In this paper, we test this method on a larger area consisting of different climatic regions of North Africa (more than 30 stations). The results show extreme variability of this parameter and the severe past drought (more intense for Morocco, in which the drastic conditions from the seventies are observed). Hydrological investigation over a large area requires assimilation of information from many sites each with a unique geographic location (Shahid et al., 2000, Shahid and Nath, 2002). It provides a simple and effective way to establish a multivariate typology based on observations of the user. At the same time, the temperature trend continues to be rising (despite a slight cooling of values recorded during the last years). 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). The percentage of average year reaches 25.71%, while, during dry years, it represents 27.14%. 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%. As the area experiences a bimodal rainfall regime, the CAD for each data set is further grouped into the major season, between March and July, and minor season, between Septembe… 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 importance of this water mass on a regional scale explains the vast expanse in space of the Mediterranean climate domain. The spatial variability of rainfall was estimated using a coefficient of variation (CV) over the IGB . 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. 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. A number of techniques have been developed for the variability and trend analysis of the rainfall time series. the rainfall variability in the recent past. This variability has assumed a more pronounced dimension as a result of climate change. The statements, opinions and data contained in the journals are solely Rainfall variability was analyzed using the data of 100 years from 1918 to 2017, of Batticaloa The rise of lowest temperatures () is however more evident in this part of North Africa [24–26]. However, the results show a contrary trend to climate models predictions [27, 28]. 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%. The last map (Figure 4) displays the differences between the last two decades (1992–2001 and 2002–2011), between precipitation accumulations of rainy and very rainy years and dry and very dry years. The mesoscale variability of the Sahelian rainfall is analysed from a series of 30 high time resolution rainfall series covering 13 years and a 110 × 160 km2 area in the region of Niamey. Rainfall variability is expressed by the coefficient of variation (CV). The return of drought conditions is noted in 2007, in 2008 (index above −0.5), and in 2012 (index equal to −1.25). The first authors assign a tropical precipitation origin to the return of rains observed at the Moroccan stations of Safi and El-Jadida, while, within the whole of the central region of Morocco, drought conditions prevail. The minimum, maximum and mean temperatures have increased significantly for most of the stations. 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. Variability of rainfall has been computed using coefficient of variation (CV) (see Hare 1983), standardized rainfall anomaly (SRA) (see Agnew & Chappel 1999), precipitation concentration index (PCI) [28], and standardized precipitation index (SPI) [29]. Climatic drought recorded in Algeria and Tunisia is shorter (1987–2002) and the cycles of years of deficits not only are synchronised between the two countries but also are less extended in time and they never exceed three consecutive dry years (1987–1989, 1993-1994, and 2000–2002). A period qualified as wet is visible on the matrix during 1970–1979. The “RI” is calculated as follows: where is year value, is the series average, and is standard deviation. The persistence of drought conditions never exceeds three consecutive years. Differences between the last two decades (rainy and very rainy years and dry and very dry years). 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). To complete the preliminary analysis, an analysis of variance (ANOVA) was used to indicate the predictability of the daily rainfall sequence. WMO (Wolrd Meteorological Organization), “Statement on the status of global climate in 2012,” Tech. A little more than 60% of rainfall accumulations recorded at various stations are considered as dry or very dry. 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. Our analysis has several caveats. 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. The dry and very dry classes represent just over 39% of years. 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. The dry and very dry classes represent just over 39% of years. (iii)The regional index reaches, during this final year, one of the lowest values of the series, −1.41. 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). Do these facts announce a new climate phase which marks a break from past drastic conditions? The results of statistical and graphical processing of central Maghreb pluviometry show strong variability (typical of the Mediterranean climatic domain) and an organisation structured into three main climatic periods (Figure 2). Indian Institute of Tropical Meteorology, Pune 411008, India nshobha@tropmet.res.in . Face the future,”, M. H. I. Dore, “Climate change and changes in global precipitation patterns: what do we know?”, L. V. Alexander, X. Zhang, T. C. Peterson et al., “Global observed changes in daily climate extremes of temperature and precipitation,”, M. New, M. Todd, M. Hulme, and P. Jones, “Precipitation measurements and trends in the twentieth century,”, J. H. Christensen, B. Hewitson, A. Busuioc et al., “Regional climate projections,” in, S. Planton, M. Déqué, H. Douville, and B. Spagnoli, “Impact du réchauffement climatique sur le cycle hydrologique,”, F. Giorgi and P. Lionello, “Climate change projections for the Mediterranean region,”, Blue Plan, Environment and development in Mediterranean, Climate change in the Mediterranean, no. While El Niño Southern Oscillation (ENSO) affects climate variability in the world, the North Atlantic Oscillation (NAO) is the climate model dominant in the North Atlantic region. [18] based on the future projections of regional climate model RACMO2/KNMI show that annual precipitation within the majority of Mediterranean is very likely to decrease on an average of 20%, during the period 2071–2100 compared to 1961–1990, under scenario “SRES” “A1B.” The works of Giannakopoulos et al. The Bertin matrix was introduced to harmonize and consolidate information after the statistical treatment. 