This peculiarity makes the identification of long-term significant trends difficult [38] and shows the need to study the precipitation trend according to a global regional approach which minimises the topoclimate effect and is informed of the spatiotemporal distribution of precipitation cycles. A first stage of strong variability in 1970–1986. It provides a simple and effective way to establish a multivariate typology based on observations of the user. The same evolution may also be encountered in the intra-Tellian plains and basins [34]. This investigation is based on the calculation of the reduced centered index and the chronological graphical method of processing information (MGCTI) of “Bertin matrix” type. A little more than 60% of rainfall accumulations recorded at various stations are considered as dry or very dry. We use cookies on our website to ensure you get the best experience. ANALYSIS OF HISTORIC RAINFALL DATA FOR ANGOLA TO IMPROVE UNDERSTANDING OF RAINFALL VARIABILITY AND ITS IMPLICATIONS FOR FLOODING AND EROSION A WORKING PAPER OF THE PROJECT ON “WATER RESOURCE MANAGEMENT UNDER CHANGING CLIMATE IN ANGOLA’S COASTAL SETTLEMENTS” DEVELOPMENT WORKSHOP ANGOLA January 2014 . The last period (2002–2011) of the precipitation series is considered as wet (60% of the years recorded a positive index). (i)The analysis of the decade 1982–1991 (map shown in Figure 3(a)) shows the predominance of drought conditions in nineteen stations which record more than 50% dry and very dry years and only 7 which correspond to wet and wetter conditions for a little over a half of the duration of the period studied. (v)The stage covering the 1998–2001 period is marked by the return of drastic conditions. Indeed, from 2008 to 2010, the percentage of rainy and very rainy years goes from 78.57% to 85.71% and 92.85%. It is a period of severe drought which marks a large part of the Moroccan territory. The results also show the beginning of a gradual return to wetter conditions since the early 2000s in Algeria and Tunisia and from 2008 for Morocco (this trend is confirmed by recent agricultural production data in 2011/2012 and 2012/2013). Current observations in the three countries of central Maghreb (Morocco, Algeria, and Tunisia) are not consistent with these predictions. Dubrovský et al. Content uploaded by Ataur Goni Polash. This investigation is based on the calculation of the reduced centered index and the chronological graphical method of processing information (MGCTI) of “Bertin matrix” type. If, on a global scale, the increase in temperatures is unquestionable, the evolution of world pluviometry is much more contrasting as it is subject to a strong spatiotemporal variability. 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. The authors declare that they have no competing interests. When estimating the impact of rainfall variability, we focus on one specific type of variability: variation from year to year. The values are relatively high for 1982 (−1.12), 1983 (−1.21), and 1986 (−0.93). These rains ensured a record cereal production of 80 million quintals (for 2009/2010). Spatio-Temporal Rainfall Variability and Rainstorm Analysis over the Goa State, India . Abstract . You seem to have javascript disabled. 63, No. This variability has assumed a more pronounced dimension as a result of climate change. Rainy and very rainy years only account for 22.90%. West Africa; climate change; rainfall variability, Help us to further improve by taking part in this short 5 minute survey, Improving Inter-Laboratory Reproducibility in Measurement of Biochemical Methane Potential (BMP), Riparian Ground Beetles (Coleoptera) on the Banks of Running and Standing Waters, Indirect Impact Assessment of Pluvial Flooding in Urban Areas Using a Graph-Based Approach: The Mexico City Case Study, Long-Term Consequences of Water Pumping on the Ecosystem Functioning of Lake Sekšu, Latvia, Water Quality of Freshwater Ecosystems in a Temperate Climate. This last trend is also confirmed by [32] for north-eastern Tunisia. 2016, Article ID 7230450, 12 pages, 2016., 1UMR CNRS 6228 IDEES, University of Rouen, Rouen, France, 2Department of Geography, “Valahia” University, Târgovişte, Romania. This variability has assumed a more pronounced dimension as a result of climate change. At the same time, one may note the low values of rainy and very rainy years that reach 50% only at Skikda, Biskra, and Tétouan and are below this level at the remaining stations. To achieve this objective, long-term historical monthly rainfall and temperature data were recorded and analyzed for more than 100 years (1900–2016). 