Dry spells and probability of rainfall occurrence for Lake Kyoga Basin in Uganda, East Africa

Ojara, Moses; Li, Yunsheng; Aribo, Lawrence; Namumbya, Silvia; Uddin, Md. Jalal

doi:10.1007/s11069-019-03822-x

Cited by 31 publications

(28 citation statements)

References 77 publications

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“…On the linear trend analysis, other existing studies equally noted a declining trend in rainfall during the local wet season of MAM (Funk et al 2005;Lyon and Dewitt 2012;Liebmann et al 2014). The season mentioned above is considered as the main growing season for agricultural activities that support 70% of the local economy (McSweeney et al 2010;Ojara et al 2020). This decrease would influence food security and livelihoods of the people.…”

Section: Spatiotemporal Variability Of Annual and Seasonal Rainfallmentioning

confidence: 93%

“…The rainfall climatology is mostly influenced by the seasonal oscillation of Inter-Tropical Convergence Zone (ITCZ) (Nicholson 2018), monsoon winds and sub tropical anticyclones (Basalirwa 1995, Nicholson et al 2017. Thus, most parts of the study area receive bimodal rainfall patterns with 'long rains' occurring in MAM whilst 'short rains' witnessed in September to November (SON) (Nsubuga et al 2014;Ojara et al 2020). This, however, results in a uni-modal pattern as the distance from the equator increases steadily.…”

Section: Study Areamentioning

confidence: 98%

See 1 more Smart Citation

Assessing current and future spatiotemporal precipitation variability and trends over Uganda, East Africa, based on CHIRPS and regional climate model datasets

Ngoma

Wang

Ojara

et al. 2021

Meteorol Atmos Phys

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The lack of reliable rainfall projection records remains a major challenge to Uganda. In the advent of extreme wetness or drought events, reliable rainfall estimates for local planning and adaptation are essential. The present study used two main datasets to conduct a historical analysis from 1981 to 2019, coupled with future projections under representative concentration pathway (RCP 8.5) for the period 2020-2050. Historical analysis revealed bimodal annual rainfall pattern for March-May (MAM) and September-November (SON) gradients representing heavier to lighter rainfall events respectively over the study area. Investigation of recent trends in rainfall patterns revealed an upward trend from 2010 onwards in annual and seasonal rainfall. Moreover, results for future projections show wet conditions are projected to occur over the study area between the months of April/May and October. Contrarily, March is likely to experience a reduction in wet conditions. Mann-Kendall test employed to make future projections of rainfall depicted decreasing patterns during MAM season whilst increasing tendencies with strong shift was highlighted for SON season over the study region. Meanwhile, annual projections indicate huge variations with linear trends showing a marginal increase as compared to historical trends. Findings would serve as baseline print to propel further studies

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Section: Spatiotemporal Variability Of Annual and Seasonal Rainfallmentioning

confidence: 93%

Section: Study Areamentioning

confidence: 98%

Assessing current and future spatiotemporal precipitation variability and trends over Uganda, East Africa, based on CHIRPS and regional climate model datasets

Ngoma

Wang

Ojara

et al. 2021

Meteorol Atmos Phys

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show abstract

“…Sen [59] developed the non-parametric procedure for estimating the magnitude of a trend in the time series given by Sen's slope test (Q 2 ) [55,60]. The test gives a more robust estimation of the trend, especially when the trend cannot be estimated by other statistical approaches like Kendall's test statistics or regression [60]. The positive results of Q 2 in the number of dry dekads and the maximum length of consecutive dry spell dekads represent an increasing trend, while the negative values represent decreasing trends over a given time.…”

Section: Sen's Slope Estimatormentioning

confidence: 99%

Spatial and Temporal Analysis of Dry and Wet Spells in Upper Awash River Basin, Ethiopia

Adane

Hirpa

Lim

et al. 2020

Water

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This study aimed to analyze the probability of the occurrence of dry/wet spell rainfall using the Markov chain model in the Upper Awash River Basin, Ethiopia. The rainfall analysis was conducted in the short rainy (Belg) and long rainy (Kiremt) seasons on a dekadal (10–day) scale over a 30-year period. In the Belg season, continuous, three-dekad dry spells were prevalent at all stations. Persistent dry spells might result in meteorological, hydrological, and socio-economic drought (in that order) and merge with the Kiremt season. The consecutive wet dekads of the Kiremt season indicate a higher probability of wet dekads at all stations, except Metehara. This station experienced a short duration (dekads 20–23) of wet spells, in which precipitation is more than 50% likely. Nevertheless, surplus rainwater may be recorded at Debrezeit and Wonji only in the Kiremt season because of a higher probability of wet spells in most dekads (dekads 19–24). At these stations, rainfall can be harvested for better water management practices to supply irrigation during the dry season, to conserve moisture, and to reduce erosion. This reduces the vulnerability of the farmers around the river basin, particularly in areas where dry spell dekads are dominant.

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“…Extreme weather events in form of droughts and floods have been reported over the region by previous studies (Ogwang et al, 2015;Nicholson, 2017;Ojara et al, 2020). These are as a result of below normal, above normal or changes in onset, frequency, duration, and intensity of rains in different seasons.…”

Section: Introductionmentioning

confidence: 91%

Mechanisms associated with September to November (SON) rainfall over Uganda during the recent decades

Ngoma¹,

Wang²,

Ayugi³

et al. 2021

Geographica Pannonica

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This study revisits teleconnections associated with the anomalous events of September to November (SON) rainfall over Uganda during 1981-2019, owing to the recent intensification of extreme events. Empirical Orthogonal Function (EOF), Composite and Correlation analysis are employed to examine the variability of SON rainfall over the study domain and associated circulations anomalies. The first EOF mode (dominant mode) displays a positive monopole pattern and explains 67.2% of the variance. The results revealed that SON rainfall is largely influenced by a Walker circulation mode over the Indian Ocean, whereby, wet events are associated with an ascending limb of the Walker circulation on the western part of the Indian Ocean characterized by convergence at low levels and divergence at upper level. The study showed that SON rainfall is positively (negatively) correlated with Indian Ocean (Atlantic Ocean) sea surface temperatures (SST). Furthermore, Indian Ocean Dipole (IOD) events have impact on SON rainfall with strong positive correlation, whereas Southern Oscillation Index (SOI) revealed negative correlation. The results also reveal that there is a lag in ENSO and IOD episodes during wet/dry events over the region. ENSO and IOD also tend to extend the rainfall season of SON and thus study of extreme events may not be well captured by studies focusing on SON. Future studies might consider the season of October to December or December to February. These phenomena need to be closely monitored and considered when making seasonal forecasts.

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Dry spells and probability of rainfall occurrence for Lake Kyoga Basin in Uganda, East Africa

Cited by 31 publications

References 77 publications

Assessing current and future spatiotemporal precipitation variability and trends over Uganda, East Africa, based on CHIRPS and regional climate model datasets

Assessing current and future spatiotemporal precipitation variability and trends over Uganda, East Africa, based on CHIRPS and regional climate model datasets

Spatial and Temporal Analysis of Dry and Wet Spells in Upper Awash River Basin, Ethiopia

Mechanisms associated with September to November (SON) rainfall over Uganda during the recent decades

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