Browsing by Author "Olilo, Casianes"
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Publication Composition and design of vegetative filter strips instrumental in improving water quality by mass reduction of suspended sediment, nutrients and Escherichia coli in overland flows in eastern escarpment of Mau Forest, Njoro River Watershed, Kenya(Springer Link, 2016-06-13) Olilo, Casianes; Onyando, Jack; Moturi, Wilkister; Muia, Wairimu; Roegner, Amber; Ogari, Zachary; Ombui, P.; Shivoga, WilliamThis study assessed the effect of vegetative filter strip (VFS) in removal of suspended sediment (SS), total nitrogen, total phosphorus and Escherichia coli (E. coli) in overland flow to improve receiving water quality standards. Four and half kilograms of cowpat manure was applied to the model pasture 14 m beyond the edge of vegetated filter strip (VFS) comprising 10-m Napier grass draining into 20-m Kikuyu grass (VFS II), 10-m Kikuyu grass draining into 20-m Napier grass (VFS III) and native grass mixture of Couch–Buffel (VFS I-control). Overland flow water samples were collected from the sites at positions 0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25 and 30 m along the length of VFSs. E. coli removal by Napier grass VFS was on the order of log unit, which provided an important level of protection and reduced surface-flow concentrations of E. coli to below the 200 (CFU 100 mL−1) recommended water quality standards, but not for nutrients and SS. The Napier grass showed highest efficiency (99.6 %), thus outperforming both Kikuyu grass (85.8 %) and Couch–Buffel grasses VFS (67.9 ± 4.2 %) in removing E. coli from overland flow. The low-level efficiency of native Couch–Buffel grasses in reducing E. coli in overland flow was because of preferential flow. Composition and design of VFS was instrumental and could be applied with a high potential of contracting the uncertainty in improving water quality standards through mass reduction of SS, nutrients and E. coli load in watersheds.Publication Lakes Baringo and Naivasha: Endorheic Freshwater Lakes of the Rift Valley (Kenya)(Springer, Dordrecht, 2018-05-16) Omondi, Reuben; Ojwang, William; Olilo, Casianes; Mugo, James; Agembe, Simon; Ojuok, Jacob E.Lakes Baringo and Naivasha are among the Great Rift Valley lakes that were formed about 25 million years ago by violent separation of two of the earth’s continental plates floating on the molten magma of its core. Lake Baringo is a freshwater lake in the eastern arm of Kenya’s Great Rift Valley, with surface and catchment areas of approximately 130 and 6,820 km2, respectively, and a mean depth of 5.9 m. The lake is shallow and is virtually a wetland in its entirety, with submerged Ceratophyllum demersum occurring in the deepest portions of the lake. However, larger marshes are found at the river mouths to the south and east. Lake Naivasha has a surface area of approximately 119,130 km2, a catchment area of 3,200 km2, and a mean depth of 4.1 m. Lake Naivasha’s water level has experienced great fluctuations sometimes as much as 7 m over many years attributed to large-scale climatic influence, also causing changes in water geochemistry. The main lake has a fringing vegetation of Cyperus papyrus and other macrophytes and the lake body supports a diverse macrophyte community. In addition to the lakes’ high biodiversity, they provide water to the local communities for domestic, irrigation, and industrial purposes. Fish in these lakes contribute to the diet of the local communities and are a source of income. Due to their unique scenery and biodiversity, the lakes are destinations for both local and international tourists. Lakes Baringo and Naivasha are faced with numerous threats and challenges including an increasing human population, deforestation and erosion, pollution, impacts associated with tourism, human–wildlife conflict, impact of invasive species, and climate change. Investments around these lakes need to be balanced against the threats to biodiversity and the human population.