Interannual variability in rainy season characteristics over the Limpopo region of southern Africa

Abstract

This study focuses on the interannual variability of dry spell frequencies, dry and wet spell characteristics and onset dates of the austral summer rainy season over the Limpopo region (22-25°S, 27-32°E) of northern South Africa. These characteristics of the rainy season are of considerable interest to farmers, water resource managers and other user groups. The Limpopo region supports a large rural population dependent on rain-fed agriculture as well as significant biodiversity, particularly in the Kruger National/Limpopo Transfrontier Park. It is also a region prone to devastating floods and droughts. Evidence is presented that summer dry spell frequency and onset date are related to ENSO via changes in regional circulation. Niño 3.4 sea surface temperature (SST) anomalies appear to show a robust relationship with dry spell frequency during the 1979-2002 period analysed. Anomalies in onset date of the rainy season during 1979-2002 appear to be inversely related to Niño 3.4 SST, with the relationship strengthening after 1986. These results suggest that there may be some predictability in these parameters, particularly in dry spell frequency during austral summer, based on existing skill in predicting tropical Pacific SST.

Stochastic simulation of rainfall in the semi‐arid Limpopo basin, Botswana

“…Neither temperature nor pressure was significant in the amounts model. Although the ENSO indices were expected to be important based on the literature (Richard et al, 2000;Mulenga et al, 2003;Reason et al, 2005;Manatsa et al, 2008), none of these indices were within the eight most statistically significant external predictors.…”

“…Annual rainfall in the study area varies from year to year. This variability may be partly associated with the El Niño-Southern Oscillation (ENSO) phases that are often linked with droughts and seasonal rainfall variability over southern Africa (Reason et al, 2005). However, recent studies suggest that ENSO may be poorly associated with rainfall in some parts of southern Africa (Manatsa et al, 2008).…”

Drought tolerant maize for farmer adaptation to drought in sub-Saharan Africa: Determinants of adoption in eastern and southern Africa

“…The onset of the rainy season is crucial to the timing of rainfed crops: if a farmer plants too early, soil moisture will be insufficient for seed germination; if a farmer plants too late, intense rain might wash seed away (Reason et al 2005). Farmers in several SSA countries reported they shift crop planting dates in response to year-to-year variability in rainy season onset (Fosu-Mensah et al 2012;Bryan et al 2013;Sofoluwe et al 2011;Bele et al 2014).…”

Climate Change Impacts on Water Availability and Use in the Limpopo River Basin

“…Precipitation is highly seasonal and unevenly distributed spatially, with about 95 percent of precipitation occurring between October and April [8]. Precipitation also varies significantly from year to year [10]. These precipitation characteristics limit crop production because annual precipitation mainly occurs during a short summer rain season with high inter-annual variations.…”