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RAGHAVENDRA, V. K. "Trends and periodicities of rainfall in sub-divisions of Maharashtra State". MAUSAM 25, n.º 2 (7 de febrero de 2022): 197–210. http://dx.doi.org/10.54302/mausam.v25i2.5194.
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The Maharashtra State of India is divided into four meteorological sub-divisions, viz., Konkan, Madhya Maharashtra, Marathwada and Vidarbha. Of these, Madhya Maharashtra and Marathwada are prone to droughts. The principal rainy season is the monsoon season of June to September when over 80 per cent of the annual rainfall is received. The coefficient of variation is about 20 per cent for the annual and monsoon rainfall except in Marathwada where it is 25 per cent. The annual and monsoon rainfalls follow the normal distribution for their yearly frequencies. In this region the annual and the monsoon rainfall series are highly correlated. In the loss drought prone sub-division of Konkan, the annual and monsoon rainfalls show a 100 year cycle. In all the sub-divisions the successive years' rainfalls are not dependent. The trend as revealed by fitting of orthogonal polynomials is shown as a quadratic curve for the annual and monsoon rainfalls of Konkan and Madhya, Maharashtra, the sub-divisions on either side of the Western Ghats. The low pass filter and Mann-Kendall test against randomness confirmed the trend in Konkan rainfall. The power spectral analysis of the data indicates the existence of long term trend for monsoon rainfall of Konkan, 60 year cycle for the annual rainfall of Konkan and Madhya Maharashtra, 30.year cycle for the annual and monsoon rainfall or Vidarbha, 20-year cycle for the monsoon rainfall of Marathwada, 15-year cycle for the monsoon rainfall of Madhya Maharashtra, 7.5-year cycle for the annual and monsoon rainfall of Marathwada.
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Stefanidis, Stefanos y Dimitrios Stathis. "Spatial and Temporal Rainfall Variability over the Mountainous Central Pindus (Greece)". Climate 6, n.º 3 (6 de septiembre de 2018): 75. http://dx.doi.org/10.3390/cli6030075.
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In this study, the authors evaluated the spatial and temporal variability of rainfall over the central Pindus mountain range. To accomplish this, long-term (1961–2016) monthly rainfall data from nine rain gauges were collected and analyzed. Seasonal and annual rainfall data were subjected to Mann–Kendall tests to assess the possible upward or downward statistically significant trends and to change-point analyses to detect whether a change in the rainfall time series mean had taken place. Additionally, Sen’s slope method was used to estimate the trend magnitude, whereas multiple regression models were developed to determine the relationship between rainfall and geomorphological factors. The results showed decreasing trends in annual, winter, and spring rainfalls and increasing trends in autumn and summer rainfalls, both not statistically significant, for most stations. Rainfall non-stationarity started to occur in the middle of the 1960s for the annual, autumn, spring, and summer rainfalls and in the early 1970s for the winter rainfall in most of the stations. In addition, the average magnitude trend per decade is approximately −1.9%, −3.2%, +0.7%, +0.2%, and +2.4% for annual, winter, autumn, spring, and summer rainfalls, respectively. The multiple regression model can explain 62.2% of the spatial variability in annual rainfall, 58.9% of variability in winter, 75.9% of variability in autumn, 55.1% of variability in spring, and 32.2% of variability in summer. Moreover, rainfall spatial distribution maps were produced using the ordinary kriging method, through GIS software, representing the major rainfall range within the mountainous catchment of the study area.
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Liao, Yifan, Bingzhang Lin, Xiaoyang Chen y Hui Ding. "A New Look at Storm Separation Technique in Estimation of Probable Maximum Precipitation in Mountainous Areas". Water 12, n.º 4 (20 de abril de 2020): 1177. http://dx.doi.org/10.3390/w12041177.
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Storm separation is a key step when carrying out storm transposition analysis for Probable Maximum Precipitation (PMP) estimation in mountainous areas. The World Meteorological Organization (WMO) has recommended the step-duration-orographic-intensification-factor (SDOIF) method since 2009 as an effective storm separation technique to identify the amounts of precipitation caused by topography from those caused by atmospheric dynamics. The orographic intensification factors (OIFs) are usually developed based on annual maximum rainfall series under such assumption that the mechanism of annual maximum rainfalls is close to that of the PMP-level rainfall. In this paper, an alternative storm separation technique using rainfall quantiles, instead of annual maximum rainfalls, with rare return periods estimated via Regional L-moments Analysis (RLMA) to calculate the OIFs is proposed. Based on Taiwan’s historical 4- and 24-h precipitation data, comparisons of the OIFs obtained from annual maximum rainfalls with that from extreme rainfall quantiles at different return periods, as well as the PMP estimates of Hong Kong from transposing the different corresponding separated nonorographic rainfalls, were conducted. The results show that the OIFs obtained from rainfall quantiles with certain rare probabilities are more stable and reasonable in terms of stability and spatial distribution pattern.
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Ledingham, Jamie, David Archer, Elizabeth Lewis, Hayley Fowler y Chris Kilsby. "Contrasting seasonality of storm rainfall and flood runoff in the UK and some implications for rainfall-runoff methods of flood estimation". Hydrology Research 50, n.º 5 (14 de agosto de 2019): 1309–23. http://dx.doi.org/10.2166/nh.2019.040.
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Abstract Using data from 520 gauging stations in Britain and gridded rainfall datasets, the seasonality of storm rainfall and flood runoff is compared and mapped. Annual maximum (AMAX) daily rainfall occurs predominantly in summer, but AMAX floods occur most frequently in winter. Seasonal occurrences of annual daily rainfall and flood maxima differ by more than 50% in dry lowland catchments. The differences diminish with increasing catchment wetness, increase with rainfalls shorter than daily duration and are shown to depend primarily on catchment wetness, as illustrated by variations in mean annual rainfall. Over the whole dataset, only 34% of AMAX daily flood events are matched to daily rainfall annual maxima (and only 20% for 6-hour rainfall maxima). The discontinuity between rainfall maxima and flooding is explained by the consideration of coincident soil moisture storage. The results have serious implications for rainfall-runoff methods of flood risk estimation in the UK where estimation is based on a depth–duration–frequency model of rainfall highly biased to summer. It is concluded that inadequate treatment of the seasonality of rainfall and soil moisture seriously reduces the reliability of event-based flood estimation in Britain.
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Ologeh, I. y F. Adesina. "Evaluation of climate change as a major determinant of crop yield improvement in Nigeria". IOP Conference Series: Earth and Environmental Science 1077, n.º 1 (1 de septiembre de 2022): 012002. http://dx.doi.org/10.1088/1755-1315/1077/1/012002.
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Abstract Climate change has adversely affected agricultural productivity leading to decline in food production. The influence of climate change on crops and livestock persists despite irrigation, improved plant and animal hybrids. The continued dependence of agricultural production on climatic factors and the relative dependence of human existence on agricultural products create the need for a comprehensive consideration of the relationship between climate and crop production. This study measured the relationship between annual maize/yam yield as dependent variable and seasonal rainfall as independent variables in four states in Nigeria. It has been proven in the past that yearly rainfall value has no influence on annual crop yield, but seasonal or monthly rainfall does. There is a positive and significant relationship between summed up rainfalls of June/July/August and annual maize yields for the thirty-five years under study. The bi-monthly rainfall values did not influence a major part of total annual maize yield, as it records weak relationship with annual maize yield. On the other hand, bi-monthly rainfall values (May/June and July/August) have positive and significant relationship with annual yam yield. The first quarter- March/April/May rainfall values for each of the states have a positive and significant relationship with annual yam yield. This implies that the rainfall value for this quarter is very essential for annual yam yield for each of the states.
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Junges, Amanda H., Carolina Bremm y Denise C. Fontana. "Rainfall climatology, variability, and trends in Veranópolis, Rio Grande do Sul, Brazil". Revista Brasileira de Engenharia Agrícola e Ambiental 23, n.º 3 (marzo de 2019): 160–66. http://dx.doi.org/10.1590/1807-1929/agriambi.v23n3p160-166.
