Portal de Periódicos da CAPES

Characterization of Temporal Changes in Rainfall, Temperature, Flooding Hazard and Dry Spells over Zambia

2013; Volume: 1; Issue: 4 Linguagem: Inglês

10.13189/ujar.2013.010403

2332-2284

Lydia M. Chabala, Elias Kuntashula, Peter Kaluba,

Meteorological Phenomena and Simulations

Zambian rural communities are vulnerable to climate change because most farmers depend on rainfed agriculture.While efforts on adaptation are being spearheaded, information on the extent of climatic shifts and occurrence of extreme climatic events is limited.Therefore, a study was undertaken to assess changes in climatic variables of rainfall and temperature in Zambia's Agro-ecological zones.The objective of the study was to assess the extent of change in rainfall and temperature and to ascertain the occurrence pattern of extreme climatic events.Daily climatic data records were obtained from the Meteorological department in Zambia.Time series plots were prepared for trend detection in the inter-annual mean rainfall and temperature.A five year moving average was used to obtain the regression equations.Floods were defined to extremes greater than 40 mm in a day and to obtain their return period (T) in year, the cumulative probabilities, F, was transformed by using T=1/(1-F) or T = 100/(100-P) for percentages.A distribution free approach was fitted for estimation of return periods of dry spells in cases where rainfall totals may be zero.Results among the five stations (Choma, Petauke, Mpika, Serenje and Chipepo) considered, indicated that mean temperatures had an increasing trend which was statistically significant only for Choma district.Rainfall trends were variable with some stations (Mpika and Chipepo) showing increasing trends while others (Petauke and Serenje) showing decreasing trends.Floods were frequent in all stations analysed from January to March rather than October to November.Dry spell of 4 days duration were much more frequent than those of 7 and 10 days.Choma was found to be the most susceptible to dry spells while Mpika was the least affected.The study further revealed that the optimal planting widow was the last week of November up to the first week of December for rainfed crop production.