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%. Rainfall data of some terrestrial observations networks, on the south shore of the western Mediterranean basin, confirm this change for the last decade. At the same time, the temperature trend continues to be rising (despite a slight cooling of values recorded during the last years). This method was used for the first time in 2013 [24]. The monthly precipitation data were provided by the Meteorological Services “The National Office of National Meteorology (ONM) for Algeria, the National Meteorological Institute (INM) for Tunisia, and the National Directorate of Meteorology (DNM) for Morocco”. By Akinsanola A. At the same time, rainy and very rainy years show a rising trend confirmed starting with this last date (Figure 5(b)). Variability of rainfall can be used to characterize the climate of a region. The “RI” is calculated as follows: where is year value, is the series average, and is standard deviation. This article aims to analyze the precipitation trend for more than forty years of measurements on a wide northern strip in central Maghreb (Morocco, Algeria, and Tunisia). The signs of change are extremely eloquent for the latest years in all this region of North Africa, as evidenced by the rainfall observed between September 2008 and September 2009 In Morocco [42]. The dry and very dry classes represent just over 39% of years. 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 of this precipitation series (2003–2013), in which 82% of the years have a positive regional index, is described as rainy. 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). Chiara Ambrosino 1 , Richard E. Chandler 2 , and Martin C. Todd 3 View More View Less. However, a positive trend of annual rainfall was observed at Addis Zemen (1.81 mm/year). 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). This diversity of scientific opinions confirms the spatiotemporal variability of the Mediterranean pluviometry and particularly on the south shore of the basin [36, 37]. Complete analysis of rainfall events requires a study of both its spatial and temporal extents. It is shown that the convective scale variability is strongly influencing the spatial pattern of rainfields at larger time and spatial scales. Copyright © 2016 Zeineddine Nouaceur and Ovidiu Murărescu. Our analysis has several caveats. To get an overview of global rainfall variability, a pixel-by-pixel classification has been performed. Our understanding of what controls rainfall variability and change is worryingly poor. Okba, and A. Taous, “Caractérisation des évènements pluviométriques extrêmes dans le Moyen Atlas marocain et ses marges,” in, K. Khomsi, G. Mahe, Y. Tramblay, M. Sinan, and M. Snoussi, “Trends in rainfall and temperature extremes in Morocco,”, B. Laignel, Z. Nouaceur, H. Jemai, H. Abida, M. Ellouze, and I. Turki, “Vers un retour des pluies dans le nord-est tunisien?” in, N. Fehri, “L'aggravation du risque d'inondation en Tunisie: éléments de réflexion,”, L. Henia and Z. Hlaoui, “La pluviométrie dans les plaines et bassins intratelliens en Tunisie: évolution récente et projection dans le futur,” in, S. Jebari, R. R. Berndtsson, F. Lebdi, and A. Akissa Bahri, “Sediment, discharge and precipitation variation in the wadi Mellegue catchment during the 50 past years, Actes des dixièmes Journées Scientifiques de l'INRGREF, Hammamet 21-22 novembre 2007 Exploitation des ressources en eau pentru une agriculture durable,”, C. Norrant-Romand and A. Douguédroit, “Significant rainfall decreases and variations of the atmospheric circulation in the Mediterranean (1950–2000),”, E. Morin, “To know what we cannot know: global mapping of minimal detectable absolute trends in annual precipitation,”, Z. Nouaceur, B. Laignel, and I. Turki, “Changement climatique en Afrique du Nord : vers des conditions plus chaudes et plus humides, dans le Moyen Atlas Marocain et ses marges,” in, Z. Nouaceur, B. Laignel, and I. Turki, “Changement climatique au Sahel: des conditions plus chaudes et plus humides en Mauritanie?”, Z. Nouaceur and B. Laignel, “Caractérisation des évènements pluviométriques extrêmes sur la rive Sud du bassin méditerranéen: étude du cas du quart nord-est algérien,” in. For 2014, the filling of dams in operation reached nationwide a level of 72.38%, while westward, in areas that were affected by disturbances, an exceptional percentage of filling of 87% was noted. Check the following websites: WMO, World Meteorological Organisation: ONM, Office National de la Météorologie (Algeria): Direction de la Météorologie Nationale (Morocco): IMN, Institut de la Météorologie Nationale (Tunisia): NCDC, National Climatic Data Center: Series of rainfall intensities at different To complete the preliminary analysis, an analysis of variance (ANOVA) was used to indicate the predictability of the daily rainfall sequence. MGCTI, classification of annual precipitation according to quintiles Q1, Q2, Q3, Q4, and Q5 (measurement period from 1970 to 2013). The MGCTI is developed to facilitate the interpretation of the statistical results for the Mediterranean rainfall analysis, due to the high variability affecting this parameter. Author content. The analysis of precipitation evolution in central Maghreb (Morocco, Algeria, and Tunisia) revealed a significant variability typical of the Mediterranean climate (which is stronger for the last two countries). A second stage starts in 1987 and finishes in 2002. A printed edition of this Special Issue is available at, UMR IDÉES CNRS 6266, Rouen University, 76821 Mont Saint Aignan CEDEX, France, Department of Geography, Valahia University, 130001 Târgovişte, Romania. Figure 3 was completed by starting from the decennial averages of the categories of rainy and very rainy, dry and very dry years, and normal averages, calculated for