pattern, but overestimated the short rains at 333 mm, compared to the actual mean of 269 mm, and underestimated the long rains at 331 mm, compared to the actual mean of 379 mm. The model ensemble simulated a historical mean rainfall of 651 mm compared to the actual mean of 784 mm. Annual rainfall is projected to increase under both scenarios with higher increases during the OND season compared to the MAM season and under RCP8.5 than under RCP4.5. The mean rainfall in the baseline year was 859 mm while the mean rainfall in the projection period for the RCP4.5 and RCP8.5 scenarios is expected to be 1022 (+19%) and 1105 (+28.7%) mm, respectively; significant enough to be characterized as climate change.

Temperatures are projected to increase at a rate of 0.2 °C and 0.5 °C per decade under RCP4.5 and RCP8.5, respectively. Between 2071 and 2100, the MFR is projected to have warmed by between 1.2–1.7 °C and 3.2–4.8 °C under RCP4.5 and RCP8.5, respectively. Extreme rainfall events are projected to increase under the RCP4.5 scenario (severe wetting 13.1%, severe drying 3%) and the RCP8.5 scenario (severe wetting 20.1%, severe drying 3%) compared to the baseline period (severe wetting 6.1%). Our results conform to the ‘East African climate paradox’, where the observed rainfall trends were declining compared to the scenario simulations projecting a wetting anomaly as local temperatures rise. Further studies to better understand the cause of the poor rainfall simulation in the general circulation models (GCMs) in the MFR and the larger East African region will be necessary.

Hirpa, FA, Dyer E, Hope R, Olago DO, Dadson SJ.  2018.  Finding sustainable water futures in data-sparse regions under climate change: Insights from the Turkwel River basin, Kenya. Journal of Hydrology: Regional Studies. 19:124-135. Abstract1-s2.0-s2214581818302155-main.pdfWebsite

Study region

the Turkwel river basin, Kenya experiences a high level of water scarcity due to its arid climate, high rainfall variability and rapidly growing water demand.
Study focus

Climate change, variability and rapid growth in water demand pose significant challenges to current and future water resources planning and allocation worldwide. In this paper a novel decision-scaling approach was applied to model the response of the Turkwel river basin’s water resources system to growing demand and climate stressors. A climate response surface was constructed by combining a water resource system model, climate data, and a range of water demand scenarios.
New hydrological insights

The results show that climate variability and increased water demand are each important drivers of water scarcity in the basin. Increases in water demand due to expanded irrigation strongly influences on the resilience of the basin’s water resource system to droughts caused by the global climate variability. The climate response surface offers a visual and flexible tool for decision-makers to understand the ways in which the system responds to climate variability and development scenarios. Policy decisions to accelerate water-dependent development and poverty reduction in arid and semi-arid lands that are characterised by rapid demographic, political and economic change in the short- to medium term have to promote low-regrets approaches that incorporate longer-term climate uncertainty.

Wetendea, E, Olago D, Ogarac W.  2018.  Perceptions of climate change variability and adaptation strategies on smallholder dairy farming systems: Insights from Siaya Sub-County of Western Kenya. Environmental Development. 27:14-25. AbstractWebsite

Climate change and variability is bound to impact Smallholder Dairy Farming Systems as a result of overreliance on rainfed fodder production; yet climate models project increased frequencies of droughts that have a bearing on the Length of Growing Period. Similarly higher environmental temperatures are partly attributed to biome-range shifts, implying a likelihood of emerging and re-emergence of livestock and fodder diseases and pests. Nonetheless not much is documented of perceptions and adaptation strategies employed by Smallholder Dairy Farming Systems geared towards resilience to climatie shocks. By employing a mixed method approach that included household surveys, focused group discussions and statistical data analysis using SPSS package, this study aimed to bridge some of the existing gaps in adaptation strategies on Smallholder Dairy Farming Systems in Siaya Sub-County of Western Kenya. Survey results obtained from 100 households and Focused Group Discussions revealed that the climate of the study location was perceived to have changed, with droughts singled out as the most frequent. These perceptions were consistent with long-term climate data analysis which affirmed that all seasons, i.e. MAM, JJA, and DJF with the exception of SON showed longterm drying trends. Similarly, environmental temperature showed upward trends in both maximum and minimum temperatures that were perceived to be the cause of proliferation of noxious weeds previously associated with hotter areas of the Sub-County. Typologies of adaptation strategies used in the study showed that adaptation options were limited since these were viewed through a narrow lens of disease control by regular spraying and maize stovers as supplementary livestock feed during fodder dearth periods. This study recommends that besides awareness creation of adverse impacts of climate change and variability, facilitation for ease of access to technologies that ameliorate its adverse effects ought to be put in place. Additionally, empirical studies on consequences of biome range shifts on pasture and fodder productivity, and future possible impacts of diseases on Bos taurus breeds associated with climate change and variability should be undertaken.

Muriithi, GM, Olago DO, Ouma GO, Oriaso SO.  2018.  Reliability of Indigenous Traditional Knowledge and Conventional Weather Forecasting in the Face of Climate Change and Variability in Baringo County, Kenya. . International Journal of Recent Scientific Research. 9(7):28136-28141. Abstract10674-a-2018.pdfWebsite

The research study evaluated the reliability of Indigenous Traditional Knowledge (ITK) and conventional weather forecasts in the face of climate change and variability in Baringo County, Kenya. Systematic sampling technique was applied in drawing a sample size of 454 pastoralists and agro-pastoralists interviewed. Majority (68%) of the respondents have not been aware of blend/mixture of ITK and scientific forecasting techniques. Majority (78% ,77 %,74%, 61%,73%,73% and 71%) of the respondents perceived that conventional weather forecast approach is reliable on predicting short-rains season, long-rain season, rainfall intensity, landslide, thunder storm, expected rainfall onset and cessation, and El-Nino respectively. The majority (71%, 69%, 75% and 64%) of the pastoralists and agro-pastoralists professed that ITK weather forecast approach is reliable on predicting floods, seasonal rain distribution, temperatures and La-Nina respectively. None of the two weather forecasts approaches could exhaustively forecast the climate/weather events alone. The integration of the two approaches is ultimate for effective reliability.

