Trends and spatial distribution of annual and seasonal rainfall in Ethiopia

Authors

  • Wing H. Cheung,

    Corresponding author
    1. UNEP Division of Early Warning and Assessment-North America, National Centre for Earth Resources Observation and Science, Sioux Falls, SD 57198, USA
    • UNEP Division of Early Warning and Assessment-North America, National Centre for Earth Resources Observation and Science, Sioux Falls, SD 57198, USA.
    Search for more papers by this author
  • Gabriel B. Senay,

    Corresponding author
    1. SAIC, contractor to US Geological Survey (USGS) Center for Earth Resources Observation and Science, Sioux Falls, SD. Work performed under USGS contract 03CRCN0001, USA
    • SAIC, contractor to US Geological Survey (USGS) Centre for Earth Resources Observation and Science, Sioux Falls, SD. Work performed under USGS contract 03CRCN0001, USA.
    Search for more papers by this author
  • Ashbindu Singh

    1. UNEP Division of Early Warning and Assessment-North America, National Centre for Earth Resources Observation and Science, Sioux Falls, SD 57198, USA
    Search for more papers by this author

Abstract

As a country whose economy is heavily dependent on low-productivity rainfed agriculture, rainfall trends are often cited as one of the more important factors in explaining various socio-economic problems such as food insecurity. Therefore, in order to help policymakers and developers make more informed decisions, this study investigated the temporal dynamics of rainfall and its spatial distribution within Ethiopia. Changes in rainfall were examined using data from 134 stations in 13 watersheds between 1960 and 2002. The variability and trends in seasonal and annual rainfall were analysed at the watershed scale with data (1) from all available years, and (2) excluding years that lacked observations from at least 25% of the gauges. Similar analyses were also performed at the gauge, regional, and national levels. By regressing annual watershed rainfall on time, results from the one-sample t-test show no significant changes in rainfall for any of the watersheds examined. However, in our regressions of seasonal rainfall averages against time, we found a significant decline in June to September rainfall (i.e. Kiremt) for the Baro-Akobo, Omo-Ghibe, Rift Valley, and Southern Blue Nile watersheds located in the southwestern and central parts of Ethiopia. While the gauge level analysis showed that certain gauge stations experienced recent changes in rainfall, these trends are not necessarily reflected at the watershed or regional levels. Copyright © 2008 Royal Meteorological Society

Ancillary