Ondiri Swamp - Kenya’s Only Quaking Bog and the Second Deepest Wetland in Africa
The Southern Bypass has crossed many topographical regions on its path around the city. The 17.1 billion project begins from Mombasa Road to Kikuyu. One of the fascination structures is the 121m box culvert that will allow the smooth flow of water from the Ondiri Swamp a few metres across that is the only quaking bog and the second deepest wetland in Africa after Doula in Cameroon.
Truant boys dig off the macrophytes making a hole in which they dive and swim underneath the floating peat. If you do not identify the light from where you dived in, you will float away to darkness. - Mr.Wainina of MCDI (Standard Digital)
The MegaProjects Kenya team incharge of this the Southern Bypass project came across this interesting swamp that has a history dating back to the colonial times. Ondiri swamp lies at some 1km from the Kikuyu township and is an important source of the Nairobi river. This swamp difers from any other because it has a covering of macrophytes growing above the water. This mud like cover known as peat can hold a human being's wight at some points on the surface and a jump on the surface sets of a series of waves across, a clear sign that one is 'standing on water'.
The peat has some grass cover which has fooled some to forget and plunge into the deep dark waters below. A series of wood planks has been laid ontop to aid in crossing accross but at some point in the middle of the lamp one has to be careful.
Ecosystem destruction in Ondirí wetland dates back to the colonial era, which was marked by extensive deforestation. Currently the ecosystem is highly threatened by various activities within both the wetlands and riparian land. This includes dumping of solid waste and uncontrolled water abstraction. There are several water pumps around the wetland, which are not metered meaning that it is impossible to gauge the level of water abstraction.
In addition, there are fears that the water in the wetland has been reducing. But again the out flowing river does not have a gauging station. Kikuyu town also lacks a sewerage system, which increases the likelihood of pollutants seepage from septic tanks. Previous conservation initiatives mainly fencing and tree planting by forest departments in the 1990’s collapsed due to lack of community ownership of the process and enforcement.
The Ondirí wetland is oval in shape and local legend has it that it used to be an open lake in the early part of the last century and indeed the name itself is Gikuyu corruption of old lake (Undirí). However as deforestation and subsequent erosion accelerated, the lake came to be covered with floating reeds on peat such that now it has an extensive reed mat that covers more than 95 percent of the wetland to form a quacking bog, the only one in the country. A quacking bog is made up of a layer of vegetation floating over water. You can walk on the vegetation, but if you jump up and down the whole bog quakes (Macharia and Thenya, 2007).
Ondirí is a unique and an important wetland. As noted earlier, Ondirí is Kenya’s only quaking bog and the second deepest wetland in Africa after Doula in Cameroon. But despite the size and benefits of Ondirí wetland to this country it has received only scant attention from researchers, writers, natural resource environmental management and the large conservation driven organizations. Equally the governments both central and local have done little to conserve the wetland for posterity. Media mention of this wetland is also scattered and limited in scope.
The major diatoms at Ondiri Swamp were Amphipleura pellucida, Navicula gawaniensis, Pinularia tropica, Eunotia tenella, Melosira ambigua, Nitzschia subrostrata, Surirella sp., Eunotia pectinalis, Cyctotella iris, Nitzschia latens and Strauroneis phoenicenteron which are mainly associated with larger and more open wetland. The younger level was dominated by Navicula tenella, Navucula el Kab, Nitzschia linearis, Navicula halophila, Gomphonema gracile, Navicula. salinicola, Frustulia rhomboides Eunotia pectinalis and Hantzschia amphioxys which are associated with smaller wetlands.
References: Paleoclimate of Ondiri Swamp - Julian Awuor Ogondo, Standard Media