Kaoga, J, Ouma G, Olago D, Ouma G.  2018.  The shrinking grazing fields of the Maasai land under the changing climate system in Kajiado County, Kenya. International Journal of Economics and Sustainable Development. Abstract137075-327682-1-pb.pdfWebsite

The Maasai pastoralists have in the last decade experienced disruptions in their economies and livelihoods following climate shifts. For instance, they have been losing up to 30 % of their herd annually to drought related disasters, yet information on the various land uses is still fragmented. This has been worsened by the shortening famine cycles which has impacted pastoral livelihood system as they highly depend on natural resource. Yet, these key resources have been dwindling over the past 30 years compromising their ability to meet basic need such as food. To address this gap, the study focused on long term evaluation of land use. The study’s objective was to determine land use transformations and their impacts particularly on the pastoral livelihood system.

Amadi, JA, Olago DO, Ong’amo GO, Oriaso SO, Nanyingi M, Nyamongo IK, Estambale BBA.  2018.  Sensitivity of vegetation to climate variability and its implications for malaria risk in Baringo, Kenya. Abstractjournal.pone_.0199357.pdfWebsite

The global increase in vector borne diseases has been linked to climate change. Seasonal vegetation changes are known to influence disease vector population. However, the relationship is more theoretical than quantitatively defined. There is a growing demand for understanding and prediction of climate sensitive vector borne disease risks especially in regions where meteorological data are lacking. This study aimed at analyzing and quantitatively assessing the seasonal and year-to-year association between climatic factors (rainfall and temperature) and vegetation cover, and its implications for malaria risks in Baringo County, Kenya. Remotely sensed temperature, rainfall, and vegetation data for the period 2004–2015 were used. Poisson regression was used to model the association between malaria cases and climatic and environmental factors for the period 2009–2012, this being the period for which all datasets overlapped. A strong positive relationship was observed between the Normalized Difference Vegetation Index (NDVI) and monthly total precipitation. There was a strong negative relationship between NDVI and minimum temperature. The total monthly rainfall (between 94 -181mm), average monthly minimum temperatures (between 16–21°C) and mean monthly NDVI values lower than 0.35 were significantly associated with malaria incidence rates. Results suggests that a combination of climatic and vegetation greenness thresholds need to be met for malaria incidence to be significantly increased in the county. Planning for malaria control can therefore be enhanced by incorporating these factors in malaria risk mapping.

Kaoga, J, Ouma G, Olago D, Ouma G.  2018.  The Evidence of Changing Rainfall Patterns in Kajiado County, Kenya. International Journal of Innovative Research and Development. 7(6):223-228. Abstract137075-327682-1-pb.pdfWebsite

The Maasai pastoralists have in the past decade experienced disruptions as precipitation season shifts. These shifts have adversely affected their economies and livelihoods. Moreover, they have been losing up to 30 % of their herd annually to drought related disasters, yet the locals’ capacity on climate pattern shifts is inadequate. To address this gap, a study focused on Kajiado County due to its harboring large of livestock. The study aimed at determining the historical precipitation characteristics. To achieve this, the study utilized Climate Hazards group Infra-Red Precipitation with Stations data set (CHIRPS) for the period 1983-2014 for each of the five sub-counties within Kajiado County. The key findings, encompassed: declining trend in the average annual precipitation; shifting from the usual bi-modal rainfall seasons with March to May (MAM) experiencing worst failure compared to October to December (OND) and the shortening of the famine cycles.

JA, A, GO O'amo, DO O, SO O, IK N, BBA E.  2018.  Mapping potential Anopheles gambiae s.l. larval distribution using remotely sensed climatic and environmental variables in Baringo, Kenya.. Medical and Veterinary Entomology. 1(1):417-426. AbstractWebsite

Anopheles gambiae s.l. (Diptera: Culicidae) is responsible for the transmission of the devastating Plasmodium falciparum (Haemosporida: Plasmodiidae) strain of malaria in Africa. This study investigated the relationship between climate and environmental conditions and An. gambiae s.l. larvae abundance and modelled the larval distribution of this species in Baringo County, Kenya. Mosquito larvae were collected using a 350-mL dipper and a pipette once per month from December 2015 to December 2016. A random forest algorithm was used to generate vegetation cover classes. A negative binomial regression was used to model the association between remotely sensed climate (rainfall and temperature) and environmental (vegetation cover, vegetation health, topographic wetness and slope) factors and An. gambiae s.l. for December 2015. Anopheles gambiae s.l. was significantly more frequent in the riverine zone (P < 0.05, r = 0.59) compared with the lowland zone. Rainfall (b = 6.22, P < 0.001), slope (b = - 4.81, P = 0.012) and vegetation health (b = - 5.60, P = 0.038) significantly influenced the distribution of An. gambiae s.l. larvae. High An. gambiae s.l. abundance was associated with cropland and wetland environments. Effective malaria control will require zone-specific interventions such as a focused dry season vector control strategy in the riverine zone.

Muhatia, GL, Olago PD, Olaka DL.  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(1):e00402. Abstract1-s2.0-s2351989418300581-main.pdfWebsite

Abstract

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 2044 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.

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.  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.

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