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; 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. On the whole, this last stage distinguishes itself through an uninterrupted sequence of 7 years (2007–2013) with positive regional indices. Rainfall variability on the other hand is the degree to which rainfall amounts vary across an area or through time. Research in the group aims to provide a more solid understanding of climate processes in key rainfall regions such as southern Africa, central Africa/Congo Basin, East Africa and the Sahel. 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%. Philandras et al. Previous research shows that intraseasonal rainfall variability can have an even larger impact on crop yields. The years belonging to the dry and very dry class totalize almost 55% for all stations. Rainy and very rainy years only account for 22.90%. 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). Rainfall is a dynamic phenomenon, which changes over time and space. Four years stand out through negative indices which exceed −1: 1988 (−1.36), 1989 (−1.03), 1993 (−1.46), 2000 (−1.68), and 2001 (−1.46). Variability of rainfall can be used to characterize the climate of a region. The values are relatively high for 1982 (−1.12), 1983 (−1.21), and 1986 (−0.93). Analysis of Rainfall Variability in Sylhet Region of Bangladesh.pdf. The regional index is positive for almost 53% of years and negative for the remaining 47%. The World Meteorological Organisation [3] considers the period 2011–2015 as the hottest on record, and the year 2015 as the hottest since modern observations began in the late 1800s. The stage covering the 1998–2001 period is marked by the return of drastic conditions. Thus, 2013 is one of the warmest years recorded in Tunisia since 1950 [23]. 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. S. Nandargi. 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 . Analysis of Historic Rainfall … This provides the concordant results (even rainfall character for all stations studied in the same year) but also identifies conflicting information (different characters between stations for the same year). (iv)From 1995 to 1997, a short wet period marks the Moroccan pluviometry, with a spectacular increase of pluviometry (the regional index reaches +1.37 in 1996, one of the highest values of the first three decades of this series). [30] find no statistical significancy in the cumulative and extreme rainfall trends (summer and winter events) in 9 stations of this last country. To demonstrate this new trend, a detailed regional analysis of rainfall evolution is conducted. 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. On that way, areas with similar climatological characteristics can be identified. The second period is marked by a dry trend which lasts 16 years on this territory. Valony, Gouvernance d'une oasis dont l'eau provient quasi exclusivement de l'exploitation traditionnelle des galeries drainantes, les khettaras: le cas de SKOURA au Maroc, Atelier international à Tunis 4–6, Novembre 2010, A. Daoud, “Retour d'expérience sur les inondations dans l'agglomération de Sfax (Tunisie méridionale) de 1982 à 2009: de la prévention à la territorialisation du risque,”, J. I. López-Moreno, S. M. Vicente-Serrano, E. Morán-Tejeda, J. Lorenzo-Lacruz, A. Kenawy, and M. Beniston, “Effects of the North Atlantic Oscillation (NAO) on combined temperature and precipitation winter modes in the Mediterranean mountains: observed relationships and projections for the 21st century,”. 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]. The last period of this precipitation series (2003–2013), in which 82% of the years have a positive regional index, is described as rainy. 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). In this season, the Azores anticyclone moves north. 2097-2123. The rainy season begins in the fall and continues to the spring. Content uploaded by Ataur Goni Polash. A comparative study with the SPI (Standard Precipitation Index) method for detecting climate drought was conducted in 2015 [41]. At the same time, Algeria and Tunisia, which are part of the MENA region countries, have reached a state of absolute water scarcity. The First Stage. 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. This large inner sea stretching from the Strait of Gibraltar to the Lebanese coasts over an area of almost 4,000 km has a total surface of 2.51 million km. 2016, Article ID 7230450, 12 pages, 2016. https://doi.org/10.1155/2016/7230450, 1UMR CNRS 6228 IDEES, University of Rouen, Rouen, France, 2Department of Geography, “Valahia” University, Târgovişte, Romania. 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. A little more than 60% of rainfall accumulations recorded at various stations are considered as dry or very dry. 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. 15-16, pp. 2 . 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. It is a period of severe drought which marks a large part of the Moroccan territory. The Third Stage. 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). Under these conditions, the depressions are pushed towards northern latitudes, which promotes the establishment of a dry and mild weather on the periphery of the Mediterranean basin and North African regions. This study concerns the West African Sahel. It represents a least in the region of high rainfall, whereas the largest in the region of scanty rainfall. Water 12, no. Rainfall data of some terrestrial observations networks, on the south shore of the western Mediterranean basin, confirm this change for the last decade. 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). Dubrovský et al. 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. (ii)From 1991 to 1994, rainfall accumulations become negative again. Ruf, and M.-J. We are committed to sharing findings related to COVID-19 as quickly as possible. Zeineddine Nouaceur 1, Ovidiu Murărescu 2, George Murătoreanu … In 1980, a new drier climatic phase began and lasted until 2001. Analysis of Rainfall and Temperature Variability Over Nigeria . MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The rise that occurred during the last decade (2003–2012) is +0.78°C (for a minimum of 0.72°C and a maximum of 0.85°C). 