Kenya: A Natural Outlook PDF Download

Author: Andreas B. Brink
Publisher: Elsevier Inc. Chapters
ISBN: 0128083905
Category : Science
Languages : en
Pages : 40

View

Book Description
Monitoring vegetation dynamics and land cover change in Kenya are essential for the sustainable management of natural resources and biodiversity conservation. However, accurate status of seasonal variation in vegetation and long-term land cover change data valid at the regional and country level generally do not exist or are hard to obtain. Here, we describe the various ecological regions of Kenya and the associated rainfall and land cover patterns of each ecological zone. This includes the use of low-resolution satellite data time series to characterise for each ecoregion and land cover type the interannual variability of the vegetation cycle, including the start-, mid- and end of the growing season. Seasonal variation in vegetation phenology is mapped to highlight the areas of greatest interannual variation and compared to rainfall patterns over the focal study period. Statistical estimates of land cover change are produced for six broad classes for the years 1990, 2000 and 2010, based on detailed land cover change assessed by a systematic sampling of high-resolution satellite imagery. Rates of change for Kenya are presented and discussed in light of the low-resolution time series analysis. Results highlight information on land cover change processes such as vegetation dynamics and deforestation. These are discussed within the context of the drivers of changes to the natural ecosystem—their potential impact on land availability for human activities such as agriculture and logging for timber and fire wood production on the one side and habitat and biodiversity conservation on the other side. Finally, biodiversity and habitat value, ecosystems and threats are analysed for Kenya’s conservation and protected areas so as to identify the status of and pressures on the country’s protected areas. Six indicators of species irreplaceability, habitat irreplaceability and the level of perceived threat to a protected area’s habitat and species from agriculture and human population are analysed. In addition, high-resolution satellite images taken over conservation areas are used for assessing land cover changes inside protected areas and in the surrounding 20km buffer zone. The results show the importance and effectiveness of protected areas in reducing the loss of natural vegetation and hence protecting the habitats and biodiversity.

Author: Mordecai O. Ogada
Publisher: Elsevier Inc. Chapters
ISBN: 0128083956
Category : Science
Languages : en
Pages : 25

View

Book Description
This chapter examines the challenges facing the management of wildlife and fisheries in Kenya using the historical perspectives of the current systemic weaknesses therein. Statutory institutions managing wildlife and fisheries resources in Kenya still operate under the colonial ‘policing’ model that presumed absence of any local management capacity in situ. Examples are given of unsuccessful attempts to manage wildlife and fisheries resources over the years using interventions that failed to include local human dimensions. The colonial model is thus demonstrated to be still in place but inapplicable to address the current challenges in Kenya. The chapter finally recommends the deliberate inclusion of local communities as intellectual participants to ensure socially and environmentally sustainable management of wildlife and fisheries resources in Kenya.

Author: Norbert Opiyo Akech
Publisher: Elsevier Inc. Chapters
ISBN: 0128083808
Category : Science
Languages : en
Pages : 18

View

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

Author: Christine A. Omuombo
Publisher: Elsevier Inc. Chapters
ISBN: 0128083875
Category : Science
Languages : en
Pages : 13

View

Book Description
The Indian Ocean waters off the Kenyan coast is stratified due to temperature, salinity and pressure differences between the warm less saline less dense surface waters and the deep saline cooler waters. This stratification displays local variations influenced by rainfall or heavy water discharges of the deltas of Tana and Sabaki as well as the monsoon with maximum temperatures during the transition periods of the monsoons when the winds are light and the solar insolation is high. Turbidity increases due to sediment discharges at the mouths of the Tana and Sabaki deltas has been noted with high turbidity during the long rains in April–May and short rains in October–November, the East African Coastal Current transports the sediment northwards to the northern banks with a minimum influence on the water quality south of the coast. Sedimentation rates of 3–4 mg/cm2/day have been recorded from the Galana and Tana deltas where increased concentrations of elements such as Co, Cr, Cu, Ni, Pb, V and Zn have been reported. The semidiurnal tidal regime is influenced by the monsoon winds with the larger waves (>1.5 m) during the southeast monsoons and the lower waves (

