Reference Basic Wind Speed for Selected Towns/Cities in Ethiopia

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Date

2016-07

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Addis Ababa University

Abstract

A data on three hourly wind speeds, from 18 meteorological centre of Ethiopia Meteorological Department, have been collected. The daily gust wind data have been processed for annual maximum wind speed in m/sec for each site. This research paper presents an attempt made towards preparing a wind zone map based on observed wind speeds at each weather station in the country. The data used were annual maximum 180 minute average wind speeds recorded at about 10 m above ground level. These 180 minute average wind speeds were changed to 10 minute mean wind speeds by the factor 1.32. Several probability distributions were tested for suitability and Extreme Value Type I (log Gumbel) distribution was found to be the best fitting distribution for the maximum wind speeds at Arba Minch and Hawassa. Log Pearson distribution was found to be the best fitting distribution for the maximum wind speeds at Dire Dawa and Kombolcha. Log Normal distribution was found to be the best fitting distribution for the maximum wind speeds at Addis Ababa, Bahir Dar, Debre Markos, Debre Zeit, Gode, Gondar, Gore, Jimma, Kibre Mengist, Mekelle, Metehara, Negelle, Nekemte and Robe. An attempt to demarcate wind speeds for the selected stations was prepared using the 5, 10, 15, 20, 25, 30, 50, 100, 200, 500 and 1000 year return period wind speeds resulted from the best fitting probability distributions. This map was based on basic wind speeds calculated from actual annual maximum records of each station. The basic wind speed values ranged from 30m/sec to 45m/sec. Keyword: Wind speed, Fitting distribution method, Return period

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Keywords

Wind speed, Fitting distribution method, Return period

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