Analysis of Rainfall Trends and Extremes in the Minor Season of Ghana Mohammed Braimah, Vincent A
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Analysis of Rainfall Trends and Extremes in the Minor Season of Ghana Mohammed Braimah, Vincent A. Antwi, Maureen Ahiataku, Samuel O. Ansah, Frederick Otu-Larbi, Bashiru Yahaya Ghana Meteorological Agency Email: [email protected] , Phone: +233540354010 Introduction Results Discussion Table 1: Mann Kendall Trend Analysis of Minor Table 2: Mann Kendall Trend Analysis of Minor 14 out of 16 stations studied show non Conventionally, extreme rainfall events Seasonal Number of Rainy Days Seasonal Total Rainfall Trend h p z Tau s var_s S_slope Trend h p z Tau s var_s S_slope significant increase in rainfall amount usually occurred around April-July which Accra no trend False 0.1200 1.5700 0.18 126 6326 1.78 Accra no trend False 0.1368 1.4870 0.1692 119.0 6291.6 0.148 8 out of 16 stations show significant trend doubles as the major rainfall season of Ada no trend False 0.0890 1.6973 0.1930 136.0 6326.0 2.5166 Ada increasingTrue 0.0040 2.8760 0.3257 229.0 6281.6 0.333 of increasing total number of rainy days Ghana. On the contrary, the electronic and Tema no trend False 0.1021 1.6340 0.1860 131.0 6327.0 1.866 Tema increasingTrue 0.00776 2.6620 0.3015 212.0 6281.3 0.2222 The only 2 stations with increasing trends of print media in Ghana is flooded by rising Saltpond no trend False 0.2400 1.1800 0.1400 95.0 6327 1.9500 Saltpond no trend False 0.16079 1.4020 0.1593 112.0 6264.6 0.1333 rainfall are in the middle sector concerns of increasing rainfall cases and Takoradi no trend False 0.1820 1.3320 0.1520 131.0 6327.0 2.0829 Takoradi no trend False 0.1900 1.3104 0.14935 105.0 6298.33 0.1666 Axim no trend False 0.0600 1.9100 0.2200 153.0 6327 3.4100 In Fig. 2, east coast and transition zone its related events between September and Axim increasingTrue 0.0046 2.8270 0.3200 225.0 6278.3 0.3333 Koforidua no trend False 0.6300 0.4800 0.0600 39.0 6327 0.4000 from 2014 to 2018, experienced mostly November. This study seeks to Koforidua increasingTrue 0.0450 2.0000 0.2270 160.0 6295.33 0.2000 below average rainfall except Accra Provide more insights into the minor Abetifi no trend False 0.52789 0.6312 0.0725 51.0 6274.3 0.0625 Abetifi no trend False 0.0970 1.6590 0.1890 133.0 6327.0 2.4280 Ho no trend False 0.2570 1.1314 0.1294 91.0 6327.0 1.8388 The west coast and the middle sector show season of Ghana Ho no trend False 0.7430 -0.3278 -0.0384 -27.0 6290.3 0.000 Akim Oda increasingTrue 0.0047 2.8249 0.3200 225.0 6287.6 0.2500 Akim Oda increasing True 0.0221 2.2880 0.2600 183.0 6327.0 4.00000 positive rainfall anomalies Data and Methods Akuse no trend False 0.8598 0.1765 0.02133 15.0 6286.33 0.0000 Akuse no trend False 0.5290 -0.6285 -0.0725 -51.0 6327.0 -1.0599 Annual scale anomalies(Fig. 3) show mostly Sefwi BekwaiincreasingTrue 0.0015 3.1660 0.3584 252.0 6284.6 0.3300 Sefwi Bekwai no trend False 0.1070 1.6090 0.1830 129.0 6327.0 2.8330 rainfall deficits over southern Ghana in Kumasi increasingTrue 0.0077 2.6630 0.3015 212.0 6276.66 0.2307 Kumasi increasing True 0.0200 2.3400 0.2700 187.0 6327.0 4.4100 2014 Sunyani no trend False 0.6200 0.5000 0.0600 41.0 6327 0.9000 Sunyani no trend False 1.0000 0.0000 0.0000 0.0 6278.0 0.0000 Both annual and minor season total rainfall Wenchi no trend False 0.1465 1.4519 1.4519 116.0 6273.33 0.1538 Wenchi no trend False 0.4060 0.8297 0.1830 67.0 6327.0 0.8750 amounts over the east coast experienced Kete Krachi increasingTrue 0.0450 2.00395 0.2275 160.0 6295.33 0.2000 Kete Krachi no trend False 0.6328 0.4777 0.0554 39.0 6327.0 0.39565 negative anomalies except for 2018 Conclusion Rainfall amounts show mostly non Figure 1: Map showing rainfall stations over significant increase in rainfall but there is southern Ghana a significant trend of rainy days from 1981 Data: Daily Rainfall Amount (1981-2018) to 2018, at a significant level of 95%. Rainfall Groups: East Coast (Accra, Tema, Positive extremes are highest over Ada), West Coast (Takoradi, Saltpond , Axim), stations in the middle sector and west Middle Sector (Koforidua, Akim Oda, Abetifi, coast, but negative extremes are found Ho, Akuse, Kumasi, Sefwi Bekwai) and over the east coast and transition zone. Transition Zone (Kete Krachi, Wenchi, Future works are recommended to focus Sunyani) on vegetative enhanced parameters such Approach: Regression Analysis, Mann- Fig. 2: Rainfall Anomalies in Minor Season (a) East as evapotranspiration on rainfall amount Kendall Trend test, and standardized anomaly Fig. 3: Annual Rainfall Anomalies over and frequency Coast (b) West Coast (c, d ) Middle Sector (e) southern Ghana analysis Transition Zone RESEARCH POSTER PRESENTATION DESIGN © 2019 www.PosterPresentations.com.