Author: Charles Maina-Gichaba
Publisher: Elsevier Inc. Chapters
ISBN: 0128083816
Category : Science
Languages : en
Pages : 15

View

Book Description
Kenya's relief stretches from sea level to just over 5000m at the peak of Mt. Kenya. Combined with its tropical latitudinal location, this relief range creates varied physical environment with characteristics that are almost equatorial sharply contrasting with semi-arid and arid environments. Topography is described as both simple and diverse. Its simplistic form is shown by the fact that the relief can easily be separated into lowlands and uplands while diversity is exemplified by the presence of varied landform types which include Equatorial, Savannah, Aeolian, Glacial, Volcanic and Tectonic. The Kenyan landscape, with its wide variety of forms, is closely linked with such factors as climate, micro-climate, water supply, soils, vegetation and agricultural potential. Some of the sharp contrasts in Kenya’s landscape result from the considerable differences in age of the component landforms. These are now warped and broken by faults in many areas while elsewhere volcanic activity has produced further modifications. Earth movements particularly in late Tertiary, Pleistocene and recent times, have resulted in the formation of the major mountain blocks and Rift Valley systems. These were accompanied by extensive volcanic lava emissions, which cover a significant percentage of the country's land surface. As a consequence of volcanism and earth movements, the drainage has been dislocated, interrupted and modified, and there is hardly a river that has not been affected. Many lakes have been formed in downwarped or downfaulted areas. In coastal regions, the history has been further complicated by Pleistocene changes of sea level. Major physiographic regions seems to be associated with the drainage patterns of the country. A combination of the relief, drainage systems and physiographic regions seem to influence the management and planning of the country’s development strategy. The policy makers must therefore design projects and programs for information gathering, analysis and dissemination on the basis of physical geographic factors as well as the man-made innovative improvements of nature. A superimposition of these attributes through Geographic Information System may show areas that are likely to give the greatest production-increasing effects on the basis of a combination of all the resident attributes.

Author: Dorothy Wanja Nyingi
Publisher: Elsevier Inc. Chapters
ISBN: 0128083948
Category : Science
Languages : en
Pages : 27

View

Book Description
Freshwater ecosystems of Kenya are the lifeline of economic and social development; however, most of these are threatened or on the verge of collapse. The need to maintain them in their natural condition, reduce disturbance and conserve their biodiversity has been stressed in the face of severe drought, food insecurity and water stress conditions including inability to maintain constant hydroelectric power. However, without a clear picture of how many freshwater rivers, wetlands and lakes exist and their precise locality, size, sources and uses, it would be impossible for the authorities charged with their protection to put in place management or mitigation measures. Highland freshwater ecosystems of Kenya include Mount Kenya, Aberdares, Mau Forest, Mount Elgon and Cherangani Hills, which are referred to Kenya's water towers since they jointly supply most of the freshwater resources of the country. They are fragile ecosystems with streams flowing through montane forest belts and are critical reservoirs of biodiversity. They are characterized by high rainfall; steep slopes and erodible soils induce severe surface runoff, soil erosion and landslides. Sediments from erosion cause pollution of water in the streams. In countries with limited resources such as Kenya only small portions of rivers can be effectively conserved. It is imperative that significant effort is targeted at the upper reaches, because any conservation effort in the lower reaches of the river are easily negated by upstream disturbances. Their importance is primarily due to their ability to store and distribute water to lowlands and for ground water recharge. For example, 90% of dry season flow of the Northern Ewaso Ng'iro River is derived from the Mount Kenya. Montane areas in Kenya are also often associated with sacred sites and areas of cultural and social importance to the communities around them. Kenya's highland ecosystems face great anthropogenic threats due to deforestation and agricultural pressure. These areas have been ideal for tea and coffee plantations and human settlements. The Mau Forest, which is the largest indigenous forest in Kenya, has had vast areas cleared for settlements by immigrants, which in turn has caused reduction of flows of the Sondu Miriu River, which is dammed downstream for hydroelectric power. Even though sections of the Aberdares and Mount Kenya occur in protected areas, the lack of management and inability to patrol large areas has had led to various conflicts over land and water uses. Lowland freshwater ecosystems include those occurring on the lower sections of the eastwards-flowing rivers of Kenya including Rivers Tana, Athi, Northern Ewaso Ng'iro and the Ramisi. These are areas of low altitude and the rivers are slow moving and characterized by high sediment load, which is rich in nutrients and important for agriculture along the banks of these rivers. However, reductions and changes in flow regimes in the lowlands are more recently becoming a reason for concern. In the Tana River Delta, a large number of communities and biodiversity rely on the water for agriculture, pastoralism, fishing and other socioeconomic uses related to ecosystem services. The two main factors affecting river flows in lowlands are water abstractions and land-use change and intensification, both related to growing human populations. Climate change poses a further complication to both highland and lowland ecosystems due to changes in rainfall patterns reducing not only river flows but also the high rainfall events that cause unprecedented floods.

