The floor of the Rift Valley in central Kenya is home to Lake Nakuru National Park, which spans an area of 188 square kilometers.
The coordinates of Lake Nakuru are 0 22 S,36 05 E and its elevation is 1,759 m above sea level. This lake covers an area of 44 sq. km and is part of a chain of endorheic, hypereutrophic, alkaline-saline lakes in the eastern Rift Valley. Despite its challenging environment for aquatic organisms (with pH levels at 10.5 and conductivity ranging from 9,000-160,000 uS, along with intermittent dry periods), there are a few species that thrive and are well-adapted to these conditions. As a result, Lake Nakuru has a significant producer and consumer biomass.
Lake Nakuru is renowned globally for its diverse bird population and particularly for the abundant gatherings of lesser flamingos (Phoeniconaias minor) found there. These particular flamingos make up around 78% of the global flamingo population, with the alkaline lakes in southern Kenya hosting a significant portion of this population, with approximately one-third to one-quarter residing in Lake Nakuru. The lake has been known to attract exceptionally large numbers of lesser flamingos.
In July 1993, the lake was home to 1.5 million birds due to its high primary productivity which attracts this species. Apart from flamingos, there are also 51 other species of water birds found both on the lake and in its littoral fringe.
Within Lake Nakuru National Park, there are various species of Palearctic waders, ducks, and geese, which make it a crucial stopover for Palearctic migrants along the Rift Valley flyway (Finlayson and Pomeroy, 1990). Additionally, the park is home to 350 terrestrial bird species across nine ecological niches, surpassing the number of bird species found in the entire British Isles.
The rich wildlife of Lake Nakuru National Park, including 50 species of mammals such as the endangered Black Rhinoceros and the Rothschild Giraffe, as well as its 500 species of flora, establish it as one of Kenya’s most thrilling habitats.
Lake Nakuru’s Human Occupation and Its Impacts on the Environment
The catchment basin of Lake Nakuru, which covers an area of 1,800 sq. km., is located at its lowest point. The lake’s water balance is sustained by multiple sources including evaporation and precipitation, inflowing rivers, alkaline springs, and groundwater recharge.
During the last century, the catchment basin has experienced substantial transformations. In the past, it was a scarcely inhabited and densely wooded region with abundant wildlife (Percival, 1928). Nonetheless, it has now become densely populated, extensively farmed, and urbanized. The recent settlement history is relatively young since the catchment area became open for settlement in 1889 when the Kenya-Uganda Railway reached it. This increased accessibility led to European farmers migrating to the area.
The area saw the rise of ranches and large mixed farms, resulting in the growth of Nakuru. The town became a district headquarters and the agricultural capital of the Rift Valley, with a population of 14,000 people by 1948. However, these changes had a negative impact on wildlife. Loss of habitat, disruption of migratory routes, and unregulated hunting led to the decline and scattering of various wildlife species (Kutilek, 1974).
By 1960, several species such as Black rhinos, Maasai giraffes, and Elands had been almost eradicated from the area. Additionally, Nakuru hartebeest, in particular, were completely wiped out. The year 1963 marked the independence of the country, leading to a second push for settlement and subsequent modifications in land utilization. In 1967, the government introduced settlement projects that attracted small-scale farmers to the catchment basin. These farmers initially occupied the land that was previously owned by Europeans as large-scale farms.
Due to government initiatives, the creation of land-buying companies, and the illegal occupation by squatters, the number of settlements greatly increased in the following decade. This expansion led to a rapid encroachment into forest reserves. From 1970 to 1986, it is estimated that over 400 sq. km of forest and areas covered in natural vegetation were cleared for cultivation and settlement purposes. Additionally, large holdings that were bought from European owners were divided into smaller parcels of land that are individually owned.
