Lake Naivasha Basin Research Articles

Cross-cutting Ties and Coexistence: Intermarriage, Land Rentals and Changing Land Use Patterns among Maasai and Kikuyu of Maiella and Enoosupukia, Lake Naivasha Basin, Kenya

This paper explores the value of cross-cutting ties and conflicting loyalties for the peaceful management of conflicts and the emergence of collective action across previously violently contested community boundaries in two communities in the Lake Naivasha Basin, Kenya. In the researched communities cross-cutting ties result from intermarriages, land rentals and friendship. Fieldwork was conducted in six neighbouring villages on the border between Nakuru and Narok Counties in 2013 and early 2014. Half of these villages fall within the Maiella Sub-location and the other half within Enoosupukia Location. Enoosupukia, especially, has become notorious in the history of ethnicised violence in Kenya’s Rift Valley. In October 1993 more than 20 farmers of Kikuyu descent were killed in an organised assault perpetrated by hundreds of Maasai vigilantes with the assistance of game wardens and administration police; later thousands of farmers were evicted from the area at the instigation of leading local politicians. Nowadays, intercommunity relations between Maasai and Kikuyu are surprisingly peaceful and the cooperative use of natural resources is the rule rather than the exception. How did formerly violent conflicts develop into peaceful relations? How did competition turn into cooperation facilitating changing land use? In this paper we explore the role of cross-cutting ties and the conflicting loyalties associated with them to explain changing community relations.

Firms’ willingness to invest in a water fund to improve water-related ecosystem services in the Lake Naivasha basin, Kenya

A valuation scenario was designed using a contingent-valuation approach and presented to decision makers in business firms in Kenya’s Lake Naivasha basin to test how applicable a water fund might be as a potential financing mechanism for a payment for water-related ecosystem services scheme. The findings indicate that measuring a firm’s willingness to invest in ecosystem services could help determine whether a firm would invest and engage with other stakeholders to pool their investments in ecosystem services. Linking the institutional decision-making behaviour of a firm and its willingness to invest in a water fund is the novelty of this article.

Faecal pollution and solar purification of community water sources within Lake Naivasha basin, Kenya

As in other parts of Africa, and in other developing nations, the rise in the human population and anthropogenic activities within the Lake Naivasha basin is causing an increase in human health risks due to faecal contamination of domestic water sources. This study investigated faecal pollution of community water sources within the Lake Naivasha basin by measuring the densities of total coliforms, Escherichia coli, intestinal enterococci, Clostridium perfringens and heterotrophic bacteria in Lake Naivasha, the Malewa and Gilgil Rivers, and boreholes using membrane filtration techniques and heterotrophic plate count procedures. Selected physico-chemical parameters were also measured in situ from all the water sources sampled. Lakes and rivers had significantly higher microbial abundances than boreholes. Unlike boreholes, surface sources (rivers and lake) showed significant variation with respect to sampling sites for all the microbiological parameters (P < 0.05). The use of solar radiation in water disinfection with temperatures of 75 °C after 30 minutes from pasteurization point (time zero) fully eradicated E. coli and total coliforms from all the water sources. In conclusion, there is faecal pollution in water sources used by communities within the Lake Naivasha basin. The use of solar radiation is therefore recommended for water purification to reduce likely incidences of waterborne diseases.

Characterisation of hydroclimatological trends and variability in the Lake Naivasha basin, Kenya

AbstractRecent hydro‐climatological trends and variability characteristics were investigated for the Lake Naivasha basin with the aim of understanding the changes in water balance components and their evolution over the past 50 years. Using a Bayesian change point analysis and modified Mann–Kendall tests, time series of annual mean, maximum, minimum, and seasonal precipitation and flow, as well as annual mean lake volumes, were analysed for the period 1960–2010 to uncover possible abrupt shifts and gradual trends. Double cumulative curve analysis was used to investigate the changes in hydrological response attributable to either human influence or climatic variability. The results indicate a significant decline in lake volumes at a mean rate of 9.35 × 106 m3 year−1. Most of the river gauging stations showed no evidence of trends in the annual mean and maximum flows as well as seasonal flows. Annual minimum flows, however, showed abrupt shifts and significant (upward/downward) trends at the main outlet stations. Precipitation in the basin showed no evidence of abrupt shifts, but a few stations showed gradual decline. The observed changes in precipitation could not explain the decline in both minimum flows and lake volumes. The findings show no evidence of any impact of climate change for the Lake Naivasha basin over the past 50 years. This implies that other factors, such as changes in land cover and infrastructure development, have been responsible for the observed changes in streamflow and lake volumes. Copyright © 2015 John Wiley & Sons, Ltd.

