Browsing by Author "Ogendi, George Mokua"

Now showing 1 - 3 of 3
  • Publication
    Publication
    Application of the Carlson’s Trophic State Index for the Assessment of Trophic Status of Lake Simbi Ecosystem, a Deep Alkaline-Saline Lake in Kenya
    (International Journal of Fisheries and Aquatic Studies, 2019-08) Opiyo, Stephen; Getabu, Albert Mochache; Sitoki, Lewis Morara; Shitandi, Anakalo; Ogendi, George Mokua
    Eutrophication is increasingly becoming the greatest threat to the ecological health of global water resources hence constant screening of the trophic state of these ecosystems is important. This study was aimed at defining the trophic status of Lake Simbi through the Carlson’s Trophic State Index (CTSI) which is based on the interactions of three water quality variables viz., Secchi depth (SD), total phosphorus (TP) and the chlorophyll-a (Chl-a). The classification scale for Trophic State Index (TSI) runs from 0 to 100, and the results of this study showed that the mean TSI for SD was 67.60, for TP was 118.56, for Chl-a was 74.86 and finally the overall CTSI was 87.01. These show that Lake Simbi is hypereutrophic which reflects the high concentration of nutrients in the lake. The lake suffers from cultural eutrophication which symptomatically manifests in the prevalent proliferation of algal bloom in the lake. The study therefore recommends adoption of an efficient multi-sectoral plan for monitoring and controlling nutrients loading and other pollutants input into the lake.
  • Publication
    Publication
    Mapping of Groundwater through the Integration of Remote Sensing and Vertical Electrical Sounding in ASALs: A Case Study of Turkana South Sub-County, Kenya
    (Scientific Research, 2019-11-07) Nyaberi, Daniel Mogaka; Basweti, Evans; Barongo, Justus Obiko; Ogendi, George Mokua; Kariuki, Patrick Chege
    Turkana South Sub-County falls in the arid and semi-arid lands of Kenya, which are characterized temperatures of 20°C to 41°C with an average of 30.5°C and precipitation in the range of 52 mm to 480 mm per year. The area has limited availability of water resources. The area has a land surface of 18,000 km2 and lies between Longitudes 35°10'00" and 36°45'00" East and between Latitudes 1°0'00" and 3°0'00" North. The study area faces immense difficulties in trying to meet its water requirements for her rapidly increasing populace, livestock needs and other developmental programmes. Surface water in the area is becoming unobtainable, thus the choice of groundwater exploitation. Indeed with the snowballing demand necessitated by energy, agricultural and livestock production needs in this area, there is an appeal into investigation for groundwater in this greatly remote and extensive area. Thus, the success in the exploration, development and management of groundwater in such a large area calls for such methods that can easily be used to zero down to exploitable targets. Given the expansiveness of the study area, remote sensing (RS) has been used to map lineaments which in turn have been used to deduce faulting affecting the geology of the area. The mapping by RS helped in identifying weathered zones, the fracture systems and fault zones sign of deeper weathered zones which are interpreted to be potential areas since mainly water is stored within fractures and the weathered zones in subterranean and in hard rocks. In the field topographic expressions of faults and fractures which include; joints, fractures, scarps, river channels and slope breaks were mapped and it was observed that there was a comparison of the features to the coincidence raster and aspect interpreted lineaments. The earmarked points were later investigated using vertical electrical sounding (VES) to establish their feasibility for groundwater availability and extraction. The investigated VES points in areas of high lineament density revealed decreasing resistivity with increasing depth of investigation, a confirmation of faulting. The data presented curves, type KH, type KK, and type Q. Further investigation was done in points of low lineament density, considered to be least affected by faulting and deep weathering, which turned out to be having increasing resistivity with increasing depth of investigation, an indication of layered lithology. The zones of low lineament density are represented by a type A curve, a type H curve, type HH. There is a good agreement in the results of remote sensing data and VES data models generated where the high lineaments density points concur with areas of good groundwater potential.
  • Publication
    Publication
    Mapping of Groundwater through the Integration of Remote Sensing and Vertical Electrical Sounding in ASALs: A Case Study of Turkana South Sub-County, Kenya
    (Scientific Research, 2019-11-28) Nyaberi, Daniel Mogaka; Basweti, Evans; Barongo, Justus Obiko; Ogendi, George Mokua; Kariuki, Patrick Chege
    Turkana South Sub-County falls in the arid and semi-arid lands of Kenya, which are characterized temperatures of 20˚C to 41˚C with an average of 30.5˚C and precipitation in the range of 52 mm to 480 mm per year. The area has limited availability of water resources. The area has a land surface of 18,000 km2 and lies between Longitudes 35˚10'00" and 36˚45'00" East and between Latitudes 1˚0'00" and 3˚0'00" North. The study area faces immense difficulties in trying to meet its water requirements for her rapidly increasing populace, livestock needs and other developmental programmes. Surface water in the area is becoming unobtainable, thus the choice of groundwater exploitation. Indeed with the snowballing demand necessitated by energy, agricultural and livestock production needs in this area, there is an appeal into investigation for groundwater in this greatly remote and extensive area. Thus, the success in the exploration, development and management of groundwater in such a large area calls for such methods that can easily be used to zero down to exploitable targets. Given the expansiveness of the study area, remote sensing (RS) has been used to map lineaments which in turn have been used to deduce faulting affecting the geology of the area. The mapping by RS helped in identifying weathered zones, the fracture systems and fault zones sign of deeper weathered zones which are interpreted to be potential areas since mainly water is stored within fractures and the weathered zones in subterranean and in hard rocks. In the field topographic expressions of faults and fractures which include; joints, fractures, scarps, river channels and slope breaks were mapped and it was observed that there was a comparison of the features to the coincidence raster and aspect interpreted lineaments. The earmarked points were later investigated using vertical electrical sounding (VES) to establish their feasibility for groundwater availability and extraction. The investigated VES points in areas of high lineament density revealed decreasing resistivity with increasing depth of investigation, a confirmation of faulting. The data presented curves, type KH, type KK, and type Q. Further investigation was done in points of low lineament density, considered to be least affected by faulting and deep weathering, which turned out to be having increasing resistivity with increasing depth of investigation, an indication of layered lithology. The zones of low lineament density are represented by a type A curve, a type H curve, type HH. There is a good agreement in the results of remote sensing data and VES data models generated where the high lineaments density points concur with areas of good groundwater potential.