A Guide to Wetlands in Kenya
What is a Wetland?
Wetlands are perceived as those ecosystems that integrate the characteristics of terrestrial and aquatic environments, that is, water, soil and vegetal profile. The degree to which these properties are combined exhibits spatial, temporal and wetland types. The latter accounts for the broad definitional base contained in the Convention on Wetlands of International Importance, notably of waterfowl habitat, more proper the Ramsar Convention whose overarching aim is to stem the progressive encroachment on and loss of wetlands. The Ramsar Convention describes wetlands as “areas of marsh, fen, peatland or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water the depth of which at low tide does not exceed 6 ms”. Instructively though, this definition does not encompass permanent, deep water bodies and courses, although it includes shallow areas near the shorelines and riverbanks. Kenya acceded to the Ramsar Convention and it came into force in the country on October 5, 1990. Kenya Wildlife Service (KWS) is designated as the convention’s implementing authority and national focal point. Wetlands cover about 6% of the Earth’s surface area. Although the exact extent of Kenya’s wetlands is unknown, owing to the lack of a wetlands inventory, they are estimated to occupy around 3 to 4% of Kenya’s land mass although this can temporarily increase to 6% during the rainy seasons (Kenya Wetlands Forum 2012). Despite their modest geographic extent, the wetlands around the world provide a number of important ecosystem services which are indispensable to humans and biodiversity’s very survival, salubrity, and welfare.
Variations of Wetlands in Kenya
Ramsar classification of wetland types contains three broad categories: inland; marine and coastal; and man-made. These are then sub-divided into 42 types. Owing to Kenya’s diverse climate and topography, it’s home to 6 wetland types: riverine; lacustrine; palustrine; estuarine; marine; and human-made wetlands. Riverine wetlands occur along rivers and streams. They are common along the country’s main watercourses, the most important of these being Athi, Ewaso Ng’iro, Nyando, Yala and Tana Rivers, although the latter is covered in detail under the estuarine category of wetlands. Lacustrine wetlands occur in and around lakes and are predominantly influenced by these water bodies, whether these are fresh or saline. As lakes are situated in topographic depressions, water is the key feature and they typically lack trees, shrub and persistent emergents. Although lacustrine wetlands are common in the Lake Victoria basin and Rift Valley region, they also occur in craters, for instance Lakes Simbi and Sonachi (Crater Lake), Mount Kenya’s Lake Alice, Tyndall, Hut Tarn, and Hanging Tarn.
All of the five locations in the country that have been designated as Wetlands of International Importance (Ramsar Sites) are lakes (Nakuru, Naivasha, Bogoria, Baringo and Elementaita) all part of the Great Rift Valley system, and lacustrine wetlands by nature. Moreover, all these lakes are important bird habitats and are renowned for their large flamingo populations. As such, they are frequently visited by ornithologists, making them an important component of the tourist circuit. While Baringo and Naivasha are freshwater lakes, Nakuru, Bogoria and Elementaita are alkaline. These relatively shallow lakes collectively expand over an area of 1,018 km2. Palustrine wetlands comprise marshes, swamps, bogs and floodplains. As these lack flowing water and are generally speaking non-tidal, a defining characteristic is that they are typified by persistent emergent wetland plants such as Cyeprus papyrus. Many small palustrine wetlands in the country serve as insular habitat islands in the centre of heavily populated areas. Others serve as agricultural land such as the King’wal Swamp in Nandi County and Nyando floodplain in Kisumu County. Estuarine wetlands occur where fresh and salty water mix, to include deltas, tidal-marsh and mangrove swamps.
Kenya’s estuarine wetlands inventory includes those in the Tana River Delta, at Mombasa, Shimo La Tewa, Kilifi, Turtle Bay as well as the islands of Lamu, Pate and Manda. Marine wetlands are those that are exposed to the waves and currents of the open ocean and as such display a high level of salinity typically exceeds 3%. Kenya’s marine wetlands portfolio is consisted of lagoons, shingle beaches, mangroves, rocky shorelines, salt marshes, mudflats, sea beds and coral reefs, with each of these exhibiting unique hydrological and topographical attributes. For example, while the country’s sea grass beds predominantly occur in shallow reef slopes and sandy beaches are associated with coastal areas that are dominated by terrigenous sediment but without fringing reefs, coral reefs occur further seaward, around the Marine Protected Areas (MPAs) such as the Mombasa Marine National Park and Malindi Marine National Park & Reserve. Kenya’s human-made wetlands comprise a number of disparate artificial structures. These include water impoundment for irrigation (such as the Mwea, Ahero and Bunyala irrigation schemes) or hydroelectric power generation with the attendant major dams, principally of the Seven Forks Hydro-Power Project.