Detection of trends in extreme streamflow due to climate variability in the Lake Naivasha basin, Kenya

ABSTRACTVariability of streamflow has far-reaching impacts especially in developing countries. This is aggravated by climate change which has adversely affected the water resources and food security. This paper presents the characterization trends in extreme streamflow regimes with a view to providing information for planning local coping mechanisms to climate variability and change using streamflow data recorded from 1959 to 2008 in the Lake Naivasha basin in Kenya. The maxima and percentiles of streamflow distributions were investigated to identify changes in extreme intensity and frequency, respectively, using the Mann–Kendall test. The results indicate significant increases in annual maxima at all gauging stations. The flows in the month of November increased significantly at gauging stations 2GB4 and 2GC4. Flow percentile exceedance revealed that the annual 95th percentile exceedance increased significantly at gauging stations 2GB1 and 2GB5 with a decrease in annual 90th and 97th percentile exceedance at gauging stations 2GB4 and 2GC4. The results presented in this paper are useful for climate change adaptation planning and management especially in water supply, hydropower generation and agriculture.

Simulating the viability of water institutions under volatile rainfall conditions – The case of the Lake Naivasha Basin

This study views the Lake Naivasha Basin in Kenya's Rift Valley as a hydro-economic system with slowly emerging basin-wide water management institutions. Possible institutions face two interlinked challenges. Firstly, large scale horticultural activities as a core economic activity in the basin require substantial and regular amounts of irrigation water, abstracted from the lake and its aquifer. The lake level and thus irrigation water availability reveal a falling trend over the last two decades, which calls for institutions aimed at restricting further expansion in water use. Secondly, the region is characterized by volatile weather conditions where periods of average and above average rainfall have alternated with prolonged droughts for centuries. That leads to highly volatile water inflows into the lake. The two challenges combined thus call for water management institutions that support sustainable water use in both the short and the long run. This study therefore investigates the effect of water institutions already existing or proposed by local stakeholder organizations on preserving target lake levels against a background of highly volatile water availability which negatively affects the economic viability of institutions. To take the absence of functioning basin-wide coordination mechanisms for water allocation into account, we employ the solution format of Multiple Optimization Problems with Equilibrium Constraints (MOPEC) in our integrated hydro-economic model. Stochastic scenario simulations with the model reveal that compliance to water regulations and thus the viability of water institutions in the Naivasha Basin would require very high penalties which are not likely to be accepted by users.

Supporting IWRM through spatial integrated assessment in the Lake Naivasha basin, Kenya

This study describes the mismatch between required knowledge and efforts by scientists and stakeholders in the Lake Naivasha basin, Kenya. In the basin, integrated water resources management (IWRM) suffers from the absence of critically relevant knowledge. This study further presents a spatial integrated assessment framework for supporting IWRM in the basin. This framework resulted from an ongoing debate between stakeholders and scientists studying the basin's issues. It builds on jointly identified indicators for sustainable governance, and their interdependency, and knowledge gaps. For IWRM in the basin this is a first important step towards a more structured debate on the implementation of IWRM.

Estimating the joint effect of multiple soil conservation practices: A case study of smallholder farmers in the Lake Naivasha basin, Kenya

The current study seeks to assess the private benefits associated with multiple soil conservation practices (MSCPs) by estimating the marginal value of crop production that can be attributed to such practices. In areas where land degradation associated with soil erosion causes serious agri-environmental challenges such as loss of soil fertility, siltation and eutrophication, a multiple approach to soil conservation is neccessary. However, notwithstanding efforts to encourage adoption of such practices, their uptake remains generally low. Analysing the effect of MSCPs on crop productivity is one of the ways through which the incentives for soil conservation can be explored. To achieve the stated objective, the current study applied propensity score matching and exogenous switching regression techniques to cross-sectional data collected from a random sample of farm households located in Lake Naivasha basin, Kenya. Results indicate that there is a significant positive effect of implementing multiple soil conservation practices on crop productivity. However, we note that whether the additional benefits will cover the opportunity costs associated with the implementation of these practices will depend on farm specific attributes such as slope and the soil conservation effort. In cases where marginal benefits are not substantial to cover opportunity costs for implementation of soil conservation practices, intrinsic or external incentives could be necessary. Policy interventions could focus on offering technical assistance to farmers in selecting soil conservation practices that are best suited to their local condition.