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ABSTRACT The objective of this study was to characterize the rainfall climatology in Veranópolis, Rio Grande do Sul, Brazil, through analyses of means, variabilities related to El Niño Southern Oscillation (ENSO), and temporal trends, using a 60-year data series (1956-2015). Descriptive statistics of annual, monthly and seasonal rainfall were used to characterize the rainfall climatology. The differences between seasons, and influence of ENSO were evaluated using analysis of variance and the Duncan’s test. Rainfall trends were evaluated by the Mann Kendall test. The local average annual rainfall is 1,683 mm and the average monthly rainfall is 140 mm, varying from 109 (May) to 182 mm (September). The annual rainfall has high interannual (standard deviation of 327 mm), monthly (60-100 mm) and seasonal (124-183 mm) variabilities, which should be considered in non-irrigated agricultural systems using rainfall as the main source of water supply to plants. Although autumn presents lower average rainfall (346 mm) than the other seasons, its average percentages were similar to the total annual rainfall (21-28%), and the rainfalls are well-distributed in the seasons. Differences between ENSO events occurred in the spring; La Niña years showed lower rainfall (385 mm) than El Niño (549 mm) and neutral (481 mm) years. The annual rainfall tended to increase by 6.3 mm per year (p < 0.01), with increases of 2.5 mm in spring and 1.9 mm in winter (p < 0.10) in the period analyzed.
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Yoo, Chul-Sang y Cheol-Soon Park. "Comparison of Annual Maximum Rainfall Series and Annual Maximum Independent Rainfall Event Series". Journal of Korea Water Resources Association 45, n.º 5 (31 de mayo de 2012): 431–44. http://dx.doi.org/10.3741/jkwra.2012.45.5.431.
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Whitehead, Peter J., Jeremy Russell-Smith y Cameron Yates. "Fire patterns in north Australian savannas: extending the reach of incentives for savanna fire emissions abatement". Rangeland Journal 36, n.º 4 (2014): 371. http://dx.doi.org/10.1071/rj13129.
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Anthropogenic fires in Australia’s fire-prone savannas produce up to 3% of the nation’s accountable greenhouse gas (GHG) emissions. Incentives to improve fire management have been created by a nationally accredited savanna burning emissions abatement methodology applying to 483 000 km2 of relatively high-rainfall (>1000 mm p.a.) regions. Drawing on 15 years of fire mapping, this paper assesses appropriate biophysical boundaries for a savanna burning methodology extended to cover lower-rainfall regions. We examine a large random sample of points with at least 300 mm of annual rainfall, to show that: (a) relative fire frequencies (percentage of years with fire) decline from 33.3% in higher-rainfall regions (>1000 mm) to straddling ~10% in the range 300–700 mm; (b) there are no marked discontinuities in fire frequency or fire seasonality down the rainfall gradient; (c) at all annual rainfalls, fire frequency is higher when rainfall is more strongly seasonal (very low rainfall in the driest quarter); (d) below 500 mm fire regimes are particularly variable and a large proportion of sampled sites had no fire over the study period; (e) fire is more likely to occur later in the fire season (generating relatively higher emissions) in the 600–700-mm annual rainfall band than in other parts of the rainfall gradient; (f) woodland savannas are most common above and predominantly grassland systems are more common below ~600-mm annual rainfall. We propose that development of a complementary lower-rainfall savanna burning methodology apply to regions between 600 and 1000-mm annual rainfall and ≤15 mm of rainfall in the driest quarter, adding an area more than 1.5 times the existing methodology’s coverage. Given greater variability in biophysical influences on fire regimes and observed levels of fire frequency within this lower-rainfall domain, we suggest that criteria for determining baseline (pre-project) periods require estimates of mean annual emissions equivalent in precision to the project on which the higher-rainfall methodology was based.
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Ahmad, Aimi Athirah, Fadhilah Yusof, Muhamad Radzali Mispan y Hasliana Kamaruddin. "Rainfall, evapotranspiration and rainfall deficit trend in Alor Setar, Malaysia". Malaysian Journal of Fundamental and Applied Sciences 13, n.º 4-1 (5 de diciembre de 2017): 400–404. http://dx.doi.org/10.11113/mjfas.v13n4-1.844.
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Rainfall and potential evapotranspiration are important variables in water balance study. Rainfall data were obtained from Malaysian Meteorological Department while estimates of potential evapotranspiration were calculated using Penman-Monteith method. Trend analysis of monthly and annual rainfall, potential evapotranspiration and rainfall deficit are essential to manage irrigation system in agricultural systems. This is because changes in trend of these parameters may affect the water cycle and ecosystem. Annual and monthly values of these variables were analysed from 1980-2009. Results indicated increasing trends of 16.2 mm yr-1 and 3.01 mm yr-1 for both annual rainfall and potential evapotranspiration, respectively. Consequently, these trends resulted in annual rainfall deficit of 1.69 mm per year.
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SEETHARAM, K. "Rainfall models – a study over Gangtok". MAUSAM 61, n.º 2 (27 de noviembre de 2021): 225–28. http://dx.doi.org/10.54302/mausam.v61i2.819.
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In this paper, the Pearsonian system of curves were fitted to the monthly rainfalls from January to December, in addition to the seasonal as well as annual rainfalls totalling to 14 data sets of the period 1957-2005 with 49 years of duration for the station Gangtok to determine the probability distribution function of these data sets. The study indicated that the monthly rainfall of July and summer monsoon seasonal rainfall did not fit in to any of the Pearsonian system of curves, but the monthly rainfalls of other months and the annual rainfalls of Gangtok station indicated to fit into Pearsonian type-I distribution which in other words is an uniform distribution. Anderson-Darling test was applied to for null hypothesis. The test indicated the acceptance of null-hypothesis. The statistics of the data sets and their probability distributions are discussed in this paper.
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Brychta, Jiří y Miloslav Janeček. "Determination of erosion rainfall criteria based on natural rainfall measurement and its impact on spatial distribution of rainfall erosivity in the Czech Republic". Soil and Water Research 14, No. 3 (27 de mayo de 2019): 153–62. http://dx.doi.org/10.17221/91/2018-swr.
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Rainfall erosivity is the main factor of the USLE or RUSLE equations. Its accuracy depends on recording precision and its temporal resolution, number of stations and their spatial distribution, length of recorded period, recorded period, erosion rainfall criteria, time step of rainfall intensity and interpolation method. This research focuses on erosion rainfall criteria. A network of 32 ombrographic stations, 1-min temporal resolution rainfall data, 35.6-year period and experimental runoff plots were used. We analysed 8951 rainfalls from ombrographic stations, 100 rainfalls and caused soil losses and runoffs from experimental runoff plots. Main parameter which influenced the number of erosion rainfalls was the precondition AND/OR which determines if conditions of rainfall total (H) have to be fulfilled simultaneously with rainfall intensity (I<sub>15</sub> or I<sub>30</sub>) or not. We proved that if parameters I<sub>15 </sub>> 6.25 mm/15 min AND H > 12.5 mm were fulfilled, then 84.2% of rainfalls caused soil loss > 0.5 t/ha and 73.7% ≥ 1 t/ha. In the case of precondition OR only 44.6% of rainfalls caused soil loss > 0.5 t/ha and 33.9% ≥ 1 t/ha. If the precondition AND was fulfilled, there were on average 75.5 rainfalls, average R factor for each rainfall was 21 MJ/ha·cm/h (without units below in the text, according international unit: 210 MJ/ha·mm/h) and average annual R factor was 45.4. In the case of precondition OR there were on average 279 rainfalls but average R factor for each rainfall was only 9.1 and average annual R factor was 67.4. Therefore if the precondition OR is used, R factor values are overestimated due to a high number of rainfalls with no or very low erosive potential. The resulting overestimated soil losses calculated using USLE/RUSLE subsequently cause an overestimation of financial expenses for erosion-control measures.
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Miguel, Edward y Shanker Satyanath. "Re-examining Economic Shocks and Civil Conflict". American Economic Journal: Applied Economics 3, n.º 4 (1 de octubre de 2011): 228–32. http://dx.doi.org/10.1257/app.3.4.228.