Author: Michael E. McClain
Publisher: Elsevier Inc. Chapters
ISBN: 0128083859
Category : Science
Languages : en
Pages : 23

View

Book Description
Freshwater is key to Kenya’s socioeconomic development but also essential for maintaining environmental integrity and human welfare. Here, we report the results of a comprehensive and collaborative assessment of the ecological status of the Mara River and the environmental flow regime needed to sustain the ecological function of the river and related systems in the Mara/Serengeti Ecoregion. Field surveys indicate only modest evidence of degradation based on the geomorphology of the river channel and the presence and vitality of select indicator riparian plants, fish, and macroinvertebrates. Environmental flow recommendations were based on hydraulic modelling and field observations and were determined through a consensus building process involving members of the research team. During normal rainfall years, recommendations range from average monthly values of 1.3 to 15.0m3 s−1. During drought years, the respective recommended flows are 0.3 to 6.0m3 s−1. These recommendations fall between the 45th percentile of monthly flow durations curve during wet months of normal years and the 98th percentile of the annual flow duration curves during drought years. Recommended floods range from 2-day events of 12m3 s−1 to an annual 3-day flood of 90m3 s−1. Results of the assessment suggest that during years of normal rainfall there is sufficient flow in the river to allow additional water extractions and still meet environmental requirements, but environmentally friendly storage is needed and uncontrolled abstractions could easily exhaust the available resource. During drought years, however, the river may already drop to flows incapable of simultaneously meeting both extractive water demands and environmental flow recommendations.

Author: Daniel O. Olago
Publisher: Elsevier Inc. Chapters
ISBN: 0128083824
Category : Science
Languages : en
Pages : 13

View

Book Description
The Quaternary evolution of Kenya is set in a dynamic climatic, environmental, volcanic and tectonic context. Climate has been controlled by orbital forcing with a dominant precessional cycle of 23,000 years driving hydrological changes that have had dramatic impacts on lake levels. Climate has interacted with tectonism and volcanism to continually modify the landscapes and environments, partly influencing hominin, animal and plant evolution. The most prominent feature is the Rift Valley, whose evolution was associated with flood volcanism, rift deformation and migration, formation of caldera volcanoes and the rise and establishment of many lakes, up to about 0.3 Ma. In the western part of the country, Lake Victoria arose in the Middle Pleistocene as a consequence of rift margin uplift and resulting river reversal and ponding. In the eastern part of the country, the landscape is dominated by the Plio-Pleistocene evolution of Mount Kenya and the Nyambeni Volcanic Series which comprises of a large field of basaltic cones and vents that extend to the arid to semi-arid northern part of the country. Several factors such as the tectonic evolution, climate, wave and tidal regime, marine transgressions and regressions, sedimentation and river discharge control the geomorphology of the Kenyan coast. Geomorphological features include dune sands, coral reefs and terraces which indicate that sea level was above present levels at least four times during the Pleistocene.