Coupling socio-economic factors and eco-hydrological processes using a cascade-modeling approach

Most hydrological studies do not account for the socio-economic influences on eco-hydrological processes. However, socio-economic developments often change the water balance substantially and are highly relevant in understanding changes in hydrological responses. In this study a multi-disciplinary approach was used to study the cascading impacts of socio-economic drivers of land use and land cover (LULC) changes on the eco-hydrological regime of the Lake Naivasha Basin. The basin has recently experienced substantial LULC changes exacerbated by socio-economic drivers. The simplified cascade models provided insights for an improved understanding of the socio-ecohydrological system. Results show that the upstream population has transformed LULC such that runoff during the period 1986–2010 was 32% higher than during the period 1961–1985. Cut-flower export volumes and downstream population growth explain 71% of the water abstracted from Lake Naivasha. The influence of upstream population on LULC and upstream hydrological processes explained 59% and 30% of the variance in lake storage volumes and sediment yield respectively. The downstream LULC changes had significant impact on large wild herbivore mammal species on the fringe zone of the lake. This study shows that, in cases where observed socio-economic developments are substantial, the use of a cascade-modeling approach, that couple socio-economic factors to eco-hydrological processes, can greatly improve our understanding of the eco-hydrological processes of a catchment.

Farm households' preferences for collective and individual actions to improve water-related ecosystem services: The Lake Naivasha basin, Kenya

Interventions in payment for ecosystem services (PES) programs can involve both collective and individual actions. This study explores the potential for the development of payment for water related ecosystem services (PWES) program in the Lake Naivasha basin, Kenya. Using a choice experiment approach, the willingness to accept compensation is estimated for three water-related ecosystem services (WES) attributes: one collective attribute (reforestation) and two individual attributes (environment-friendly agricultural practices and restoration of riparian land). Moreover, the preferences of upstream farm households are analysed with regard to sub-basins where a PWES program has already been implemented and sub-basins where it has not been implemented so far. For sub-basins where PWES has already been implemented, environment-friendly agricultural practices is the only significant attribute for local farmers' choice to improve WES. Reforestation and environment friendly agricultural practices are significant attributes for sub-basins where PWES has not been implemented so far. Farm households are willing to accept compensation but there appears to be heterogeneity in preferences for WES attributes. We find differences in farm households' preferences and values for collective and individual actions. Therefore, contrary to the current norm in PES interventions with a uniform compensation scheme, we recommend conservation payments to vary among ecosystem service providers.

Are Small-Scale Irrigators Water Use Efficient? Evidence from Lake Naivasha Basin, Kenya

With increasing water scarcity and competing uses and users, water use efficiency is becoming increasingly important in many parts of developing countries. The lake Naivasha basin has an array of different water users and uses ranging from large scale export market agriculture, urban domestic water users to small holder farmers. The small scale farmers are located in the upper catchment areas and form the bulk of the users in terms of area and population. This study used farm household data to explore the overall technical efficiency, irrigation water use efficiency and establish the factors influencing water use efficiency among small scale farmers in the Lake Naivasha basin in Kenya. Data envelopment analysis, general algebraic and modeling system, and Tobit regression methods were used in analyzing cross sectional data from a sample of 201 small scale irrigation farmers in the lake Naivasha basin. The results showed that on average, the farmers achieved only 63% technical efficiency and 31% water use efficiency. This revealed that substantial inefficiencies occurred in farming operations among the sampled farmers. To improve water use efficiency, the study recommends that more emphasis be put on orienting farmers toward appropriate choice of irrigation technologies, appropriate choice of crop combinations in their farms, and the attainment of desirable levels of farm fragmentation.