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Miguel, Satyanath, and Ernest Sergenti (2004), henceforth MSS, show that economic growth is negatively related to civil conflict in Africa, using annual rainfall variation as an IV for growth. Antonio Ciccone (2011) argues that thanks to rainfall's mean-reverting nature, rainfall levels are preferable to annual changes. We make three points. First, MSS's findings hold using rainfall levels as instruments. Second, Ciccone (2011) does not provide theoretical justification for preferring rainfall levels. Third, the first-stage relationship between rainfall and growth is weaker after 2000, suggesting that alternative instruments are needed when studying recent conflicts. We highlight the accumulating microeconomic evidence that adverse economic shocks lead to political violence. (JEL D74, E32, O11, O17, O47)
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Mondal, M. Shahjahan, Sara Nowreen y Mostofa Najmus Sakib. "Scale-Dependent Reliability of Projected Rainfalls over Bangladesh with the PRECIS Model". Climate 8, n.º 2 (27 de enero de 2020): 20. http://dx.doi.org/10.3390/cli8020020.
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The regional climate model, Providing REgional Climates for Impact Studies (PRECIS), has been widely used throughout the world to generate climate change projections for impact studies and adaptations. Its recent application in South Asia also includes the projection of rainfall extremes. In spite of its wide application, a stringent validation of the model is yet to be reported. In this study, we assessed the performance of the model in simulating annual, monthly and extreme rainfalls over Bangladesh by using a number of statistical techniques, e.g., pattern (both spatial and temporal) correlation, root mean square difference (RMSD), mean absolute difference (MAD), Student’s t-test for significance, probability density functions, etc. The results indicated that the PRECIS model could capture the overall spatial pattern of mean annual and monthly rainfalls very well. However, the inter-annual variability was poorly simulated by the model. In addition, the model could not capture the rainfall extremes. A spatial aggregation of rainfall data did not improve the reliability of the model as far as variability and extremes are concerned. Therefore, further improvements of the model and/or its driving global climate model are warranted for its practical use in the generation of rainfall scenarios.
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Gu, Zhijia, Detai Feng, Xingwu Duan, Kuifang Gong, Yawen Li y Tianyu Yue. "Spatial and Temporal Patterns of Rainfall Erosivity in the Tibetan Plateau". Water 12, n.º 1 (10 de enero de 2020): 200. http://dx.doi.org/10.3390/w12010200.
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The Tibetan Plateau is influenced by global climate change which results in frequent melting of glaciers and snow, and in heavy rainfalls. These conditions may increase the risk of soil erosion, but prediction is not feasible due to scarcity of rainfall data in the high altitudes of the region. In this study, daily precipitation data from 1 January 1981 to 31 December 2015 were selected for 38 meteorological stations in the Tibetan Plateau, and annual and seasonal rainfall erosivity were calculated for each station. Additionally, we used the Mann–Kendall trend test, Sen’s slope, trend coefficient, and climate tendency rate indicators to detect the temporal variation trend of rainfall erosivity. The results showed that the spatial distribution of rainfall erosivity in the Tibetan Plateau exhibited a significant decreasing trend from southeast to northwest. The average annual rainfall erosivity is 714 MJ·mm·ha−1·h−1, and varies from 61 to 1776 MJ·mm·ha−1·h−1. Rainfall erosivity was mainly concentrated in summer and autumn, accounting for 67.5% and 18.5%, respectively. In addition, annual, spring, and summer rainfall erosivity were increasing, with spring rainfall erosivity highly significant. Temporal and spatial patterns of rainfall erosivity indicated that the risk of soil erosion was relatively high in the Hengduan mountains in the eastern Tibetan Plateau, as well as in the Yarlung Zangbo River Valley and its vicinity.
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Paldor, Nathan. "On the Estimation of Trends in Annual Rainfall Using Paired Gauge Observations". Journal of Applied Meteorology and Climatology 47, n.º 6 (1 de junio de 2008): 1814–18. http://dx.doi.org/10.1175/2007jamc1697.1.
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Abstract A method was recently proposed for evaluating the impact of a perturbation, such as air pollution or urbanization, on the precipitation at a location by calculating the ratio between the precipitation at the perturbed location and that at a location believed to be unperturbed. However, this method may be inappropriate because of the high degree of variability of precipitation at each of the stations. To explore the validity of this approach, noisy annual rainfall records are generated numerically in an upwind, unperturbed station and in a downwind, perturbed station, and the time series of ratio between the annual rainfalls in the two stations is analyzed. The noisy rainfall records are 50 yr long, and the imposed trend for the downwind, perturbed station is −2 mm yr−1 while at the upwind station the variations in annual rainfall are purely noisy. Many pairs of noisy rainfall records are numerically generated (each pair constitutes an experiment), and in every experiment the slope of the linear best fit to the rainfall ratio yields an estimate of the trend of rainfall at the perturbed station. In the absence of noise, the trend of the rainfall ratio is explicitly related to the trend of rainfall at the perturbed station, but the natural rainfall variation at the stations completely masks this explicit relationship. The results show that in some experiments the trend line of the rainfall ratio has the opposite sign to the imposed trend and that in only about one-half of the experiments does the ratio’s trend line lie within ±75% of the imposed trend. Trend estimates within ±25% of the imposed trend are obtained in less than one-quarter of the experiments. This result casts doubt on the generality and validity of using trends of rainfall ratio between two stations to estimate trends of precipitation in one of these stations.
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Soldini, Luciano y Giovanna Darvini. "Extreme rainfall statistics in the Marche region, Italy". Hydrology Research 48, n.º 3 (6 de abril de 2017): 686–700. http://dx.doi.org/10.2166/nh.2017.091.
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A statistical analysis of the rainfalls is carried out for detecting a possible trend in the observed data. The rainfall dataset refers to the historical series collected in the hydrographic basins of the Marche region. On the one hand, the annual maximum daily, hourly and sub-hourly rainfalls have been analysed, on the other hand Climate Change Indices by Expert Team on Climate Change Detection and Indices (ETCCDI) (R1 mm, Rx1day, R20 mm, R95pTOT, PRCPTOT) have been computed to verify an eventual variation of the frequency of the rainfall regime in the Marche region. The time series, selected in the reference period 1951–2013, have been processed by using the non-parametric Mann–Kendall test. The results confirm that most of the series relating to the annual maximum rainfalls do not exhibit any trend. The absence of trend or the presence of negative trend prevail also in the analysis of the ETCCDI indices. The annual average anomalies of the same indices computed with respect to the climatological reference period 1961–1990 are negative since the mid-1980s, but they appear to show an increasing behaviour in the period 2009–2013.
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Saha, Sudip. "Precipitation concentration index (PCI) a tool to evaluate the distribution of Rainfall, Barishal, Bangladesh". International Journal of Advanced Geosciences 8, n.º 2 (30 de septiembre de 2020): 193. http://dx.doi.org/10.14419/ijag.v8i2.31074.
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The present research work reveals the mean annual rainfall of Barishal is 2087.34 mm for the investigated period. The maximum annual rainfall was 3390 mm in the year of 1960 and minimum annual rainfall was recorded as 1277 mm in the year of 1964. The annual rainfall is inversely correlated with time. The maximum monthly rainfall is recorded in the month of July. The amount of annual rainfall is strongly significantly positively correlated with the monthly rainfall of May, June, July, August and September. In Barishal, the value of skewness for all rainfall data are positive that indicate the data are skewed to the right. The positive value of kurtosis of the eleven months of the year (except July) means a peaked distribution and a negative value in the month of July reveals the flat distribution with the same mean and standard deviation. The annual PCI value is inversely proportional to the annual rainfall. The analyses of seasonal precipitation concentration index (SPCI) reveals that the rainfall is uniformly distributed in summer monsoon whereas the winter rainfall shows the dominance of strong irregularity in precipitation distribution.
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Zhang, Peng, He Ping Shu, Jin Zhu Ma, Gang Wang y Li Ming Tian. "The Relationship of Debris Flow Hazards and Rainfall Erosivity in the Bailong River Basin of Southern Gansu Province, China". Advanced Materials Research 1073-1076 (diciembre de 2014): 1614–19. http://dx.doi.org/10.4028/www.scientific.net/amr.1073-1076.1614.
