Title: Rainfall Trend Analysis by Mann-Kendall Test and Sen's Slope Estimator: A Case Study Kano Plains, River Nyando Basin, Kenya.
Authors: George Gor
Dr. Mary Makokha
Professor Joy Obando
Volume: 7
Issue: 12
Pages: 113-126
Publication Date: 2023/12/28
Abstract:
Rainfall variability has been a concern for the last few decades globally, regionally and nationally. Efficient planning and designing of required water resources will depend on the rainfall trend analysis of that area. The present study sought to determine rainfall variability within Kano plains in Kisumu County, Kenya. In this present study the rainfall variability was investigated using Mann-Kendall Test for coefficient of variance (CV%) and statistical significance of trends. Daily rainfall data for 40 years (1980-2020) for Ahero Irrigation and Koru Bible Centre stations has been used to analysis Monthly, Seasonal and Annual rainfall trends. The seasonal analysis was done depending on the meteorological seasons of Kano Plains, JF (short dry), OND (short rains), JJAS (long dry), MAM (long rains). The study revealed relationship between the two stations in their monthly rainfall trend. This was evidence on their strong significant increasing correlation coefficient (0.697) and ? = 0.02, p(2-tailed) < 0.05 with a correlation of determinant of 48.6%. Secondly, the study revealed that, there was maximum mean monthly rainfall during MAM (482.5 mm and 526.7 mm) and minimum mean monthly in the JF (164.5mm and 160.6 mm) for Ahero Irrigation and Koru Bible Centre stations respectively. Thirdly, based on the analysis of correlation of variance, MAM (28.1% and 28.2%) rainfall is more predictable than the other seasons for Ahero Irrigation and Koru Bible Centre respectively. Finally, increasing insignificant annual rainfall trend for Ahero Irrigation with correlation coefficient of 0.193 and ? = 0.076, p (2-tailed) > 0.05. However, Koru Bible Centre showed a decreasing significant rainfall trend with correlation coefficient of -0.406 and ? = 0.000, p (2-tailed) < 0.05. Therefore, the study concluded that there was monotonic rainfall trend in all the seasons (monthly, seasonal and annual) in Kano Plains. Furthermore, the study recommends the necessity to formulate adaptation strategies to mitigate impacts of rainfall variability to preserve aquifers to become more productive especially during lean seasons within Kano Plains area. This electronic document is a "live" template and already defines the components of your paper [title, text, heads, etc.] in its style sheet.