the 1982–2011 interval, confirming the previous arguments for the return of rainfall conditions in central Maghreb. Differences between the last two decades (rainy and very rainy years and dry and very dry years). Ministry of Energy, Mines, Water and Environment, Ministère de l'Energie, des Mines, de l'Eau et de l'Approvisionnement, 2008-2009, 2009-2010, 2010-2011, 2011-2012, 201-2013. A sequence of three rainy years (1971–1973) can be noted at the beginning of the series, while, for the rest of the period, trend inversions (dry year, rainy year) are for two successive years at most. On the whole, this area is characterised by a well-defined summer drought and, depending on the subregions, by a maximum precipitation in autumn or winter [13]. The Bertin matrix is a manual and visual method of classification of information based on data. At the same time, this agricultural campaign ensured a new record cereal production evaluated at 97 million quintals. The National Climatic Data Center, NCDC, considers the year 2014 as the warmest ever recorded, with an anomaly of +0.69°C (calculated for the period 1880–2014) [2]. This study showed the simplicity and clarity of the results obtained with the MGCTI method. In the Middle Moroccan Atlas, a situation may be noted which differs from that described for the central Moroccan region [29]. The beginning of the period tends less to this oscillation (a sequence of three rainy years is noticeable from 1971 to 1973). Sign up here as a reviewer to help fast-track new submissions. Ruf, and M.-J. According to Chidozie et al, rainfall variability increases from … 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. 6: 1754. The data were analyzed for the occurrences of abrupt changes in temperature and Spatial distribution of precipitation stations used for this study. These numbers thus indicate an increase of years in the first class of +25% as compared to the previous period and a regress of the arid and very arid class of −23.64%. CV is defined as the ratio of standard deviation to mean in percent, where mean and standard deviation are estimat - ed from rainfall data. In Algeria, the severe disturbances (which lead to a pluviometry of over 30 mm/24 h) are on the rise in the last years (data, ONM). The Bertin matrix was introduced to harmonize and consolidate information after the statistical treatment. A little more than 60% of rainfall accumulations recorded at various stations are considered as dry or very dry. 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). The IPCC climate models predict, for the Maghreb countries, lower rainfall and increased aridity. Precipitation data recorded in 1970–2013 in Tunisia (Figure 2) are characterised by a significant variability previously emphasized during the study of Morocco and Algeria series. The regional index is positive for almost 53% of years and negative for the remaining 47%. The analysis of the decade 1982–1991 (map shown in Figure, The 1992–2001 period (map shown in Figure. This new period marks a break from past droughty periods despite the return, once in a while, of deficient years (e.g., in 2005 and 2006 for Algeria and Tunisia and 2006, 2007, and 2011 for Morocco). The beginning of the period tends less to this oscillation (a sequence of three rainy years is noticeable from 1971 to 1973). (ii)In Algeria, the Constantine, Annaba, and Skikda stations located in the east of the country record a rising trend of 10% for the first station and stabilisation of values for the last two. 40, pp. Alpert et al. The return of drought conditions is noted in 2007, in 2008 (index above −0.5), and in 2012 (index equal to −1.25). The years belonging to the dry and very dry class totalize almost 55% for all stations. From 1991 to 1994, rainfall accumulations become negative again. At times, this rainfall return occurs in extreme episodes as was the case of the recent floods (November 2014) which hit central and south-western Morocco (Agadir, Guelmin, and Marrakech areas). RAINFALL VARIABILITY AND TREND ANALYSIS OF MULTIANNUAL . 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. The results of several studies on rainfall evolution in many areas of the globe, as it happens in North Africa, show that climate change translates into wetter conditions [5, 6] as well as into a rainfall increase and repetition of extreme events (perceptible in the recent decades 1991–2010) [4, 7–9]. Recent analysis of the rainfall base for the eastern transect (Malou R. 2002; Malou R. [...] 2004) has allowed establishment [...] of future bases for rainfall variability in the east of the [...] country (Kolda and Bakel weather [...] stations) where models predict greatest change. Abstract-This study investigates rainfall and temperature variabilities in Nigeria using observations of air temperature (C) and rainfall (mm) from 25 synoptic stations from 1971o -2000 (30years). GIS maintains the spatial location of sampling points, and … Almost 50% of annual rainfall accumulations are considered as wet and very wet. To determine the typical breaks and periods, a second procedure is conducted. 