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Rainfall is one of the main factors that drive soil erosion, leading to environmental problems such as increased frequency and severity of debris flows, and ecosystem damage. Rainfall erosivity represents the potential of rainfall to cause soil erosion, and is determined by a combination of rainfall intensity. The spatial and temporal distribution of rainfall erosivity was analyzed to get its relationship with the debris flows in the Bailong River Basin in China's Gansu Province. The mean annual amount of erosive rainfall accounts for 36.0-47.1% of annual precipitation. The annual mean rainfall erosivity amounts to 798.8 MJ mm ha-1 h-1 yr-1 in the Bailong River Basin. A positive correlation between annual precipitation and annual rainfall erosivity was demonstrated at all 18 rainfall stations. However, further research is required to reveal the key factors that explain soil erosion and debris flows.
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Obi, Lawrence Echefulechukwu. "Application of Hydrological Computations in Predicting Rainfall Trends in Imo State of Nigeria". European Journal of Engineering Research and Science 2, n.º 9 (23 de septiembre de 2017): 36. http://dx.doi.org/10.24018/ejers.2017.2.9.367.
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This research employed the empirical method in its approach and workings. Empirical data were collected and various hydrological computations and graphs were engaged through the application of the collected data. The mass curve of rainfall, hyetograph, moving average of annual rainfalls and the computations of recurrence intervals were done by applying the Weibul formular. With computations and its analysis, the recurrent intervals of rainfall magnitudes were determined and rainfall pattern within Imo State were predicted.
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Obi, Lawrence Echefulechukwu. "Application of Hydrological Computations in Predicting Rainfall Trends in Imo State of Nigeria". European Journal of Engineering and Technology Research 2, n.º 9 (23 de septiembre de 2017): 36–41. http://dx.doi.org/10.24018/ejeng.2017.2.9.367.
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This research employed the empirical method in its approach and workings. Empirical data were collected and various hydrological computations and graphs were engaged through the application of the collected data. The mass curve of rainfall, hyetograph, moving average of annual rainfalls and the computations of recurrence intervals were done by applying the Weibul formular. With computations and its analysis, the recurrent intervals of rainfall magnitudes were determined and rainfall pattern within Imo State were predicted.
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SELVARAJ, R. SAMUEL, S. TAMILSELVI y R. GAYATHRI. "Fractal analysis: Annual rainfall in Chennai". MAUSAM 61, n.º 1 (27 de noviembre de 2021): 35–38. http://dx.doi.org/10.54302/mausam.v61i1.774.
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The annual rainfall data of Chennai is analyzed using the Fractal Construction Technique. According to Mandelbrot the dimension of any line including nautical lines may not be Euclidean but Fractional, Mandelbrot, 1982. This fractional dimension leads to a repetitive appearance of any pattern. Climate which is usually periodic by nature can be analyzed through this technique. Efforts are on to search the fractal geometry of climate and to predict its periodicity on different temporal scales. This paper estimates the various parameters like Lyapunov exponent, Maximum Lyapunov characteristic exponent, Lyapunov time, Kaplan-Yorke dimension for the annual rainfall of Chennai.
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Levine, Jonathan M., A. Kathryn McEachern y Clark Cowan. "Rainfall effects on rare annual plants". Journal of Ecology 96, n.º 4 (julio de 2008): 795–806. http://dx.doi.org/10.1111/j.1365-2745.2008.01375.x.
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Agrawal, D. C. "Average Annual Rainfall Over the Globe". Physics Teacher 51, n.º 9 (diciembre de 2013): 540–41. http://dx.doi.org/10.1119/1.4830066.
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Chen, Yi-Ru, Bofu Yu y Graham Jenkins. "Secular variation in rainfall and intensity–frequency–duration curves in Eastern Australia". Journal of Water and Climate Change 4, n.º 3 (18 de abril de 2013): 244–51. http://dx.doi.org/10.2166/wcc.2013.138.
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Rainfall intensity–frequency–duration curves are used extensively for storm runoff estimation. It is generally assumed that rainfall intensity would increase with global warming irrespective of the underlying changes to rainfall. This study analyzed rainfall and temperature from six sites in Eastern Australia. Two non-overlapping 30-year periods with the greatest difference in the mean annual rainfall were selected at each of the six sites to test for significant changes in the mean annual temperature and rainfall. Changes in the mean rainfall intensity for different frequencies of occurrence and storm durations for each site were also analyzed. Temperature has increased at all sites, and significantly at five out of the six sites. The mean annual rainfall has significantly changed between the two non-overlapping periods at the sites with the exception of Cairns (latitude – 16.87° south). The changes in rainfall intensity for longer durations (≥1 h) positively correlate with changes in the mean annual rainfall. There is evidence to suggest that the 6 min rainfall intensity would increase irrespective of the changes in the mean annual rainfall.
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MAPLES, JOSHUA G., B. WADE BRORSEN y JON T. BIERMACHER. "THE RAINFALL INDEX ANNUAL FORAGE PILOT PROGRAM AS A RISK MANAGEMENT TOOL FOR COOL-SEASON FORAGE". Journal of Agricultural and Applied Economics 48, n.º 1 (febrero de 2016): 29–51. http://dx.doi.org/10.1017/aae.2016.3.
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AbstractThe recently implemented Rainfall Index Annual Forage pilot program aims to provide risk coverage for annual forage producers in select states through the use of area rainfall indices as a proxy for yield. This article utilizes unique data from a long-term study of annual ryegrass production with rainfall recorded at the site to determine whether the use of rainfall indices provides adequate coverage for annual forage growers. The rainfall index is highly correlated with actual rainfall. However, it does not provide much yield loss risk protection for our cool-season forage data.
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Gill, S. I., M. A. Naeth, D. S. Chanasyk y V. S. Baron. "Runoff and sediment yield from snowmelt and rainfall as influenced by forage type and grazing intensity". Canadian Journal of Soil Science 78, n.º 4 (1 de noviembre de 1998): 699–706. http://dx.doi.org/10.4141/s97-067.
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Currently, there is interest in Western Canada in extending the grazing season using perennial and annual forages. Of greatest concern is the environmental sustainability of these grazing systems, with emphasis on their ability to withstand erosion. A study to examine the runoff and sediment yields of annual and perennial forages in central Alberta was initiated in 1994. Runoff and sediment yield were quantified under snowmelt and rainfall events for two seasons. Rainfall simulation was used to further examine runoff under growing season conditions. Four forage treatments (two annuals: triticale and a barley/triticale mixture and two perennials: smooth bromegrass and meadow bromegrass) and three grazing intensities (light, medium and heavy) were studied, each replicated four times. Total annual runoff was dominated by snowmelt. Generally runoff volumes, sediment yields, sediment ratios and runoff coefficients were all low. Bare ground increased with increasing grazing intensity and was significantly greater in annuals than perennials for all grazing intensities. Litter biomass decreased with increasing grazing intensity and was generally similar in all species for both years at heavy and medium grazing intensities. Results from the rainfall simulation corroborated those under natural rainfall conditions and generally indicated the sustainability of these grazing systems at this site. Key words: Forages, soil erosion, sustainability, rainfall simulation
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SINGH, VIVEKANAND y ANSHUMAN SINGH. "Variation of temperature and rainfall at Patna". MAUSAM 68, n.º 1 (30 de noviembre de 2021): 161–68. http://dx.doi.org/10.54302/mausam.v68i1.445.
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In this paper, the variation of temperature and rainfall at Patna are analysed using simple non-parametric tests. The trends in the annual maximum and minimum daily temperatures, annual rainfall, annual maximum daily rainfall, number of rainy days in a year, the annual average rainfall per rainy day and the ratio of maximum to average rainfall per rainy day at Patna have been examined. Tends in total monthly rainfall, Highest daily rainfall in a month and number of rainy days in a month have also been determined for every month in a year. The monthly trends of data using simple Mann-Kendall test indicated statistically significant changes in rainfall pattern for the city.
