Analysis of rainfall characteristics in Tanzania for climate change signals

Abstract

Tanzania as many other countries in Africa depends on rain water for various economic activities in order to achieve its development. The global climate change has not isolated Tanzania, the rainfall climatology of the country has some changes which need to be taken into account while planning for economic activities such as hydro power generation, civil and structural engineering, mining, Agriculture which is the back-borne of the country as it is the main source of employment, foreign currency and revenue. This study aims at aims examining the rainfall characteristics over Tanzania in order to determine the climate change signals in rainfall characteristics in particular. The daily, monthly and seasonal rainfall datasets from all the eleven zones in Tanzania covering a period of 48 years from 1961 to 2008 were used. Tanzania meteorological agency is the source of data used. Arithmetic method was used to estimate the missing data for Loliondo the only station which had missing data. The single line mass curve method was used to test homogeneity of the data for the stations selected to represent each of the eleven zones, results from the mass curve showed all the data from all the seven zones were homogeneous. During analysis, time series and trend methods were used. The eleven zones used in this research project were adopted from the ones used by the Tanzania Meteorological Agency. This study revealed that all the zones have some changes in their rainfall characteristics as the amounts of seasonal rainfall were found to show decreasing trends in some stations and increasing trends in the others. The time series for the accumulated seasonal rainfall in pentads showed delays in the onsets and cessations while other zones were found to experience delay of onsets and earlier cessations implying the seasons are becoming short. Rainfall characteristics in Tanzania are changing differently in different parts over the country. The people in the country especially those who are stakeholders of the meteorological services in particular rainfall must be empowered with updates in changes of rainfall climatology. Agriculture as a long time and term back-born of the country should be adequately performed along the current changes in the rainfall characteristics so as to make it sustainable and profitable and therefore avoiding the demerits which normally arise from poor harvests and hence control for the food security