Natural Resources Management

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Browsing Natural Resources Management by Funder "NRF"

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  • Publication
    Publication
    Effects of Land Use/Land Cover Change and Rainfall Variability on Hydrological Characteristics of River Ruiru Watershed, Kiambu County, Kenya
    (2021-11) Waithaka, Ann
    Watersheds and their water resources are highly vulnerable to land use/land cover changes and seasonal rainfall variability as they directly influence basin hydrological characteristics in terms of water quantity and quality. This study assessed the effects of land use/land cover change and rainfall variability on hydrological characteristics of River Ruiru watershed in Kiambu County. The study integrated the use of remote sensing, Geographic Information System (GIS), water quality sampling, hydrological modelling and statistical methods to collect and analyse the collected data. Results of land use/land cover change analysis indicated that built-up areas, annual crops and perennial crops (tea and coffee) increased by 3.068%, 35.848% and 11.493% respectively between 1976 and 2017. However, it was observed that perennial crops increased gradually between 1976 and 1995 but declined by 1.94% between 1995 and 2017. Grassland, shrubland and forestland declined by 7.48%, 13.25% and 29.79% respectively between 1976 and 2017. Consequently, Soil and Water Assessment Tool (SWAT) model simulation results indicated that the land use/land cover changes that occurred in River Ruiru watershed between 1984 and 2017 had effects on the quantity of river discharge and water quality for drinking purposes. Surface runoff (SURQ), lateral flow (LATQ) and groundwater contribution to discharge (GWQ) increased from 30.25mm/yr, 8.48mm/yr and 9.95mm/yr to 181.25mm/yr, 11.44mm/yr and 10.66mm/yr respectively. Moreover, the nitrates in surface runoff (NO3SURQ), nitrates in lateral runoff (NO3LATQ), Organic Nitrogen (N.ORG) and Organic Phosphorus (P.ORG) increased from 0.05kgN/ha/yr, 0.06kgN/ha/yr, 5.77kgN/ha/yr and 0.87kgP/ha/yr to 1.47kgN/ha/yr, 0.19kgN/ha/yr, 70.60kgN/ha/yr and 8.86kgP/ha/yr respectively. In additions, findings from the study indicated that temporal rainfall variability had effects on the quantity of river discharge and water quality of River Ruiru. Based on regression analysis, the correlation between the observed and predicted value of dependent variable indicated an association of R=0.972 between temporal rainfall variability and quantity of river discharge hence showing a strong positive linear relationship. Similarly, Pearson’s correlation analysis results showed that temporal rainfall variability was strongly and positively correlated to NO3, N.ORG and P.ORG with R=.695, p<.001; R=.781, p<.001 and R=-.780, p<.001. Furthermore, results from a paired sample t-test indicated that pH, turbidity, Dissolved Oxygen (DO), electrical conductivity and Total Dissolved Solids (TDS) had higher mean during wet season (M=8.40, M=79.00, M=51.20, M=87.00 and M=54.20) than in dry season (M=6.80, M=11.60, M=43.40, M=73.00, and M=45.40). The difference for these water quality parameters between dry and wet seasons was significant (P=0.003, P=0.034, P=0.005, P=0.013 and P=0.014). Moreover, findings from the study indicated that DO, TDS, electrical conductivity, total phosphorus and total nitrogen values were within World Health Organization (WHO) and National Environment Management Authority (NEMA) recommended values. However, the results for the total coliforms and E. coli indicated that River Ruiru was severely polluted with faecal organisms. In conclusion, land use and land cover changes and temporal rainfall variability have affected the quantity of river discharge and water quality in River Ruiru watershed. As such, remedial actions to address the hydrological effects of land use/land cover change and temporal rainfall variability both by national and county governments are required.
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    Publication
    Optimization of Nutrients Release Parameters in Synthesized Hydrogel Minerals Anchored Material for Growth of Selected Plants in Embu County, Kenya
    (Kenyatta University, 2020-12) Kiriro, Grace Nduta
    Soil is the natural basis for plants growth as it not only provides support, water and minerals, but also helps to aerate the roots for proper development. However, due to the ever-growing population, available land is becoming a challenge. Urbanization also leads to insufficient surface for food production, as the arable land is used for settlement. This has further been exacerbated by erratic climatic conditions. Due to such limitations, this has compelled other options to be considered. Such options are growing of plants in soilless media that include hydroponic crop production and growing plants in sand, gravel or other liquids where the requisite nutrients are added. These methods allow a more efficient use of water and fertilizers, as well as better control of climate and pest factors. Despite the success in hydroponic production, there are challenges in that there is need for air circulation in the nutrient rich solution, plant support mechanism and disposal of the high concentrated nutrient solution into the environment after use putting a stress to the already stressed natural resource. Due to such limitations, there is a need therefore to come up with a method that will address such challenges. However, growth and propagation of plants for food crop can be made possible in soilless media if suitable conditions are provided. The objective of the study was to synthesize a solid phase nutrient anchored substrate material for growth of selected plants watered by hydrogels of bio origin. The substrate material was synthesized and then characterized using Fourier Transform Infra-Red (FTIR) and Nuclear Magnetic Resonance (NMR) to confirm the modification. Suitable minerals were then anchored by complexation in the substrate material and this was confirmed by X-ray Photoelectronic Spectroscopy (XPS). The release parameter and concentrations of the minerals was investigated using Differential Pulse Anodic Stripping Voltammetry (DPASV) and Flame Atomic Absorption Spectroscopy (FAAS) respectively. The substrate material was watered using hydrogels synthesized by modification of biomass. The modified biomaterials were characterized using Thermo Gravimetric Analysis (TGA), UV –Vis and FTIR spectroscopy. It was observed that mineral released increased with decrease in pH and at a pH value of 5.5, 90% of the nutrients were available for plant uptake. It was found that complexation of Fe2+ had a stability constant of 1.99×1014M-1 . This implies that the nonbiodegradable material has a potential application as a media for plants growth. The swelling ability of the hydrogels was investigated. It was found that the modified biomaterials had superabsorbent properties as the some had a capable of holding 30 times by mass content of water within 5 minutes of exposure. The plant growth media plus each respective hydrogels were then used for the growth of some selected plants (Spinacia oleracea L., Solanum tuberosam L. and Carica papaya). The modified biomaterials had a retention capacity of 90 % for the first 4 weeks of application. It was also observed that growth analysis using the leaf area index were higher on plants grown in 10 g plant growth substrate media watered by 50 g of the celluloseurea and cow dung-urea gels which were found to have an average growth rate of 0.045/wk. This growth was made possible by adequate aeration provided by volume variations of the gel and support provided by the solid particles of the soilless media. The hydrogel watered substrate was done in potted plants as well as in artificial gardens to grow vegetables rich in nutrients and the findings extrapolated for growth of some selected plants in an arid area. Therefore the synthesized materials have a potential application for the growth of crops in arid areas.