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O’Donnell, Alison J., Michael Renton, Kathryn J. Allen y Pauline F. Grierson. "Tree growth responses to temporal variation in rainfall differ across a continental-scale climatic gradient". PLOS ONE 16, n.º 5 (4 de mayo de 2021): e0249959. http://dx.doi.org/10.1371/journal.pone.0249959.
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Globally, many biomes are being impacted by significant shifts in total annual rainfall as well as increasing variability of rainfall within and among years. Such changes can have potentially large impacts on plant productivity and growth, but remain largely unknown, particularly for much of the Southern Hemisphere. We investigate how growth of the widespread conifer, Callitris columellaris varied with inter-annual variation in the amount, intensity and frequency of rainfall events over the last century and between semi-arid (<500 mm mean annual rainfall) and tropical (>800 mm mean annual rainfall) biomes in Australia. We used linear and polynomial regression models to investigate the strength and shape of the relationships between growth (ring width) and rainfall. At semi-arid sites, growth was strongly and linearly related to rainfall amount, regardless of differences in the seasonality and intensity of rainfall. The linear shape of the relationship indicates that predicted future declines in mean rainfall will have proportional negative impacts on long-term tree growth in semi-arid biomes. In contrast, growth in the tropics showed a weak and asymmetrical (‘concave-down’) response to rainfall amount, where growth was less responsive to changes in rainfall amount at the higher end of the rainfall range (>1250 mm annual rainfall) than at the lower end (<1000 mm annual rainfall). The asymmetric relationship indicates that long-term growth rates of Callitris in the tropics are more sensitive to increased inter-annual variability of rainfall than to changes in the mean amount of rainfall. Our findings are consistent with observations that the responses of vegetation to changes in the mean or variability of rainfall differ between mesic and semi-arid biomes. These results highlight how contrasting growth responses of a widespread species across a hydroclimatic gradient can inform understanding of potential sensitivity of different biomes to climatic variability and change.
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Toni, Abebe Teklu, Andreas Malcherek y Asfaw Kebede Kassa. "Agroclimatic Zone-Based Analysis of Rainfall Variability and Trends in the Wabi Shebele River Basin, Ethiopia". Water 14, n.º 22 (16 de noviembre de 2022): 3699. http://dx.doi.org/10.3390/w14223699.
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The amount and annual distribution of rainfall caused a major socioeconomic and environmental problem where rainfed agriculture is predominant. This study assessed the long-term variability and trends of rainfall in the Wabi Shebele River Basin (WSRB), Ethiopia. The basin was discretized into 9 local agroclimatic zones (ACZ) based on annual rainfall and elevation. The coefficient of variation (CV) was used to check the variability of rainfall while modified Mann-Kendall (MK) and Innovative Trend Analysis (ITA) methods were used to detect rainfall trends. For each ACZ, stations with long-term records and less than 10% of missing data were selected for further analysis. The mean annual rainfall in the basin ranges from 227.2 mm to 1047.4 mm. The study revealed most of the ACZs showed a very high variation in Belg/Spring rainfall (CV% > 30) than Kiremt/Summer and annual rainfall. Seasonal and annual rainfall trend analysis revealed that no uniform trend was detected in all ACZs. However, most of ACZs in the arid and semi-arid areas showed a non-significant decreasing trend in annual rainfall. From seasonal analysis, Belg and Kiremt rainfall showed relatively decreasing and increasing trends respectively. In comparison, a similar result was observed using MK and ITA methods.
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Chen, Yi-Ru, Bofu Yu y Graham Jenkins. "Secular Variation in Rainfall Intensity and Temperature in Eastern Australia". Journal of Hydrometeorology 14, n.º 4 (1 de agosto de 2013): 1356–63. http://dx.doi.org/10.1175/jhm-d-12-0110.1.
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Abstract It is generally assumed that rainfall intensity will increase with temperature increase, irrespective of the underlying changes to the average rainfall. This study documents and investigates long-term trends in rainfall intensities, annual rainfall, and mean maximum and minimum temperatures using the Mann–Kendall trend test for nine sites in eastern Australia. Relationships between rainfall intensities at various durations and 1) annual rainfall and 2) the mean maximum and minimum temperatures were investigated. The results showed that the mean minimum temperature has increased significantly at eight out of the nine sites in eastern Australia. Changes in annual rainfall are likely to be associated with changes in rainfall intensity at the long duration of 48 h. Overall, changes in rainfall intensity at short durations (<1 h) positively correlate with changes in the mean maximum temperature, but there is no significant correlation with the mean minimum temperature and annual rainfall. Additionally, changes in rainfall intensity at longer durations (≥1 h) positively correlate with changes in the mean annual rainfall, but not with either mean maximum or minimum temperatures for the nine sites investigated.
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Indarto, Indarto y Askin Askin. "VARIABILITAS SPASIAL HUJAN DI WILAYAH UPT PSDA DI MALANG". Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering) 6, n.º 3 (28 de marzo de 2018): 171. http://dx.doi.org/10.23960/jtep-l.v6i3.171-180.
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This study show the spatial variabilit of rainfall (monthly and annual) rainfall in the area of technical implementation unit of water resources management (UPT-PSDA) in Malang. Administrative area of UPT PSDA in Malang include Malang regency, Malang city, Batu, Blitar Regency, Tulungagung Regency, and Trenggalek Regency. Daily rainfall data from 88 pluviometers spread around the areas are used as main input. The research procedures consist of : (1) data pre-analysis; (2) the analyses using ESDA tools (Histogram, voronoi, QQ-Plot); (3) interpolation by using IDW method; (4) producing a thematic map; and (5) interpretation. Analysis using the histogram, voronoi–maps and normal QQ-plots tools illustrates more detail the spatial variability of the monthly and annual rainfall around the regions. Interpolation produces a thematic map of mean monthly-rainfall, between 100 – 400 mm/month. The spatial distribution of annual rainfall was illustrated by a thematic show the average-annual-range from 1000 – 4000 mm/year. Keywords: spatial variability, rainfall, ESDA, IDW, monthly, annual rainfall
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Hunt, B. G. "Climatological Extremes of Simulated Annual Mean Rainfall". Journal of Climate 19, n.º 20 (15 de octubre de 2006): 5289–304. http://dx.doi.org/10.1175/jcli3921.1.
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Abstract The Commonwealth Scientific and Industrial Research Organisation (CSIRO) Mark 2 global coupled climatic model has been used to generate a 10 000-yr simulation of “present” climate. The resultant dataset has been used to investigate a number of aspects of extremes associated with annual mean rainfall. Multimillennial time series of normalized rainfall amounts for selected points are used to highlight secular variability, spatial variations, and the differences between pluvial and drought conditions. Global distributions are also presented for selected rainfall characteristics, including the frequency of occurrence of specified rainfall anomalies with annual durations, the frequency of occurrence of 5-yr sequences of specified rainfall anomalies, and the maximum and minimum normalized rainfall amounts attained in the simulation. Such features cannot be obtained from observations because of their limited duration. A case study is also made of a megadrought over the southwestern United States, together with an analysis of the associated causal mechanisms. Given the exclusion of all external forcing from the model, it is concluded that the extreme annual mean rainfall extremes presented in the paper are attributable to stochastic events.
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Nouaceur, Zeineddine y Ovidiu Murărescu. "Rainfall Variability and Trend Analysis of Annual Rainfall in North Africa". International Journal of Atmospheric Sciences 2016 (30 de octubre de 2016): 1–12. http://dx.doi.org/10.1155/2016/7230450.
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The IPCC climate models predict, for the Maghreb countries, lower rainfall and increased aridity. Current observations in the three countries of central Maghreb (Morocco, Algeria, and Tunisia) are not consistent with these predictions. To demonstrate this new trend, a detailed regional analysis of rainfall evolution is conducted. 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 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). 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).
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Zhang, Peng, Gang Wang, Li Ming Tian y Ya Li Zhang. "Spatiotemporal Distribution of Rainfall Erosivity in the Bailong River Basin, Gansu Province". Advanced Materials Research 936 (junio de 2014): 2377–82. http://dx.doi.org/10.4028/www.scientific.net/amr.936.2377.