According to the Nakuru District Environmental Report (1987), peasant farmers migrated into the catchment area until the 1980s. However, this movement was halted due to limited available land and insufficient government funding for settlement schemes. As a result, there was an abrupt and unprecedented rise in population density within the catchment area. In one of the earliest settlements, population density increased from 124 persons per sq. km in 1969 to 915 persons per sq. km in 1987 (WOODEC, 1987). Although rural population densities were lower in other parts of the catchment, they still grew from 164 persons per sq. km in 1979 to approximately375 persons per sq. km by1996.
A comparison between catchment maps from 1970 and 1986 reveals significant changes in land use during that period. The percentage of land covered by forests and natural vegetation decreased from47%to only26%of the total catchment area. Moreover, large-scale farms experienced a decrease in their occupied areas; they went down from approximately34%and21%of the catchment area to about13%and11%, respectively.
The area that was once occupied by large commercial farms and wildlife areas has now been replaced by small-scale subsistence farms, which now make up over 35% of the total area. Nakuru Municipality, located less than a kilometer from the northern shore of the lake, has expanded significantly since 1970 when it covered only 8.5 sq. km. Currently, it encompasses an area of 73 sq. km. The population of Nakuru has also experienced substantial growth, increasing from 47,151 individuals in 1969 to 92,880 in 1979. This growth can be attributed to a combination of rural-urban migration, natural population increase, and efforts to promote industrial development. At present, Nakuru’s population is estimated at approximately 360,000 and is growing at a rate of 10% per year.
The described changes in land use have significant consequences for the lake and its distinctive ecology. The extensive clear-cutting of forests may result in the immediate loss of nutrients due to the removal of vegetation alone. Furthermore, the exposure of bare ground and alterations in surface run-off can lead to a continued export of nutrients and soils from the deforested areas for several years. As Lake Nakuru is situated at the lowest point of the catchment, it becomes the ultimate receptor of sediment and nutrient loads transported by feeder rivers.
Strict regulations are now in place to control the removal of forests. Despite these regulations, soil loss still occurs in present-day plantation forests due to activities like road construction and timber extraction. The removal of natural ground cover is believed to have changed the way water is stored and distributed in the area. This loss of soil and alteration of the hydrological regime have led to a decrease in the amount of water available from boreholes and less surface flow into Lake Nakuru (Kimani et al., 1992).
Modern agriculture has resulted in significant consequences such as persistent soil erosion since the 1930s and noticeable environmental contamination due to improper agrochemical use.
As land use intensity increases, the environmental impacts also rise. The Nakuru Municipality serves as an example of a catchment area that experiences intensive land use. Like other industrial hubs, Nakuru produces a substantial amount of waste. The sewage plants in the region treat both domestic and industrial liquid waste before it is discharged into the lake.
The waste-handling facilities for both domestic and industrial waste have not kept pace with production rates, potentially resulting in the build-up of waste in the environment. Additionally, there is apprehension regarding the impact of increased urban run-off on the lake’s hydrology and pollution levels. Examination of stormwater, sewage, and lake sediment has revealed the existence of heavy metals and pesticide residues, known to pose hazards to birds and mammals.
Conclusion
Field practitioners have observed that Lake Nakuru is facing major issues caused by human activity in its catchment basin. These issues primarily involve water balance and quality. At present, different technical solutions are being proposed and put into action. These solutions include improving population planning and distribution, restoring ground cover in the catchment area, practicing better soil management, decreasing the use of agrochemicals, and implementing improved handling and disposal methods for urban and industrial waste. However, in order for these efforts to achieve long-term success, it is essential to create a supportive environment and establish a clear link between development policy and environmental conservation.
It is essential to implement and institutionalize moral concepts like “sustainable development” to tackle environmental issues. Moreover, it is crucial to improve existing environmental policy and legislation while addressing economic and social challenges. Poverty is widely recognized as a factor that both contributes to and exacerbates environmental problems.
The challenges of equity, security, and political stability are crucial to be resolved in order to achieve sustainable development in the foreseeable future.
