Civil Engineering / İnşaat Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/13
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Article Citation - WoS: 33Citation - Scopus: 37Trend Analysis of Temperature and Precipitation in Trarza Region of Mauritania(IWA Publishing, 2019) Yacoub, Ely; Tayfur, GökmenTrend analysis of annual temperature and precipitation time series data collected from three stations (Boutilimit (station 1), Nouakchott (station 2) and Rosso (station 3)) has been used to detect the impacts of climate change on water resources in Trarza region, Mauritania. The Mann-Kendall, the Spearman's rho, and the Sen trend test were used for the trend identification. Pettitt's test was used to detect the change point of the series while the Theil-Sen approach was used to estimate the magnitude of the slope in the series. For precipitation, two stations (1 and 3) indicated statistically significant increase in trends. In the case of temperature, almost all the stations show statistically significant increasing trends in the maximum, minimum, and average temperatures. The magnitude of precipitation detected by the Theil-Sen test for stations 1 and 3, respectively, was found to be at the rate of 2.93 and 3.35 mm/year at 5% significance level. The magnitude trend of temperature detected by the Theil-Sen approach was found to be at the rate of 0.2-0.4 degrees C per decade for almost all the stations. The change points of temperature trends detected by Pettitt test are found to be in the same year (1995) for all the stations.Article Citation - WoS: 32Citation - Scopus: 34Spatial and Temporal of Variation of Meteorological Drought and Precipitation Trend Analysis Over Whole Mauritania(Elsevier, 2020) Yacoub, Ely; Tayfur, GökmenUsing monthly precipitation data from 15 stations, well spread over whole Mauritania, and recorded for a long period of time (1919-2016) of almost 100 years, a classification of drought is performed, based on its intensity and duration. For this purpose, the gamma-Standardized Precipitation Index (gamma-SPI) is used to detect drought events (drought frequency, duration and intensity). The Mann-Kendall Test (MK test) is employed for the trend analysis of the precipitation data at all stations and the Thiel-Sen Approach is used to calculate the magnitude of the slopes of the trends. The drought analysis results show that there were severe and extreme drought conditions seen all over the country, especially in 1970s and 1980s. This serious case seems to be emerging in early 2010s. The drought conditions in recent years seems to be more pronounced in the central and southern regions of the country. The trend analysis results reveal that there is no depletion observed in precipitation at the northern region. The total deficit in precipitation is about 100 mm or less during almost 100 year period at the western region. However, the results show that there is pronounced decrease in precipitation at the southern region, reaching to almost a total of 300 mm deficit in nearly 100-year period.Article Citation - WoS: 45Citation - Scopus: 51Evaluation and Assessment of Meteorological Drought by Different Methods in Trarza Region, Mauritania(Springer Verlag, 2017) Yacoub, Ely; Tayfur, GökmenDrought Indexes (DIs) are commonly used for assessing the effect of drought such as the duration and severity. In this study, long term precipitation records (monthly recorded for 44 years) in three stations (Boutilimit (station 1), Nouakchott (station 2), and Rosso (station 3)) are employed to investigate the drought characteristics in Trarza region in Mauritania. Six DI methods, namely normal Standardized Precipitation Index (normal-SPI), log normal Standardized Precipitation Index (log-SPI), Standardized Precipitation Index using Gamma distribution (Gamma-SPI), Percent of Normal (PN), the China-Z index (CZI), and Deciles are used for this purpose. The DI methods are based on 1-, 3-, 6-, and 12 month time periods. The results showed that DIs produce almost the same results for the Trarza region. The droughts are detected in the seventies and eighties more than the 1990s. Twelve drought years might be experienced in station 2 and six in stations 1 and 3 in every 44 years, according to reoccurrence probability of the gamma-SPI and log-SPI results. Stations 1 and 3 might experience fewer drought years than station 2, which is located right on the coast. In station 1, which is located inland, when the annual rainfall is less than 123 mm, it is likely that severe drought would occur. This is 63 mm/year for station 2 and 205 mm/year for station 3 which is located in the south west on the Senegal River. DI results indicate that the CZI and the gamma-SPI methods make similar predictions and the log-SPI makes extreme drought predictions for the monthly period for all the stations. For longer periods (3-, 6-, and 12 month period), for all the stations, the log-SPI and the gamma-SPI produce similar results, making severe drought predictions while the normal-SPI and the CZI methods predict more wet and fewer drought cases. The log-SPI, the gamma-SPI, PN and Deciles were able to capture the historical extreme and severe droughts observed in early 1970s and early 1980s.