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Rainfall erosivity is one of the key parameters that determine soil erosion, sediment yield, and water quality, thus its importance has grown in modeling of the environmental effects of climate change. The spatial and temporal distribution of rainfall erosivity in the Bailong River Basin in China's Gansu Province were analyzed. We derived a rainfall erosivity map based on data from 18 meteorological stations in and around the basin using the inverse distance weighting interpolation approach. The annual mean rainfall erosivity within the Bailong River Basin was 798.8 MJ mm ha-1h-1yr-1. The mean annual amount of erosive rainfall accounts for 36.0 to 47.1% of annual precipitation, depending on the station. Rainfall erosivity was greatest from June to September, and rainfall during this period accounts for 77.7% to 84.8% of the total annual rainfall erosivity.
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Liang, Rui, Qiao Zhu, Huan Lian Ren y Hua Jin. "Analysis on Characteristics of the Rainfall-Runoff in Beizhangdian Watershed". Applied Mechanics and Materials 90-93 (septiembre de 2011): 2578–82. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.2578.
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Beizhangdian watershed is a typical semi-dry and semi-humid region, where human activities have little effect on the hydrological cycle. Based on a 30-year hydrological observation data, the precipitation, runoff, and rainfall-runoff relationship were researched by the hydrology statistics analysis methods. The results indicated that the inter-annual change of rainfall-runoff of the watershed is remarkable, the annual distribution of rainfall-runoff is extremely uneven, and rainfall-runoff mainly occurred in flood season (June ~ September). There is a good uniformity between the variation tendency of annual rainfall and annual runoff in time and amount, the correlation coefficient of rainfall and runoff is 0.74, the value of the F-test is 4.23.
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Mazvimavi, D. "Investigating changes over time of annual rainfall in Zimbabwe". Hydrology and Earth System Sciences 14, n.º 12 (22 de diciembre de 2010): 2671–79. http://dx.doi.org/10.5194/hess-14-2671-2010.
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Abstract. There is increasing concern in southern Africa about the possible decline of rainfall as a result of global warming. Some studies concluded that average rainfall in Zimbabwe had declined by 10% or 100 mm during the last 100 years. This paper investigates the validity of the assumption that rainfall is declining in Zimbabwe. Time series of annual rainfall, and total rainfall for (a) the early part of the rainy season, October-November-December (OND), and (b) the mid to end of the rainy season, January-February-March (JFM) are analysed for the presence of trends using the Mann-Kendall test, and for the decline or increase during years with either high or low rainfall using quantile regression analysis. The Pettitt test has also been utilized to examine the possible existence of change or break-points in the rainfall time series. The analysis has been done for 40 rainfall stations with records starting during the 1892–1940 period and ending in 2000, and representative of all the rainfall regions. The Mann-Kendal test did not identify a significant trend at all the 40 stations, and therefore there is no proof that the average rainfall at each of these stations has changed. Quantile regression analysis revealed a decline in annual rainfall less than the tenth percentile at only one station, and increasing of rainfall greater than the ninetieth percentile at another station. All the other stations had no changes over time in both the low and high rainfall at the annual interval. Climate change effects are therefore not yet statistically significant within time series of total seasonal and annual rainfall in Zimbabwe. The general perception about declining rainfall is likely due to the presence of multidecadal variability characterized by bunching of years with above (e.g. 1951–1958, 1973–1980) and below (e.g. 1959–1972, 1982–1994 ) average rainfall.
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Dhak, Dr Sumit M. "Statistical Analysis of Rainfall Variability for Tehsils of Palghar District, Maharashtra State, India". International Journal for Research in Applied Science and Engineering Technology 9, n.º VII (31 de julio de 2021): 2602–18. http://dx.doi.org/10.22214/ijraset.2021.36931.
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A detailed statistical analysis of monthly, seasonal and annual rainfall for Tehsils of Palghar district were carried out using 22 years (1998-2019) daily rainfall data taken from Department of Agriculture, Maharashtra State. The mean, standard deviation and coefficient of variation for monthly, seasonal and annual rainfall were computed for tehsils of Palghar districts. The month of July received maximum monthly mean rainfall for all years (1998 to 2019) in tehsils of Palghar district. The result showed that monthly mean rainfall in month of July was maximum at Jawhar (1147.1 mm) followed by Vikramgad (1071.9 mm), Talasari (1014.3 mm), Vasai (1009.9 mm), Wada (998.5 mm), Mokhada (949.6 mm), Palghar (948.7 mm) and Dahanu (841.6) with contributes 40.4 %, 39.1 %, 38.5 %, 35.4 %, 37.3 %, 37.3 %, 36.9 % and 36.3 % of the annual mean rainfall (1998 to 2019) respectively. The result showed that contribution of rainfall during Monsoon season ranges from 95.5 % to 97.0 % of the annual total rainfall for tehsils of Palghar District. The result showed that average annual rainfall (1998 to 2019) of Vasai, Jawhar, Vikramgad, Wada, Talasari, Palghar, Mokhada and Dahanu were 2855.9 mm, 2839.1 mm, 2738.9 mm, 2674.0 mm, 2633.3 mm, 2570.8 mm, 2543.6 mm and 2318.5 mm respectively.
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Eddenjal, Ali Salem. "Spatio Temporal Variability of Rainfall Across Western Libya from 1979 to 2009". Current Environmental Management 6, n.º 3 (7 de enero de 2020): 235–44. http://dx.doi.org/10.2174/2212717806666191022175547.
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Aims: To understand the links between climate variability and hydrology in western Libya. Background: This study represents the first comprehensive assessment of rainfall variability in western Libya at a regional scale. Objective: To assess temporal and spatial variability of rainfall in western Libya, based on data (1979-2009) from 16 rain gauges. Methods: The non-parametric Mann-Kendall method and Sen’s slop estimator were used to define changes in rainfall series and their statistical significance. Results: Coastal and mountainous time series showed decreasing trends at the annual, autumn, and spring scales, with very few exceptions. Notably, winter showed increasing trends, with the significant values of 1.94 and 0.88 mm/year at Sirt and Nalut, respectively. Desert stations showed increasing trends, especially at the annual scale, with the greatest significant increase on the order of 1.19 mm/year in Ghadames. For the regional rainfall trend analysis, annual, spring and autumn rainfalls decreased in the coastal and mountainous zones, with the highest significant decrease of 1.94 mm/year. Again, winter rainfall showed increasing trend over the whole study domain. Conclusion: Although most time series showed a tendency towards more drier conditions, most of the detected trends were statistically non-significant. This study will provide guidance for policy makers in their future planning to mitigate the impact of drought.
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Fanai, Liansangpuii, K. N. Singh, R. Singh, R. M. Singh y D. Khalkho. "Statistical and temporal trends analysis of rainfall in Bundelkhand region, Central India". Environment Conservation Journal 23, n.º 1&2 (11 de febrero de 2022): 131–42. http://dx.doi.org/10.36953/ecj.021812-2119.
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Three timescale i.e. monthly, seasonal and annual rainfall data of Bundelkhand region, Central India, was analyzed for 40 years (1981-2020). The annual mean average rainfall for the region ranges between 657.7 mm and 1146.4 mm for the studied period with the month August receiving the highest amount of rainfall. The region receives about 90 % of its annual rainfall during South West Monsoon period i.e. from June to September. Temporal trend of rainfall for different timescale was analysed using nonparametric Mann-Kendall test and Sen’s slope estimator. Increasing and decreasing trend were found for the three timescale in which the study was carried out. Annual rainfall trend of Bundelkhand region is found to follow decreasing trend except for Sagar district. A decreasing South West Monsoon rainfall trend was also observed in 11 districts of Bundelkhand region.
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VISHWANATH, G. V. VENKATARAMANA y N. PRABHAKARAN. "STUDY OF RAINFALL DISTRIBUTION PATTERN AND ITS VARIABILITY IN BIDAR REGION, KARNATAKA, INDIA". Asian Journal of Microbiology, Biotechnology & Environmental Sciences 24, n.º 04 (2022): 728–34. http://dx.doi.org/10.53550/ajmbes.2022.v24i04.018.
