Monthly and Seasonal Rainfall Concentrations and Predictability in Tanzania

Authors

  • Pasvolo Mwinuka
  • Christian Uiso
  • Ladslaus Chang ' a
  • Mwingereza Kumwenda

Abstract

This study aimed at determining the monthly and seasonal rainfall concentration, predictability and the changes in rainfall seasons in Tanzania. Rainfall predictability was determined using Colwell ' s indices, Rainfall Concentration Index (RCI) and Coefficient of Variation (CV). Results showed that rainfall in December €“February (DJF), January €“March (JFM) and February €“April (FMA) has predictability due to constancy of 60%, RCI ‰¤ 9 and CV < 0.4 in Lake zone, Central zone, Southern Coast zone, Western and Southern Highlands zone. Rainfall in October to December (OND) was reliable in the Island zone, North-Eastern highlands zone and Northern coast zone with an average predictability due to constancy of 65%. In the Lake zone, all seasons (DJF, JFM, FMA, MAM, OND and DJFMAM) had uniform rainfall distribution (RCI = 8.7, CV = 0.35) and predictability due to constancy of 80% which leads to the conclusion that Lake Zone has unimodal rainfall distribution. Rainfall predictability in Tanzania has a West-East gradient. The western zones had an average predictability due to constancy of 68%. In general, rainfall in Tanzania is observed to be highly variable; only 20% of the predictability is concerned with reliability in the rainfall occurrence within the seasons and 80% is due to seasonality.

Keywords: Rainfall concentration index; predictability; coefficient of variation; seasonality; constancy.

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Published

2021-02-15

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Section

Articles