Social influence and collective action effects on farm level soil conservation effort in rural Kenya

This paper analyzes the effects of social influence and participation in collective action initiatives on soil conservation effort among smallholder farmers in Lake Naivasha basin, Kenya. We apply binary and ordered probit models in a two stage regression procedure to cross-sectional data collected through a household survey among randomly selected smallholder farmers. Smallholder farming systems in the research area are associated with practices that render farmlands susceptible to soil erosion causing negative impacts on land and the environment. Therefore, strategies that encourage soil conservation are likely to also offer solutions for dealing with agri-environmental challenges and poverty alleviation. Results indicate that social capital facilitates participation in collective action initiatives which then influence individual soil conservation efforts. Neighborhood social influences, subjective norms, gender, education level, farm size, access to credit and livestock ownership also emerge as key determinants of soil conservation effort. Policy implications drawn by this study encourage strategies to increase participation and effectiveness in collective action initiatives as a boost to soil conservation. Implementation of soil conservation practices could also be encouraged through awareness increasing instruments, facilitating access to agricultural micro-credit and paying attention to gender related challenges on knowledge access and rights over land and other natural resources.

Mitigating the Water Footprint of Export Cut Flowers from the Lake Naivasha Basin, Kenya

Kenya’s cut-flower industry has been praised as an economic success as it contributed an annual average of US$ 141 million foreign exchange (7 % of Kenyan export value) over the period 1996–2005 and about US$ 352 million in 2005 alone. The industry also provides employment, income and infrastructure such as schools and hospitals for a large population around Lake Naivasha. On the other hand, the commercial farms have been blamed for causing a drop in the lake level, polluting the lake and for possibly affecting the lake’s biodiversity. The objective of this study is to quantify the water footprint within the Lake Naivasha Basin related to cut flowers and analyse the possibility to mitigate this footprint by involving cut-flower traders, retailers and consumers overseas. The water footprint of one rose flower is estimated to be 7–13 litres. The total virtual water export related to export of cut flowers from the Lake Naivasha Basin was 16 Mm3/yr during the period 1996–2005 (22 % green water; 45 % blue water; 33 % grey water). Our findings show that, although the decline in the lake level can be attributed mainly to the commercial farms around the lake, both the commercial farms and the smallholder farms in the upper catchment are responsible for the lake pollution due to nutrient load. The observed decline in the lake level and deterioration of the lake’s biodiversity calls for sustainable management of the basin through pricing water at its full cost and other regulatory measures. Pricing water at full marginal cost is important, but the conditions in Kenya are unlikely to result in serious steps to full-cost pricing, since many farmers resist even modest water price increases and government is lacking means of enforcement. We propose an alternative in this study that can be implemented with a focus on sustainable water use in flower farming around Lake Naivasha alone. The proposal involves a water-sustainability agreement between major agents along the cut-flower supply chain and includes a premium to the final product at the retailer end of the supply chain. Such a ‘water sustainability premium’ will raise awareness among flower consumers and—when channelled back to the farmers—facilitate the flower farms to install the necessary equipment and implement the right measures to use water in a sustainable manner. The collected premiums will generate a fund that can be used for financing measures to reduce the water footprint and to improve watershed management.

Use of Remote Sensing Data in Evaluating the Extent of Anthropogenic Activities and their Impact on Lake Naivasha, Kenya

This study investigated the anthropogenic activities in Lake Naivasha Basin and how they are influencing the quality of water resources. The poor quality of water in the lake is seen from the presence of water hyacinth (Eichhornia crassipes) and is a reflection of nutrient rich waters. The water hyacinth in Lake Naivasha is associated with major negative economic and ecological impacts. The intensity of land use within the basin was mapped from multispectral Landsat satellite imagery of 1986 (TM) and 2000 (ETM) and SPOT imagery 10 m (resolution) of 2007. From interpreted data, the surface area of the Main Lake has decreased from 134.9 kmin 1986 to 117.5 kmin 2007 (12.9%); that of papyrus and wetland grasslands along the lake shore decreased from 54.6 kmto 34.3 km� (37.2%) and that of the horticultural and irrigated farms increased by 103.3% from 45.1 kmto 91.7 kmin the same period, placing great pressure on both the quality and quantity of the lake's water resources. Information obtained from the Fisheries Department in Lake Naivasha show that the fishery production declined from 513 to 110 tons in the period considered. The Naivasha Municipal Council records indicate a 30% decline in the water it supplies to Naivasha Town from 10,000 m 3 to 7,000 m 3 in the same period despite the increase in population. The decline was attributed to many factors among them the presence of water hyacinth and the decline in water quantity due to increased human activities.