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A case study has been done to study the rainfall distribution pattern and its variability for the selection of crops and cropping pattern of Bidar region, Karnataka with a predominant pigeon pea and sugarcane cropping systems. The study revealed that the overall mean annual rainfall of Aurad was 846 mm, which was distributed as 673.7 mm, 101.6 mm, 60.2 mm and 10.7 mm in monsoon, post monsoon, summer and winter respectively. The average annual rainfall of Bhalki was 874.7 mm with average rainy days of 51 days. The mean annual rainfall of Humnabad is 797 mm with 27 per cent variability spread over 50 mean rainy days. The analysis of rainfall data indicate that the average annual rainfall for the Basavakalyan was 759 mm spread over with a mean rainy days of 49.9 days. The mean annual rainfall for Bidar is 937.3 mm with coefficient of variation of 22.2 per cent indicated that the annual rainfall was more or less stable over the years. Within the rainy season, August was the highest rainfall contributing month (21.3 per cent) followed by July (19.9 per cent). Rainfall during monsoon season and its variability govern the cropping system of Bidar. There is an ample scope for rain water harvesting from July to September which can be utilized as crop saving irrigation as well as per sowing irrigation for succeeding rabi crops which are generally sown on residual soil moisture.
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Mazvimavi, D. "Investigating possible changes of extreme annual rainfall in Zimbabwe". Hydrology and Earth System Sciences Discussions 5, n.º 4 (10 de julio de 2008): 1765–85. http://dx.doi.org/10.5194/hessd-5-1765-2008.
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Abstract. There is increasing concern about the perceived decline in rainfall which is sometimes attributed to global warming. Some studies have concluded that average rainfall in Zimbabwe has declined by 10% or 100 mm/yr during the last 100 yrs. This paper investigates the validity of the assumption that rainfall is declining in Zimbabwe. Time series of annual rainfall, and total rainfall for a) the early party of the rainy season, October-November-December (OND), and b) the mid to end of the rainy season, January-February-March (JFM) are analysed for the presence of trends using the Mann-Kendall test, and changes in extreme rainfall using quantile regression analysis. The analysis has been done for 40 rainfall stations with records starting during the 1892–1940 period and ending in 2000, and representative of the major rainfall regions. The Mann-Kendal test did not identify a significant trend at all the 40 stations, and therefore there is no proof that the average rainfall at each of these stations has changed. Quantile regression analysis revealed a decline in annual rainfall less than the tenth percentile at only one station, and increasing rainfall for rainfall greater than the ninetieth percentile at another station. All the other stations revealed no changes over time in both the extreme low and high rainfall at the annual interval. Therefore, there is no evidence that the frequency and severity of droughts has changed during the 1892 to 2000 period. The general perception about declining rainfall is likely shaped by a comparison of the recent drought years (1980's–1990's) to recent wet periods (1970's). There have however been periods with similar dry years beyond the recallable memory, e.g. 1926–1936, 1940's. Crop failures and livestock losses attributed to declining rainfall are most likely due to poor agricultural practices such as production of crops in unsuitable climatic regions, degradation of rangelands partly due to increasing livestock populations. Rainfall in Zimbabwe has high inter-annual variability, and currently any change due to global warming is not yet statistically detectable. The annual renewal rate of water resources from rainfall has therefore not changed, and an adaptive water resources management approach is called to overcome problems arising from increasing water demand, and variability of available water resources.
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Yoo, Chulsang, Minkyu Park, Hyeon Jun Kim y Changhyun Jun. "Comparison of annual maximum rainfall events of modern rain gauge data (1961–2010) and Chukwooki data (1777–1910) in Seoul, Korea". Journal of Water and Climate Change 9, n.º 1 (6 de octubre de 2017): 58–73. http://dx.doi.org/10.2166/wcc.2017.110.
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Abstract In this study, the annual maximum rainfall event series were constructed and compared for both the modern flip-bucket type rainfall data, collected since 1961 (the modern data), and the old Chukwooki rainfall data, collected from 1777 to 1910 (the Chukwooki data). First, independent rainfall events were derived, by applying the same rainfall threshold of 2 mm and data collection time interval of 2 hours, to both the Chukwooki and the modern data. Annual maximum rainfall event series were then constructed, by applying Freund's bivariate exponential distribution annually. Finally, bivariate frequency analysis was done for the annual maximum rainfall event series constructed, by applying the bivariate logistic model to evaluate and quantify their characteristics. The results are in summary: (1) characteristics of the Chukwooki rainfall events and modern rainfall events are very similar to each other; (2) the annual maximum rainfall events of modern data are slightly larger than those of the Chukwooki data. The total rainfall depth per rainfall event for any given return period is thus estimated to be a little higher for the modern data than that of the Chukwooki data. However, based on the findings in this study, it could not be concluded that the rainfall characteristics have significantly changed during the last 200 years.
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Whiting, J. P., M. F. Lambert y A. V. Metcalfe. "Modelling persistence in annual Australia point rainfall". Hydrology and Earth System Sciences 7, n.º 2 (30 de abril de 2003): 197–211. http://dx.doi.org/10.5194/hess-7-197-2003.
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Abstract. Annual rainfall time series for Sydney from 1859 to 1999 is analysed. Clear evidence of nonstationarity is presented, but substantial evidence for persistence or hidden states is more elusive. A test of the hypothesis that a hidden state Markov model reduces to a mixture distribution is presented. There is strong evidence of a correlation between the annual rainfall and climate indices. Strong evidence of persistence of one of these indices, the Pacific Decadal Oscillation (PDO), is presented together with a demonstration that this is better modelled by fractional differencing than by a hidden state Markov model. It is shown that conditioning the logarithm of rainfall on PDO, the Southern Oscillation index (SOI), and their interaction provides realistic simulation of rainfall that matches observed statistics. Similar simulation models are presented for Brisbane, Melbourne and Perth. Keywords: Hydrological persistence,hidden state Markov models, fractional differencing, PDO, SOI, Australian rainfall
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Lompi, Marco, Paolo Tamagnone, Tommaso Pacetti, Renato Morbidelli y Enrica Caporali. "Impacts of Rainfall Data Aggregation Time on Pluvial Flood Hazard in Urban Watersheds". Water 14, n.º 4 (11 de febrero de 2022): 544. http://dx.doi.org/10.3390/w14040544.
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Pluvial floods occur when heavy rainstorms cause the surcharge of the sewer network drainage, representing one of the most impacting natural hazard in urban watersheds. Pluvial flood hazard is usually assessed considering the effect of annual maxima rainfall of short duration, comparable with the typical concentration times of small urban watersheds. However, short duration annual maxima can be affected by an error of underestimation due to the time resolution as well as the aggregation time of the rainfall time series. This study aims at determining the impact of rainfall data aggregation on pluvial flood hazard assessment. Tuscany region (Central Italy) is selected as a case study to perform the assessment of the annual maxima rainfall underestimation error, since the entire region has the same temporal aggregation of rainfall data. Pluvial flood hazard is then evaluated for an urban watershed in the city of Florence (Tuscany) comparing the results obtained using observed (uncorrected) and corrected annual maxima rainfall as meteorological forcing. The results show how the design of rainfall events with a duration of 30 min or shorter is significantly affected by the temporal aggregation, highlighting the importance of correcting annual maxima rainfall for a proper pluvial flood hazard evaluation.
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Barron, O. V., R. S. Crosbie, W. R. Dawes, S. P. Charles, T. Pickett y M. J. Donn. "Climatic controls on diffuse groundwater recharge across Australia". Hydrology and Earth System Sciences 16, n.º 12 (4 de diciembre de 2012): 4557–70. http://dx.doi.org/10.5194/hess-16-4557-2012.
