Analysis of Spatio-temporal rainfall trends and rainfall variability in Botswana between 1958 and 2019

Abstract

Environments with a climatic characteristic of semi-aridity exhibit high rainfall variability, increasing significantly as the climate changes. In this study, rainfall concentration and Spatiotemporal trends in annual and seasonal (November to March) rainfall in Botswana were analyzed. The satellite data is obtained from the Southern African Science Service Centre for Climate Change and Adaptive Land Management and the Climate Toolbox. The Mann-Kendall trend test (MK), autocorrelation function (ACF), relative percentage change (RPC), precipitation concentration index (PCI), and Theil-Sen's slope estimator (β) methods were adopted for data analysis. The regions include Gaborone, Maun, Francistown, Serowe, Kasane, Tsabong, Ghanzi, and Pandamatenga. The results indicated that the magnitude of change of change of the significant downward trends in the annual rainfall was found to be -1.11 mm/year at Maun, -1.62 mm/year at Ghanzi, -0.33 mm/year at Pandamatenga, and -0.25 mm/year at Tsabong. The magnitude of change of change of the significant downward trends in the seasonal rainfall was between -0.60 mm/year at Pandamatenga and -0.19 mm/year at Tsabong. All these regions, except Ghanzi, experienced a downward trend in the rainfall distribution. This is owing to the synoptic characteristic of the below-average geopotential heights over Ghanzi. Which might exacerbate the formation of convective systems, leading to a positive rainfall trend at Ghanzi. The annual calculated PCI values are divided into three classes; PCI>10≤15, PCI>16≤20, and PCI>20. The Mann-Kendall analysis of the PCI values indicates that all the regions experienced a downward rainfall trend, implying that it is heading toward a uniform to a moderate distribution. There were distinct patterns that emerged from the Pandamatenga region, indicating a strongly irregular distribution. The regions of Kasane, Maun and Francistown, demonstrated moderate to an irregular distribution. For Gaborone and Francistown, results showed occurrences of a moderate to strongly irregular distribution.

City-Level Law and Action for Climate-Resilient Development in Southern Africa

“…160 This understandably has adverse implications for agriculture and the water sector, leading to food insecurity. 161 A recent study on spatio-temporal rainfall variability in Botswana confirmed a decrease in rainfall in Francistown 162 but, as in the case of Gaborone, Francistown has also been affected by disastrous flooding. 163 Botswana does not have climate change-specific local (city-level) laws and policies, as far as could be established.…”

“…154 As in the case of the cities in Zimbabwe and Namibia, droughts and water scarcity affect the agricultural sector and food security in the area. 155 Studies in 2014 indicated a decline in the capacity of the Gaborone Reservoir, which supplies water to the city, such that it was impossible at the time to pump out water. 156 Water scarcity has also historically led to water rationing in Gaborone, which left citizens without water for some days.…”

Review of the use of R Programming for Data Analysis in Botswana Research

“…[44] computed R/S analysis for the residual series obtained after filtering periodicities, showed that they have statistical properties close to the ordinary Brownian noise using Base R.A study by [45] used fluxes calculated using Base R to assess net atmospheric Methane (CH4) fluxes and controlling environmental factors in the Okavango Delta. [46]analysed rainfall concentration and spatio-temporal trends in annual and seasonal November to March rainfall in Botswana. The Precipitation Concentration Index (PCI), Mann-Kendall trend test, Theil-Sen's slope estimator (β), Autocorrelation Function (ACF) and relative percentage change (RPC) methods were adopted for data analysis were performed using Base R. [47]research determine trends in the annual maximum average rainfall for Botswana during the years 1901-2012.…”