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Assessment of Rainfall, Streamflow and Reservoir Level Trends for Malewa River Catchment, Naivasha, Kenya

Received: 19 December 2020     Accepted: 28 December 2020     Published: 12 January 2021
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Abstract

Appropriate water quality and quantity are critical problem greatly affecting significant proportion of the population particularly those living in semi-arid and arid areas. Rainfall characteristics, streamflow and reservoir levels are some of the key hydro-meteorological variables within a catchment in the determination of sufficiency of water quantity. Lake Naivasha reservoir level continues to be hit by anthropogenic stressors such as loss of wetlands, water abstraction and eutrophication. Also there has been a lot of fluctuation in flow discharge of Malewa River over the years where the tributaries (Turasha and Karati streams) usually dries up during dry season. This paper presents the results of a research to assess the time series trends of rainfall, streamflow and lake basin levels data in the catchment from 1980-2018 using Mann-Kendall trend test to assess water quantity status. Monthly stream flow, rainfall and reservoir level data in the catchment were obtained from Water Resources Management Authority (WRMA) and Kenya Meteorological Department (KMD) for the years 1980-2018. Non-parametric Mann-Kendall rank statistics test was used to examine the trend components of hydro-meteorological variables. The P-values were used to test whether the null hypotheses were statistically significant (α<0.05) at a 5% level of significance. Rainfall values had an increasing trend from 2011 onwards but not statistically significant while annual streamflow values had no trend as P-value showed weak evidences to rejected the null hypothesis. Reservoir level had an upward trend in years 1981, 2001, 2003, 2012 and 2018 while downward trends in 1980, 1982, 1984, 1986, 1987, 2000, 2004, 2008 and 2014. From 2010 onwards, in monthly data, there have been upward water levels in the lake as shown by the trend. These show that the hydro-meteorological indicators in the catchment are independently trending, therefore some other factors such as land cover changes or climate changes were adversely affecting the hydrological cycle. These findings are helpful for planning and management in water resource systems such as forecasting water distribution and mitigate flood and drought.

Published in Journal of Civil, Construction and Environmental Engineering (Volume 6, Issue 1)
DOI 10.11648/j.jccee.20210601.11
Page(s) 1-8
Creative Commons

This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.

Copyright

Copyright © The Author(s), 2021. Published by Science Publishing Group

Keywords

Rainfall, Reservoir Level, River Malewa, Streamflow, Trends of Hydro-meteorological Data

References
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[4] Njiru, J., Waithaka, E., & Aloo, P. A. (2017). An Overview of the Current Status of Lake Naivasha Fishery: Challenges and Management Strategies. The Open Fish Science Journal, 10 (1), 1–11. https://doi.org/10.2174/1874401x01710010001.
[5] Cheruiyot, M., Gathuru, G., & Koske, J. (2018). Quantity and Trends in Streamflows of the Malewa River Basin, Kenya. Journal of Environmental Science and Engineering, B (7), 18–27. https://doi.org/10.17265/2162-5263/2018.01.003.
[6] Becht, R., Odada, E., & Higgins, S. (2005). Lake Naivasha: Experience and Lessons learned. ILEC, 277–298.
[7] Mwai, M. D. (2011). Effects of Climate Change and Human Activity on Lake Levels in the Kenyan Rift (Case Study Naivasha). University of Nairobi.
[8] Ruhakana, A. (2016). The Estimation of Lake Naivasha Area Changes Using of Hydro-Geospatial Technologies. Rwanda Journal, 1 (II). https://doi.org/10.4314/rj.v1i2S.3D.
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Cite This Article
  • APA Style

    Elizabeth Wambui Nyokabi, Raphael Muli Wambua, Romulus Okoth Okwany. (2021). Assessment of Rainfall, Streamflow and Reservoir Level Trends for Malewa River Catchment, Naivasha, Kenya. Journal of Civil, Construction and Environmental Engineering, 6(1), 1-8. https://doi.org/10.11648/j.jccee.20210601.11

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    ACS Style

    Elizabeth Wambui Nyokabi; Raphael Muli Wambua; Romulus Okoth Okwany. Assessment of Rainfall, Streamflow and Reservoir Level Trends for Malewa River Catchment, Naivasha, Kenya. J. Civ. Constr. Environ. Eng. 2021, 6(1), 1-8. doi: 10.11648/j.jccee.20210601.11

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    AMA Style

    Elizabeth Wambui Nyokabi, Raphael Muli Wambua, Romulus Okoth Okwany. Assessment of Rainfall, Streamflow and Reservoir Level Trends for Malewa River Catchment, Naivasha, Kenya. J Civ Constr Environ Eng. 2021;6(1):1-8. doi: 10.11648/j.jccee.20210601.11