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Abstract. Reviews of field studies of groundwater recharge have attempted to investigate how climate characteristics control recharge, but due to a lack of data have not been able to draw any strong conclusions beyond that rainfall is the major determinant. This study has used numerical modelling for a range of Köppen-Geiger climate types (tropical, arid and temperate) to investigate the effect of climate variables on recharge for different soil and vegetation types. For the majority of climate types, the correlation between the modelled recharge and total annual rainfall is weaker than the correlation between recharge and the annual rainfall parameters reflecting rainfall intensity. Under similar soil and vegetation conditions for the same annual rainfall, annual recharge in regions with winter-dominated rainfall is greater than in regions with summer-dominated rainfall. The importance of climate parameters other than rainfall in recharge estimation is highest in the tropical climate type. Mean annual values of solar radiation and vapour pressure deficit show a greater importance in recharge estimation than mean annual values of the daily mean temperature. Climate parameters have the lowest relative importance in recharge estimation in the arid climate type (with cold winters) and the temperate climate type. For 75% of all soil, vegetation and climate types investigated, recharge elasticity varies between 2 and 4 indicating a 20% to 40% change in recharge for a 10% change in annual rainfall. Understanding how climate controls recharge under the observed historical climate allows more informed choices of analogue sites if they are to be used for climate change impact assessments.
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Pinheiro, Antonio G., Thais E. M. dos S. Souza, Suzana M. G. L. Montenegro, Abelardo A. de A. Montenegro y Sérgio M. S. Guerra. "Rainfall pattern and erosion potential in the physiographic regions of the state of Pernambuco, Brazil". Revista Brasileira de Engenharia Agrícola e Ambiental 22, n.º 12 (diciembre de 2018): 849–53. http://dx.doi.org/10.1590/1807-1929/agriambi.v22n12p849-853.
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ABSTRACT The objective of the present study was to characterize the spatial and temporal (2000-2015) rainfall pattern variability and erosive potential in the different physiographic regions of the state of Pernambuco, Brazil. Rainfall data series (3 to 12 years) from 25 weather stations of the state were analyzed. Erosive rainfall events (more than 10 mm depth) were considered to evaluate the annual erosivity index, monthly erosivity index (EI30), rainfall erosivity factor (R), and rainfall pattern. The inverse distance weighting (IDW) - inverse of the square of the distance - was used to create spatial interpolation and develop maps. The rainfall data from the weather stations showed average annual rainfall of 827 mm and average erosivity of 4,784 MJ mm ha-1 h-1. The Metropolitan region of Pernambuco presented the highest rainfall erosivity index, with annual average of 9,704 MJ mm ha-1 h-1; and the Sertão do São Francisco region had the lowest, with annual average of 4,902 MJ mm ha-1 h-1. The state of Pernambuco presented advanced (42%), intermediate (38%), and delayed (20%) rainfall patterns.
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SINGH, VARTIKA y PRAMENDRA DEV. "50 year rainfall data analysis and future trend in Saharanpur region". MAUSAM 63, n.º 1 (31 de diciembre de 2021): 55–64. http://dx.doi.org/10.54302/mausam.v63i1.1455.
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The environmental implications of rainfall pattern in replenishment of ground water system of Saharanpur region, located in western Uttar Pradesh, have been discussed. The mathematical analysis of rainfall dissimilarity of Saharanpur region for a period of 50 year (1959 to 2008) display a quite good range from 497.70 to 4357.5 mm with an annual average rainfall value of 1209.8 mm. The positive trend of departure from the computer value of average annual rainfall exhibits appropriate periods for recharge of ground water reservoir. The recorded data of annual rainfall during the last 3 year reveal values below the calculated annual average rainfall, pointing out negative trend. The statistical analysis of rainfall data involves computations of various statistical parameters, which also support the negative trend of rainfall. The prediction of expected future rainfall trend for a period up to 2018 has been made, which indicates a negative trend. The proposal have been incorporated to implement a plan for augmentation of ground water resource and also to develop possibilities of rainwater harvesting.
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Barron, O. V., R. S. Crosbie, D. Pollock, W. R. Dawes, S. P. Charles, T. Pickett y M. Donn. "Climatic controls on diffuse groundwater recharge across Australia". Hydrology and Earth System Sciences Discussions 9, n.º 5 (9 de mayo de 2012): 6023–62. http://dx.doi.org/10.5194/hessd-9-6023-2012.
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Abstract. Reviews of field studies of groundwater recharge have attempted to investigate how climate characteristics control recharge, but due to a lack of data have not been able to draw any strong conclusions beyond that rainfall is the major determinant. This study has used numerical modeling for a range of Köppen-Geiger climate types (tropical, arid and temperate) to investigate the effect of climate variables on recharge for different soil and vegetation types. For the majority of climate types the total annual rainfall had a weaker correlation with recharge than the rainfall parameters reflecting rainfall intensity. In regions with winter-dominated rainfall, annual recharge under the same annual rainfall, soils and vegetation conditions is greater than in regions with summer-dominated rainfall. The relative importance of climate parameters other than rainfall is higher for recharge under annual vegetation, but overall is highest in the tropical climate type. Solar radiation and vapour pressure deficit show a greater relative importance than mean annual daily mean temperature. Climate parameters have lowest relative importance in the arid climate type (with cold winters) and the temperate climate type. For 75% of all considered cases of soil, vegetation and climate types recharge elasticity varies between 2 and 4, indicating a 20% to 40% change in recharge for a 10% change in annual rainfall Understanding how climate controls recharge under the observed historical climate allows more informed choices of analogue sites if they are to be used for climate change impact assessments.
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Kokilavani, S., R. Selvi, S. Panneerselvam y Ga Dheebakaran. "Trend Analysis of Rainfall Variability in Western Agro Climatic Zone of Tamil Nadu". Current World Environment 12, n.º 1 (25 de abril de 2017): 181–87. http://dx.doi.org/10.12944/cwe.12.1.22.
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An analytical examination was done to work out the unevenness in point location and time to time variability in rainfall at Coimbatore and Erode district of Western agro climatic zone of Tamil Nadu (India) for 100 years (1916-2015). Simple descriptive statistics along with Co-efficient of Variation (CV) were worked to understand the rainfall variability. The long term mean seasonal and annual rainfall analysis showed that South West Monsoon (SWM) rainfall observed was (176.9 mm) & (257.9 mm) and North East Monsoon (NEM) of (336.9 mm) & (323.3 mm) and annual rainfall of (674.8 mm) & (764.4 mm) at Coimbatore and Erode respectively. The CV for seasonal and annual rainfall showed high dependability status by recording appropriate threshold level of CV for seasonal and annual rainfall. The time series rainfall data for 100 years were divided into ten year period and the correlation was carried out for the SWM and NEM using Spearman’s rank-order correlation. The results indicated the correlation between two monsoons for Coimbatore (0.14) and for erode (0.07) which indicates that there was less relation between SWM and NEM. Major emphasis was given to analyse annual and seasonal (SWM and NEM) rainfall time sequence over an extensive time gap to identify probable trend and to measure their implication. For Coimbatore and Erode districts, in both the monsoon seasons and annual analysis revealed an increasing trend for long term (100 years-1916-2015) period.
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Martins, Sérgio Gualberto, Junior Cesar Avanzi, Marx Leandro Naves Silva, Nilton Curi, Lloyd Darrell Norton y Sebastião Fonseca. "Rainfall erosivity and rainfall return period in the experimental watershed of Aracruz, in the coastal plain of Espirito Santo, Brazil". Revista Brasileira de Ciência do Solo 34, n.º 3 (junio de 2010): 999–1004. http://dx.doi.org/10.1590/s0100-06832010000300042.
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Knowledge on the factors influencing water erosion is fundamental for the choice of the best land use practices. Rainfall, expressed by rainfall erosivity, is one of the most important factors of water erosion. The objective of this study was to determine rainfall erosivity and the return period of rainfall in the Coastal Plains region, near Aracruz, a town in the state of Espírito Santo, Brazil, based on available data. Rainfall erosivity was calculated based on historic rainfall data, collected from January 1998 to July 2004 at 5 min intervals, by automatic weather stations of the Aracruz Cellulose S.A company. A linear regression with individual rainfall and erosivity data was fit to obtain an equation that allowed data extrapolation to calculate individual erosivity for a 30-year period. Based on this data the annual average rainfall erosivity in Aracruz was 8,536 MJ mm ha-1 h-1 yr-1. Of the total annual rainfall erosivity 85 % was observed in the most critical period October to March. Annual erosive rains accounted for 38 % of the events causing erosion, although the runoff volume represented 88 % of the total. The annual average rainfall erosivity return period was estimated to be 3.4 years.