Abstract:
A methodology has been applied to investigate
the spatial variability and trends existent in a mid-twentieth
century climatic time series (for the period 1943–1977)
recorded by 58 climatic stations in the Albert–Victoria water
management area in Uganda. Data were subjected to quality
checks before further processing. In the present work, temporal
trends were analyzed using Mann–Kendall and linear
regression methods. Heterogeneity of monthly rainfall was
investigated using the precipitation concentration index
(PCI). Results revealed that 53 % of stations have positive
trends where 25 % are statistically significant and 45 % of
stations have negative trends with 23 % being statistically
significant. Very strong trends at 99 % significance level
were revealed at 12 stations. Positive trends in January,
February, and November at 40 stations were observed. The
highest rainfall was recorded in April, while January, June,
and July had the lowest rainfall. Spatial analysis results
showed that stations close to Lake Victoria recorded high
amounts of rainfall. Average annual coefficient of variability
was 19 %, signifying low variability. Rainfall distribution is
bimodal with maximums experienced in March–April–May
and September–October–November seasons of the year.
Analysis also revealed that PCI values showed a moderate
to seasonal rainfall distribution. Spectral analysis of the time components reveals the existence of a major period around
3, 6, and 10 years. The 6- and 10-year period is a characteristic
of September–October–November, March–April–
May, and annual time series.
