Natural Resources Management

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Browsing Natural Resources Management by Funder "National Research Fund"

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    Assessment of land use/land covers changes linked to oil and gas exploration: Developments under changing climatic conditions in Lokichar Basin, Turkana County
    (2020) Kariuki, David Mugendi; Mireri, Caleb; Kibwage, Jacob; Oyoo, Daniel
    Understanding land use/land cover changes(LU/LC) linked to oil and gas exploration under changing climatic conditions in South Lokichar Basin is crucial.This knowledge will inform policy makers on appropriate sustainable vegetation cover management strategies for the sake of pastrolism practiced in the area.The LU/LC changes were assessed using multi-spatial and multi-temporal remotely sensed imageries acquired through Landsat 5TM and Landsat 8OLI/TIRS by use of ArcGIS.The study assessed medium resolution spatial imageries acquired for the area in both rainy and dry seasons,before oil and gas exploration developments begun in South Lokichar Basin between 2006-2011 and after commencement between 2012-2017.The study established that the average area in hectares under vegetation cover had declined since oil and gas exploration developments begun.A one sample t-test statistics indicated that the area under forest,shrubland and grassland cover had significantly reduced at 90% confidence interval with a p-value of 0.072,0.074 and 0.061 respectively.The study established a decline in NDVI from 1 to 0.433 for the rainy season and 0.411 to 0.122 for the dry season between 2006 and 2017 with a p-value of 0.009 <0.05 on paired t-test implying a significant change on vegetation cover.Sustainable management of vegetation cover is important to safeguard livestock forage.
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    Publication
    Effects of Land Fragmentation on Food Security in Three Agro-ecological Zones of Embu County in Kenya
    (Asian Journal of Agricultural Extension, Economics & Sociology, 2017) Ndirangu, Samuel N.; Mbogoh, Stephen G.; Mbatia, O. L. E.
    Land fragmentation is a common agricultural phenomenon in many countries where a single largefarm is subdivided into a large number of separate small land plots. This paper is based on a studythat was carried out to evaluate the impact of land fragmentation on food security in three agroecologicalzones (AEZs) of Embu County in Kenya from January to November 2016. The studyused data collected from 384 farm-households that were randomly selected from three AEZs in theEmbu County, using the 4-stage cluster sampling method. The AEZs were the Sunflower-CottonZone, the Coffee Zone and the Tea Zone, based on the official AEZs classification system in Kenya.Household caloric acquisition method was used to compute a household food security index (HFSI)that was used to measure the household food security status. The effect of farm size on foodsecurity was evaluated using the Binary Logit Regression method. The results showed that theaverage number of people in a household was 3.73 in the Tea Zone, 3.59 in the Coffee Zone and3.93 in the Sunflower Zone, and that farm size had a positive and significant effect on food securityin the Sunflower (P=.029) and Tea zones (P=.007), but not in the Coffee Zone (P=.365). Further, itwas found that the minimum farm-size that could ensure the attainment of the minimum (cut-off)point for household food security (HFSI = 1) was above 2 ha in the Sunflower Zone and 0.5 ha inthe Tea Zone. Based on the study findings, it is recommended that further fragmentation of farmsbelow 0.5 ha in the Coffee and Tea zones and 2 ha in the Sunflower Zone should be discouraged toensure sustainable food security in the study area. For the farms that are already below theminimum cut-off size for food security, measures to increase these farms’ productivities so that theycan support more people per ha should be devised and implemented.
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    Influence of land use and land cover changes on groundwater recharge and pollution in stony Athi Subcatchment, Kajiado County, Kenya
    (Kenyatta University, 2023) Mathenge, Morris Wahome
    The global economic growth and population increase has translated into increased anthropogenic land use and land cover changes. Changes in land use and land cover have the potential of altering the hydrological cycle. In the Stony Athi sub-catchment of Kajiado County, Kenya, demographic pressure and urbanization have transformed natural rangelands into agricultural, industrial and real estate developments. The objective of this study was to investigate the influence of land use and land cover changes on groundwater recharge and pollution vulnerability between 1984 and 2017. Specifically, the study was undertaken to; (a) quantify the spatial-temporal extent and magnitude of land use and land cover changes that have occurred in Stony Athi subcatchment between 1984 and 2017; (b) to estimate the spatial-temporal variations of groundwater recharge due to land use and land cover changes; and (c) to evaluate the influence of land use and land cover changes on groundwater vulnerability to pollution. Quantification of spatial-temporal extent and magnitude of land use and land cover changes was achieved by classifying four satellite images through the supervised classification algorithm and finally applying post-classification change detection technique. Results showed significant (p < 0.05) land use and land cover changes between 1984 and 2017 with an increase in built-up areas (0.04% - 3.4%), agricultural land (0.06% - 0.7%) and grasslands (58.2% - 71.6%), but a decrease in shrub land (37.1% - 21.1%) and forested areas (2.5% - 1.4%). Estimation of the spatial-temporal variation of groundwater recharge due to land use and land cover changes was done using WetSpass-M, a Geographical Information System-based Hydrologic Model. Results indicated a decrease in groundwater recharge from 13.8% in 1984 to 13.2% in 2017. However, the observed temporal variations were not significant at p < 0.05. Spatial variations of groundwater recharge indicated that the highest recharge occur in forested areas at 251.1 mm per year while the lowest recharge occur in bare land at 0.4 mm per year. A modified DRASTIC model was used to evaluate the influence of land use and land cover changes on groundwater vulnerability to pollution. Potential of groundwater pollution vulnerability was categorized using a vulnerability index based on the United States Environment Protection Agency classification. Results indicated that 87% of the study area remained under low vulnerability between 1984 and 2017. Areas under moderate vulnerability decreased from 12% to 9% while areas under high vulnerability increased from 1% to 4% over the same period. The observed temporal variations in groundwater pollution vulnerability were not significant at p < 0.05. It was concluded that the land use and land cover changes in the study area have an influence on groundwater recharge and its vulnerability to pollution, though not statistically significant at p < 0.05. This study recommends continuous monitoring of groundwater quantity and quality, not only in the study area, but also in areas undergoing rapid changes in land use and land cover. Such monitoring will contribute to sustainable groundwater resource management. Future research could focus on other factors, which might affect groundwater dynamics in the study area such as climate change.