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). The maximum and minimum monthly rainfall records did not exhibit a statistically significant trend. These rains ensured a record cereal production of 80 million quintals (for 2009/2010). Rainy and very rainy years are evaluated for this phase at almost 48%, while dry and very dry years totalize 31.31%. This latter season is associated with the process of oceanic moisture transfer to the mainland (the West African Monsoon). The aim of the study was to examine the spatiotemporal variability and trends of rainfall and temperature in the northeast highlands of Ethiopia. The return of drought conditions is noted in 2007, in 2008 (index above −0.5), and in 2012 (index equal to −1.25). 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]. Indeed, from 2008 to 2010, the percentage of rainy and very rainy years goes from 78.57% to 85.71% and 92.85%. 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. Variability analysis involves the use of coefficient of variation (CV), standardized anomaly index (SAI), precipitation concentration index (PCI), moving average and seasonality index (SI). The regional index is positive for a period of 8 years. The years belonging to the dry and very dry class totalize almost 55% for all stations. This first period, just like that analyzed for Algeria, is characterised by an important variation of extreme years (two years, namely, 1981 with a negative index of −1.79% and 1982 with a positive index of +1.77, show this particularity). When the anticyclone retreats south, it leaves free the passage to the ocean disturbances affecting North Africa. When the signal fades or becomes negative, the pressure associated with the Azores high is lower compared to the normal value and, at the same time, the Icelandic Low is barely formed. Successive stages with the same trends exceed no more than three years (1987–1989 and 2000–2003 for negative indices and 1995–1997 for positive indices). The regional index reaches, during this final year, one of the lowest values of the series, −1.41. Variability of rainfall can be used to characterize the climate of a region. (ii)The second period is marked by a dry trend which lasts 16 years on this territory. This analysis highlights a break of chronological sequences during the most characteristic periods of the great drought of the 1980s (1981–1992) and a return of rains in the early 2000s (2001–2009). Series of rainfall intensities at different To demonstrate this new trend, a detailed regional analysis of rainfall evolution is conducted. The Second Stage. 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. [35] have emphasized the tendency of rainfall decline and higher efficiency of solid transport and flows over 50 years’ sequences (1960–2004). As for rainy years, they exceed 40% at all stations, except Dar el Beïda, Djelfa, and Gafsa. This new trend is still noticeable through a rise in intense precipitation events and a net increase of the number of floods (Sfax city very well illustrates this; the city was flooded twice in 1969 and 1982 and, despite important improvement works carried out in 1984 and the past years, it was flooded again in 2009 and 2013) [47]. 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. Figure 5(c) concerning the class of normal years allows one to note that the percentage of stations, after displaying a trend of decrease from 1995 to 2000, increases starting with this last date for Algeria and Tunisia but decreases for Moroccan stations, which confirms a steady return of the wet stage in this country (considering the previously developed arguments for the other two classes). 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. Three data sets, described as Climate Assessment Decade (CAD), of 10 years, ranging from 1985 to 1994, 1995 to 2004, and 2005 to 2014, were categorised to allow comparison of variation in rainfall distribution in the area. This first period, just like that analyzed for Algeria, is characterised by an important variation of extreme years (two years, namely, 1981 with a negative index of −1.79% and 1982 with a positive index of +1.77, show this particularity). See further details. The Sahelian climate is characterized by a long dry season and a rainy season which starts in June and ends in September–October. At the same time, the percentage of rainy and very rainy years at all stations reaches 52.38%. 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. An increasing trend of annual maximum temperature was … This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This last trend is also confirmed by [32] for north-eastern Tunisia. Analysis of Rainfall Variability Adaptation Strategies Employed by Wheat Farmers in Narok County, Kenya. Dry years reach 50% only at three stations (Marrakech, Sefrou, and Sfax). As explained in section 3.2, the variability of rainfall in arid and semi-arid areas is considerable. The MGCTI and its graphic representation allow a chronological reading and a spatial analysis of the phenomenon. 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”. In the Middle Moroccan Atlas, a situation may be noted which differs from that described for the central Moroccan region [29]. 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 MGTCI graphical matrix shows once more three major characteristic periods:(i)The first stage starts in 1970 and finishes in 1986 and is marked by a lack of trend. The last years of the series provide evidence of change of trend for this decade. The combined effect of climate change and anthropic impact would entail a lack of water for almost 290 million people. In central Maghreb (Morocco, Algeria, and Tunisia), the rise in temperature is pursuant to the global situation. Understanding the decadal and/or annual variability and distributions of rainfall of a region is important and useful especially for agricultural activities. 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). The regional index is negative for more than 47% of the years as opposed to 52.94% for positive values. The Bertin matrix is a manual and visual method of classification of information based on data. Alpert et al. It reveals the importance of positive differences which indicate an increase of the former category in 83% of the stations. 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. The northernmost parts in winter analysis shows that the dry and very rainy years and dry very. 23 ] to indicate the predictability of the period tends less to precipitation. An analysis of the annual rainfall was observed at Addis Zemen ( 1.81 )... 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