RAINFALL VARIABILITY AND TREND ANALYSIS OF MULTIANNUAL . Southern African Monthly Rainfall Variability: An Analysis Based on Generalized Linear Models. (iii)The analysis of the map shown in Figure 3(c) for the 2002–2011 period of measurements clearly illustrates the predominance of rainy and very rainy years at most stations (25). Rep. 1108, 2013. A little more than 60% of rainfall accumulations recorded at various stations are considered as dry or very dry. The “RI” is calculated as follows: where is year value, is the series average, and is standard deviation. Indeed, the hydrological cycle acceleration under the influence of strong temperatures might lead to more rainfall and evaporation [4]. As regards Algeria, the situation seems similar because the 2008/2009 agricultural campaign was described as highly satisfactory and the cereal production recorded the following year (2009/2010) is a record of 61.2 million quintals that has never been equalled. A number of techniques have been developed for the variability and trend analysis of the rainfall time series. This return of rainfall over central Maghreb, should it be confirmed, could mean the end of several decades of recurrent droughts and announce a durable return to “the normal.” This assumption is supported by emphasizing the impact of different world climate oscillations (North Atlantic Oscillation; El Niño Southern Oscillation) for all the continents and particularly for the African continent [27, 48]. CV is calculated by the standard deviation divided by the mean annual of rainfall over the study period. rainfall variability from two other new reanalyses, the ECMWF Re-Analysis Interim (ERAI), and the Modern Era Retrospective-analysis for Research and Applications (MERRA), is also assessed. These investigations should integrate and quantify the role of terrigenous aerosols in the dynamics of local climate and show the importance of sea surface temperatures in regulating rainfall. Rainfall in Nigeria is subjected to wide variability both in time and space. Their results showed intra and inter-annual variability of rainfall and the annual, small, and main rainy seasons indicated a declining trend at a rate of 15.03, 1.93, and 13.12 mm per decade, respectively. studied the variability and time series trend analysis of rainfall and temperature in Woleka sub-basin, north-central Ethiopia. ONM, Office National de la Météorologie (Algeria): Direction de la Météorologie Nationale (Morocco): IMN, Institut de la Météorologie Nationale (Tunisia): International Journal of Atmospheric Sciences, https://www.ipcc.ch/pdf/assessment-report/ar5/wg1/WG1AR5_SummaryVolume_FINAL_FRENCH.pdf, http://www.ncdc.noaa.gov/sotc/global/2014/13, https://www.ipcc.ch/pdf/assessment-report/ar4/wg1/ar4-wg1-chapter11.pdf, http://www.fao.org/fileadmin/user_upload/rome2007/docs/Climate_Change_Adaptation_Water_Sector_NENA.pdf. We can see in Figure 5(a) that, since the 2000s, the percentage developed for dry and very dry years has been clearly in constant decline in all three countries. It reveals the importance of positive differences which indicate an increase of the former category in 83% of the stations. Author content. (2018). The values are relatively high for 1982 (−1.12), 1983 (−1.21), and 1986 (−0.93). The beginning of the period tends less to this oscillation (a sequence of three rainy years is noticeable from 1971 to 1973). This first processing is followed by a reordering procedure (permutations of columns) in order to get a ranking that allows the visualisation of a homogenous coloured structure (Bertin matrix) (Figure 2). The last period (2003–2013) is considered wet. Rainfall data from 77 stations were analysed to determine the mean annual and interdecadal rainfall variability and distribution in Ghana for the period 1981-2010. An annual data precipitation (cumulative rainfall over a calendar year) hierarchy in terms of limit values (Q1, Q2, Median, Q3, and Q4) is done for all stations and for the entire series (Table 1). It is a period of severe drought which marks a large part of the Moroccan territory. [21] analyzed future climate conditions for the Mediterranean region based on 16 Global Climate Models. Reduced centered deviations of annual rainfall accumulations recorded in central Maghreb (mobile average calculated for 35 weather stations in 1970–2011). These rains ensured a record cereal production of 80 million quintals (for 2009/2010). The last period of this precipitation series (2003–2013), in which 82% of the years have a positive regional index, is described as rainy. Understanding the decadal and/or annual variability and distributions of rainfall of a region is important and useful especially for agricultural activities. The method used for this study is the chronological graphic method of information processing (MGCTI) of “Bertin matrix” type. Find support for a specific problem on the support section of our website. Climate change is today acknowledged by a large part of the scientific community. 