16, 2007, M. El Faiz and T. Ruf, “An introduction to the khettara in morocco: two contrasting cases,” in, Institut de Recherche pour le Développement (IRD), “Les réseaux d’eau anciens ressuscitent en Méditerranée,”, M. Mahdane, S. Lanau, Th. Nouaceur, Z.; Murarescu, O. Rainfall Variability and Trend Analysis of Rainfall in West Africa (Senegal, Mauritania, Burkina Faso). Thirty-five stations (14 in Morocco, 12 in Algeria, and 9 in Tunisia) which provide a common period of measurements were chosen for this study (1970–2013 for Algeria and Tunisia and 1970–2011 for Morocco) (Figure 1). The maximum and minimum monthly rainfall records did not exhibit a statistically significant trend. See further details. 2020. [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. This method has been successfully tested in many North African regions [28, 29, 32, 39] and in the Sahel [40]. CV is calculated by the standard deviation divided by the mean annual of rainfall over the study period. Z. Nouaceur, B. Laignel, and I. Turki, “Changements climatiques au Maghreb: vers des conditions plus humides et plus chaudes sur le littoral algérien ?”, Z. Nouaceur, B. Laignel, and I. Turki, “Changement climatique en Afrique du Nord: vers des conditions plus chaudes et plus humides,” in, M. G. Donat, T. C. Peterson, M. Brunet et al., “Changes in extreme temperature and precipitation in the Arab region: long-term trends and variability related to ENSO and NAO,”, A. Sebbar, W. Badri, H. Fougrach, M. Hsain, and A. Saloui, “Étude de la variabilité du régime pluviométrique au Maroc septentrional (1935–2004),”, Z. Nouaceur, “Évaluation des changements climatiques au Maghreb, Étude du cas des régions du quart nord-est algérien,” in, M. Amyay, Z. Nouaceur, A. Tribak, Kh. In Algeria, the Constantine, Annaba, and Skikda stations located in the east of the country record a rising trend of 10% for the first station and stabilisation of values for the last two. 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. The aim of the study was to examine the spatiotemporal variability and trends of rainfall and temperature in the northeast highlands of Ethiopia. As explained in section 3.2, the variability of rainfall in arid and semi-arid areas is considerable. This decade contains 70% of the years with positive regional index. The statements, opinions and data contained in the journal, © 1996-2020 MDPI (Basel, Switzerland) unless otherwise stated. The variability of short-term global climate is generally associated with coupling phases of oceanic and atmospheric phenomena including El Niño Southern Oscillation (ENSO) and the North Atlantic Oscillation (NAO). WMO (Wolrd Meteorological Organization), “Statement on the status of global climate in 2012,” Tech. We will be providing unlimited waivers of publication charges for accepted research articles as well as case reports and case series related to COVID-19. 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. ANOVA decomposes the variation into “systematic” and “random” components. This study concerns the West African Sahel. Giorgi and Lionello [11] estimate that significant Mediterranean rainfall decline is expected in connection with intensification of the anticyclonic circulation and a northward shift of the string of cyclonic depression areas. Analysis of Historic Rainfall … A & Ogunjobi K. O. 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. In Morocco, only one station (Marrakech) is not keeping up with the return of rainy conditions as it records a rise in dry and very dry years of 10%. Contribution of seasonal rainfall to the total annual rainfall in percent (CT) for each station is also computed. To demonstrate this new trend, a detailed regional analysis of rainfall evolution is conducted. This matrix is used to group the data that have similarities according to all the criteria studied. During summer, rainfall is scarce. The highest values are noted at the beginning of the period (+1.57 for 1970 and +1.09 for 1973). 1*, S.S. Mulye. [30] find no statistical significancy in the cumulative and extreme rainfall trends (summer and winter events) in 9 stations of this last country. The percentage of rainy and very rainy years recorded at all stations (55.72%) is in net increase, while dry and very dry years, with 20.61%, are in net decrease as compared to the previous period. Abstract; Keywords ; References; PDF; The purpose of this study was to analyze the adaptation strategies employed by wheat farmers as a result of seasonal rainfall variability in Narok County, Kenya. The projection of the result on a graph allows for the visualisation of the evolution of the phenomenon on a regional scale in a first stage and, in a second stage, for the determination of data on breaks and trend change. The stage covering the 1998–2001 period is marked by the return of drastic conditions. Subscribe to receive issue release notifications and newsletters from MDPI journals, You can make submissions to other journals. According to this mode of traffic, the depressions corridor withdraws further south and thus affects the Mediterranean regions of the south shore which will be wetter. It reveals the importance of positive differences which indicate an increase of the former category in 83% of the stations.

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