Author: Josphat K. Mulwa
Publisher: Elsevier Inc. Chapters
ISBN: 0128083972
Category : Science
Languages : en
Pages : 36

View

Book Description
The East African Rift System (EARS) and by extension the Davie Ridge, which is considered as the seaward extension of eastern branch (Kenya Rift Valley) of the East African Rift Valley (), are characterized by divergence whose maximum rate is estimated to be about 7mm/year (). This rate of divergence is somewhat much slower than that found at most active mid-ocean ridges or even the convergence of India–Burma plates or that between the Australian and Sunda plates (). Despite this slow rate of divergence, the East African Rift Valley and the Davie Ridge are characterized by frequent seismicity with large and shallow earthquakes occurring occasionally. Seismic reflection, gravity, and magnetic data from offshore East Africa allow the Davie Fracture Zone to be traced from 11oS to its intersection with the Kenyan coast at 2oS, constraining the relative motion of Madagascar and Africa (). Further, numerous faults and fractures probably associated with the Davie Fracture have been mapped using recent gravity and magnetic data between latitudes 2o21′S and 3o03′S and longitudes 40o08′E and 40o45′E by . Seasat-derived free-air gravity anomalies and slope/rise positive magnetic anomalies observed in shipboard data help to locate the continent–ocean boundaries (COB) off the shore of East Africa and Madagascar. Furthermore, the EARS, and precisely the Kenya Rift Valley, is characterized by ~3-km-thick sediments and normal-faulting mechanism. Deformation has been active along the Kenya Rift Valley as evidenced by high seismic activity. Surface deformation studies from SAR interferometry in the southern sector of the Kenya Rift Valley in Magadi show that it is characterized by 14cm of deformation over 10-km-long stretches (). If the Davie Ridge is an extension of the East African Rift Valley, we cannot rule out the occurrence of tsunami-generating earthquakes, which are bound to have devastating consequences on the eastern coast of Africa. Earthquakes as deep as 40km have been recorded below Davie Ridge (). However, evaluation of recent seismic data shows that magnitude 6.0–7.2 earthquakes at relatively shallow depths of 10–30km are a common occurrence along the Kenya Rift Valley and the Davie Ridge in the Mozambique Channel. The focal mechanism of these earthquakes supports what has previously been proposed that the Davie Ridge is a southward extension of the eastern arm of the EARS. The earthquake focal mechanism indicates that the Davie Ridge is characterized by predominantly normal faulting with occasional oblique faulting. Consequently, Kenya and generally the East African coast are prone to both seismic hazards on land and tsunami-generating earthquakes. This chapter begins with general overview of the seismicity in Kenya from the 1900s to the present. Seismicity in Kenya up to 1963 is mainly based on macroseismic data while that from 1963 to the present is based on data from instrumental recordings. In the past, a number of microseismic and seismicity studies in Kenya have previously been undertaken and the results from these studies are rather disjointed. In this chapter, we have made an attempt to merge all the existing results into one database from which the general seismicity, and subsequently seismic hazard in Kenya has been evaluated. The main goal of this chapter is to bring into focus the area(s) in Kenya more prone to seismic hazards either due to ground shaking occasioned by an earthquake or due to tsunami as a result of earthquakes occurring along the Davie Ridge.

Author: Ilaria Palumbo
Publisher: Elsevier Inc. Chapters
ISBN: 0128083921
Category : Science
Languages : en
Pages : 18

View

Book Description
In this chapter, we discuss the ecological role of fire and how this is relevant to biodiversity and park management. We summarize the role fire has in different types of ecosystems and why conservation programmes would benefit from including fire plans. We present the fire activity in the Kenyan protected areas between the years 2002 and 2012. The information is derived from satellite observations and processed to show the fire seasonality and how fire occurrence is distributed in different vegetation classes. We also provide insights about how fire can contribute to land-cover change looking at long time series of data.