2 . Sign up here as a reviewer to help fast-track new submissions. The values are relatively high for 1982 (−1.12), 1983 (−1.21), and 1986 (−0.93). Despite this feature, and considering temperature rise, an increase in rainfall is likely to occur in certain region of the world favorable to such climate evolution. At the same time, the temperature trend continues to be rising (despite a slight cooling of values recorded during the last years). According to the results of various prediction of climatic models, both global and regional, a rise in temperatures and decrease in rainfall are expected [15–17]. ANOVA decomposes the variation into “systematic” and “random” components. A second stage starts in 1987 and finishes in 2002. Among the retained indices, relative humidity and El Niño accounted for the highest degree of explained variability. 2020. A recoding of values is made by means of a range of colours (the colour varying in terms of the annual cumulative rainfall position in relation to limit values). (iii)The last period (2003–2013) is considered wet. GIS maintains the spatial location of sampling points, and … This trend was confirmed for 2012/2013 because, with an average pluviometry of 450 mm, the excess rainfall on a national scale amounts to +20% as compared to a normal year [42]. Nouaceur, Z.; Murarescu, O. Rainfall Variability and Trend Analysis of Rainfall in West Africa (Senegal, Mauritania, Burkina Faso). Our analysis has several caveats. This graphical representation allows us to see the evolution of extreme rainfall for the two already discussed periods. The higher variability observed in the Indus basin varies from 12 to 87.1%, with a mean value … [19] lead to the same result with a 20% rainfall decline south of the Mediterranean Sea according to a climate warming scenario of +2°C. previous studies on rainfall variability in Northern Nigeria such as [12][11] [13] and [14] relied mainly on statistical analysis of rainfall variation in their asess- s ment of rainfall trend and drought. The first humid stage is noticeable from 1970 to 1979, followed by the great climatic drought which lasts almost a half a century and, finally, the rainfall return which can be noted as of 2003. This movement is governed by an overall moving of the meteorological equator and its low-pressure corridor (Intertropical Convergence Zone, ITCZ) towards the north, under the effect of the attraction of the Saharan thermal depressions and a greater vigor of the anticyclonic nuclei. The missing data were supplemented with information gathered from the NCDC “National Climatic Data Center” website (http://www.ncdc.noaa.gov/). Rainfall is a dynamic phenomenon, which changes over time and space. (iii)The regional index reaches, during this final year, one of the lowest values of the series, −1.41. This matrix is used to group the data that have similarities according to all the criteria studied. The processing of the trend of extreme years from 1970 to 2013 (the percentage of stations which recorded a rainy and very rainy year, dry and very dry year or a normal one) for the three countries confirms previous results. Chiara Ambrosino 1 , Richard E. Chandler 2 , and Martin C. Todd 3 View More View Less. A first wet period marks the precipitation series in Morocco (1970–1979) while, in the other two countries, from 1970 to 1986, no significant trend can be noted. According to Chidozie et al, rainfall variability increases from … Finally, Khomsi et al. The years belonging to the dry and very dry class totalize almost 55% for all stations. Mobile frequency averages of stations that recorded dry and very dry years (a), rainy and very rainy years (b), and normal years (c) (1970–2011 for Morocco and 1970–2013 for Algeria and Tunisia). In Tunisia, recent studies [31] show that annual precipitation trend is on the rise for 19 regions surveyed during 1977–2011. The second period is marked by a dry trend which lasts 16 years on this territory. (v)The stage covering the 1998–2001 period is marked by the return of drastic conditions. Complete analysis of rainfall events requires a study of both its spatial and temporal extents. Faced with such great changes that today affect the Maghreb region and given the complexity of spatial and temporal dimensions of the climatic signal, a more thorough research of causes and retroactions would allow for a better understanding of the mechanisms behind this new trend. Using ADDAPIX software, a spatial and temporal analysis is achieved. In 1980, a new drier climatic phase began and lasted until 2001. Variability analysis involves the use of coefficient of variation (CV), standardized anomaly index (SAI), precipitation concentration index (PCI), moving average and seasonality index (SI). As for rainy years, they exceed 40% at all stations, except Dar el Beïda, Djelfa, and Gafsa. Depending on data position in relation to limit values, the years are considered as(i)very dry, below the first quintile;(ii)dry, between the first and the second quintile;(iii)normal with trends towards drought, between the second quantile and the third quintile;(iv)rainy, between the third and the fourth quintile;(v)very rainy, above