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  • @article{10.11648/j.jccee.20210601.11,
      author = {Elizabeth Wambui Nyokabi and Raphael Muli Wambua and Romulus Okoth Okwany},
      title = {Assessment of Rainfall, Streamflow and Reservoir Level Trends for Malewa River Catchment, Naivasha, Kenya},
      journal = {Journal of Civil, Construction and Environmental Engineering},
      volume = {6},
      number = {1},
      pages = {1-8},
      doi = {10.11648/j.jccee.20210601.11},
      url = {https://doi.org/10.11648/j.jccee.20210601.11},
      eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.jccee.20210601.11},
      abstract = {Appropriate water quality and quantity are critical problem greatly affecting significant proportion of the population particularly those living in semi-arid and arid areas. Rainfall characteristics, streamflow and reservoir levels are some of the key hydro-meteorological variables within a catchment in the determination of sufficiency of water quantity. Lake Naivasha reservoir level continues to be hit by anthropogenic stressors such as loss of wetlands, water abstraction and eutrophication. Also there has been a lot of fluctuation in flow discharge of Malewa River over the years where the tributaries (Turasha and Karati streams) usually dries up during dry season. This paper presents the results of a research to assess the time series trends of rainfall, streamflow and lake basin levels data in the catchment from 1980-2018 using Mann-Kendall trend test to assess water quantity status. Monthly stream flow, rainfall and reservoir level data in the catchment were obtained from Water Resources Management Authority (WRMA) and Kenya Meteorological Department (KMD) for the years 1980-2018. Non-parametric Mann-Kendall rank statistics test was used to examine the trend components of hydro-meteorological variables. The P-values were used to test whether the null hypotheses were statistically significant (α<0.05) at a 5% level of significance. Rainfall values had an increasing trend from 2011 onwards but not statistically significant while annual streamflow values had no trend as P-value showed weak evidences to rejected the null hypothesis. Reservoir level had an upward trend in years 1981, 2001, 2003, 2012 and 2018 while downward trends in 1980, 1982, 1984, 1986, 1987, 2000, 2004, 2008 and 2014. From 2010 onwards, in monthly data, there have been upward water levels in the lake as shown by the trend. These show that the hydro-meteorological indicators in the catchment are independently trending, therefore some other factors such as land cover changes or climate changes were adversely affecting the hydrological cycle. These findings are helpful for planning and management in water resource systems such as forecasting water distribution and mitigate flood and drought.},
     year = {2021}
    }
    

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  • TY  - JOUR
    T1  - Assessment of Rainfall, Streamflow and Reservoir Level Trends for Malewa River Catchment, Naivasha, Kenya
    AU  - Elizabeth Wambui Nyokabi
    AU  - Raphael Muli Wambua
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    DO  - 10.11648/j.jccee.20210601.11
    T2  - Journal of Civil, Construction and Environmental Engineering
    JF  - Journal of Civil, Construction and Environmental Engineering
    JO  - Journal of Civil, Construction and Environmental Engineering
    SP  - 1
    EP  - 8
    PB  - Science Publishing Group
    SN  - 2637-3890
    UR  - https://doi.org/10.11648/j.jccee.20210601.11
    AB  - Appropriate water quality and quantity are critical problem greatly affecting significant proportion of the population particularly those living in semi-arid and arid areas. Rainfall characteristics, streamflow and reservoir levels are some of the key hydro-meteorological variables within a catchment in the determination of sufficiency of water quantity. Lake Naivasha reservoir level continues to be hit by anthropogenic stressors such as loss of wetlands, water abstraction and eutrophication. Also there has been a lot of fluctuation in flow discharge of Malewa River over the years where the tributaries (Turasha and Karati streams) usually dries up during dry season. This paper presents the results of a research to assess the time series trends of rainfall, streamflow and lake basin levels data in the catchment from 1980-2018 using Mann-Kendall trend test to assess water quantity status. Monthly stream flow, rainfall and reservoir level data in the catchment were obtained from Water Resources Management Authority (WRMA) and Kenya Meteorological Department (KMD) for the years 1980-2018. Non-parametric Mann-Kendall rank statistics test was used to examine the trend components of hydro-meteorological variables. The P-values were used to test whether the null hypotheses were statistically significant (α<0.05) at a 5% level of significance. Rainfall values had an increasing trend from 2011 onwards but not statistically significant while annual streamflow values had no trend as P-value showed weak evidences to rejected the null hypothesis. Reservoir level had an upward trend in years 1981, 2001, 2003, 2012 and 2018 while downward trends in 1980, 1982, 1984, 1986, 1987, 2000, 2004, 2008 and 2014. From 2010 onwards, in monthly data, there have been upward water levels in the lake as shown by the trend. These show that the hydro-meteorological indicators in the catchment are independently trending, therefore some other factors such as land cover changes or climate changes were adversely affecting the hydrological cycle. These findings are helpful for planning and management in water resource systems such as forecasting water distribution and mitigate flood and drought.
    VL  - 6
    IS  - 1
    ER  - 

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Author Information
  • Department of Agricultural Engineering, Egerton University, Nakuru, Kenya

  • Department of Agricultural Engineering, Egerton University, Nakuru, Kenya

  • Department of Agricultural Engineering, Egerton University, Nakuru, Kenya

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