Dispatches

Dispatches

Evaluation of the temporal variability of the evaporative fraction in a tropical watershed

Evaporation exhibits diurnal variation in response to the changes in the available energy at the land surface. This requires continuous measurements of evaporation to determine daily total evaporation. This is not feasible without sophisticated field equipment, which at the end, only provides field scale evaporation rates. Remote sensing methods are a good alternative but these give snapshot measurements. If the partitioning of available energy into the different surface fluxes can be assumed to be diurnally constant, then instantaneous remotely sensed measurements could be used to derive daily total evaporation. In situ evaporation measurements were obtained for about a year at a grassland and woodland site in the Lake Naivasha basin, Kenya. These measurements were used to test the validity of the diurnal constancy of the partitioning of the available energy, expressed as evaporative fraction, and the extrapolation of evaporation from instantaneous to daily totals. A good relationship between midday and average day evaporative fraction was obtained at the two sites. Estimated daily evaporation from midday evaporative fraction was within 10% of measured evaporation for both sites. The deviation reduced if evaporation is further integrated in time. The seasonal progression of evaporative fraction is gradual at both sites although grassland evaporative fraction responds faster to changes in rainfall and moisture availability. The results provide a basis for the determination of regional evaporation across a season in tropical watersheds if evaporative fraction is determined instantaneously at intermittent intervals of 5–10 days.

Paleoprecipitation estimates for the Lake Naivasha basin (Kenya) during the last 175 k.y. using a lake-balance model

We modeled the two most extreme highstands of Lake Naivasha during the last 175 k.y. to estimate potential precipitation/evaporation changes in this basin. In a first step, the bathymetry of the paleolakes at ∼135 and 9 k.y. BP was reconstructed from sediment cores and surface outcrops. Second, we modeled the paleohydrologic budget during the highstands using a simplified coupled energy mass-balance model. Our results show that the hydrologic and hence the climate conditions at ∼135 and 9 k.y. BP were similar, but significantly different from today. The main difference is a ∼15% higher value in precipitation compared to the present. An adaptation and migration of vegetation in the cause of climate changes would result in a ∼30% increase in precipitation. The most likely cause for such a wetter climate at ∼135 and 9 k.y. BP is a more intense intertropical convergence and increased precipitation in East Africa.

A new simple method to determine crop coefficients for water allocation planning from satellites: Results from Kenya

Crop coefficient Kc is defined as theratio of crop potential and grass referenceevapotranspiration. This paper discussesthe estimation of crop potentialevapotranspiration from remote sensing datato deduce spatial variable and regionalscale crop coefficients. Maps of cropcoefficients avoid the need to frequentlyuse remote sensing data because grassreference evapotranspiration obtained fromroutine weather data describe the shorterterm day-to-day variation. The new methodis based on the simplified Priestley &Taylor equation for cropevapotranspiration. It is argued that thisis justified for humid conditions and thecalculation procedure is validated withfield data collected from irrigatedvegetables in Kenya. The method isthereafter applied to Landsat-TM satellitedata covering the Lake Naivasha Basin,Kenya, and the spatially variable cropcoefficients are determined. This simpletechnique improves the planning ofirrigation water resources because Kcestimations based on satellite imagesreveal the real agricultural practicesbetter than expected acreage data andtabulated Kc-values published in theinternational literature.

Late Quaternary Shorelines of Lake Naivasha, Kenya

Summary Dr. Celia Kamau is on the staff of Kenyatta University College, Nairobi. She has carried out exhaustive research on the lake basins of the central Rift Valley, much of it in association with archaeologists. The Lake Naivasha basin in the Kenya Rift Valley contains evidence that the lake has formerly stood well above its 1972 level of about 1890 m. This evidence was located and levelling was undertaken to determine the elevation of the former high lake shoreline or shorelines. A possible beach ridge was located at an elevation of 2006–2008 m, and beach gravels of obsidian, lava and pumice occurred at many localities up to a maximum of 1990–1996 m. It may tentatively be concluded that the lake rose to a maximum level of 2000±10 m. No conclusive proof of a lower shoreline level could be found. At present a rising lake in this basin would flow southwards down the Njorowa Gorge when it reached an elevation of 1940–1950 m: lowering of the terrain in this area has clearly taken place since the time of th...