the fourth quintile. Results show a rain resumption observed in the recent years over the Sahelian region and a convincing link with the surface temperature of the Atlantic Ocean. CV is defined as the ratio of standard deviation to mean in percent, where mean and standard deviation are estimat - ed from rainfall data. Series of rainfall intensities at different A decrease is recorded only at three stations (Dar el Beïda, Djelfa, and Gafsa), while, for Constantine, Marrakech, and Sfax, stabilisation of values of 0% can be noted. Indeed, precipitation deficits in these countries are intense and may persist for long periods of time (1980–1987, 1991–1994, and 1998–2001). At the same time, Algeria and Tunisia, which are part of the MENA region countries, have reached a state of absolute water scarcity. 6: 1754. Water 12, no. Six climate factors were found to drive part of the rainfall variability in the region, and their modeled effect upon rainfall occurrences and amounts resulted in general agreement with previous studies. A & Ogunjobi K. O. The long-term rainfall variability analysis shows that the dry and wet conditions in Peninsular Malaysia are not primarily governed by 15 the ENSO events. In the Moroccan South, observation data revealed a return towards more humid conditions in the Tafilet oasis [43–46] and a reinstatement of several “Foggaras” (a traditional hydraulic system affected by past climatic droughts). Analysis of Rainfall Variability: Analysis Variation of rain-fall is important for planning and management of water resource intervention. The return of drought conditions is noted in 2007, in 2008 (index above −0.5), and in 2012 (index equal to −1.25). On the Atlantic coast, Casablanca and Safi are the other two stations in this vast country that manifest a stable trend of extreme years regarding this last category. The purpose of this article is to show the trend of rainfall over nearly half a century and to detect the date of changes of cycles. Figure 6, developed starting from the mobile average of all stations studied, sums up the main 3 stages that have affected Maghreb pluviometry during the last 44 years. Indeed, from 2008 to 2010, the percentage of rainy and very rainy years goes from 78.57% to 85.71% and 92.85%. 15-16, pp. The rise of lowest temperatures () is however more evident in this part of North Africa [24–26]. Analysis of Rainfall Variability Adaptation Strategies Employed by Wheat Farmers in Narok County, Kenya. Such question is difficult to answer today, but climate data and information concerning the hydraulics and agriculture of Maghreb confirm a completely unique situation in this vast area of North Africa. Thus, 2013 is one of the warmest years recorded in Tunisia since 1950 [23]. For all Moroccan stations studied, the proportion of dry and very dry years reaches almost 56%, while rainy and very rainy years account for a little more than a quarter, with 24%. IPCC (Intergovernmental Panel on Climate Change) GIEC, Changements climatiques en 2013, Les éléments scientifiques, résumé à l'intention des décideurs, service d'appui technique du groupe de travail I GTI, 2013. The effects of climate changes are also manifested in this country by extreme events (a succession of hot episodes in 2015 with a threshold temperature of 50°C exceeded at Ourgla on August 2nd 2015 and of snowfall in the Assekrêm mountains in Hoggar massif located in southern Algeria, a very rare fact never observed since 1945). MGCTI, classification of annual precipitation according to quintiles Q1, Q2, Q3, Q4, and Q5 (measurement period from 1970 to 2013). Our understanding of what controls rainfall variability and change is worryingly poor. In the Middle Moroccan Atlas, a situation may be noted which differs from that described for the central Moroccan region [29]. Our dedicated information section provides allows you to learn more about MDPI. M. Giannakopoulos, M. Bindi, M. Moriondo, and T. Tin, “Climate change impacts in the Mediterranean resulting from a 2°C global temperature rise,” A Report for WWF, G. Tselioudis, C. Zerefos, P. Zanis, P. Repapis, and I. Kapespmenakis, “Future trends in Mediterranean precipitation and possible connections with the phase pf the North Atlantic Oscillation,” in, M. Dubrovský, M. Hayes, P. Duce, M. Trnka, M. Svoboda, and P. Zara, “Multi-GCM projections of future drought and climate variability indicators for the Mediterranean region,”, P. Alpert, T. Ben-Gai, A. Baharad et al., “The paradoxical increase of Mediterranean extreme daily rainfall in spite of decrease in total values,”. When estimating the impact of rainfall variability, we focus on one specific type of variability: variation from year to year. Characteristic periods is less obvious because three-quarters of the series provide evidence of change of trend for this phase almost! 8 years planning and management of water for almost 290 million people analysis! Malaysia are not consistent with these predictions majority of Africa ’ s population is dependent on rain-fed subsistence... 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