Precipitation Trends over Time Using Mann-Kendall and Spearman’s rho Tests in Swat River Basin, Pakistan

Ahmad, Ijaz; De-shan, Tang; Wang, Tianfang; Wang, Mei; Wagan, Bakhtawar

doi:10.1155/2015/431860

Cited by 343 publications

(236 citation statements)

References 41 publications

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“…There are many methods to detect the significant trend of the considered meteorological elements in time series of the selected stations, the Mann-Kendall and Spearman's Rho test are most widely used. Many theses have discussed the difference between the Mann-Kendall and Spearman's Rho test [36][37][38], the results show a similar performance of these two methods. In this study we used the M-K method to detect the significant trend and Sen's method to detect trend magnitudes, which were suggested by the World Meteorological Organization [39].…”

Section: Mann-kendall Trend Test and Slop Estimatormentioning

confidence: 78%

Spatio-Temporal Analysis of Meteorological Elements in the North China District of China during 1960–2015

Yang

Yin

et al. 2018

Water

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Abstract:The North China District (NCD) is one of the main grain production regions in China. The double cropping system of irrigation has been leading to the groundwater table decline at the speed of 1-2 m per year. Climate change leads to uncertainty surrounding the future of the NCD agricultural system, which will have great effects on crop yields and crop water demands. In this research, the Meteorological dataset from 54 weather station sites over the period 1960-2015 were collected to quantify the long-term spatial and temporal trends of meteorological data, including daily minimum temperature (T min ), maximum temperature (T max ), precipitation, solar radiation, reference evapotranspiration (ET 0 ), and aridity index (AI). The results show that the long-term wheat and maize growing season and annual average air temperatures (T min and T max ) showed strong north to south increasing trends throughout the NCD. The average annual precipitation was 632.9 mm across the NCD, more than 70% of which was concentrated in the maize growing season. The regional average annual ET 0 was 1026.1 mm, which was 531.2 and 497.4 mm for the wheat and maize growing season, respectively. The regional precipitation decreased from northwest to southeast in each growing season and annual timescale. The funnel areas have lower precipitation and higher ET 0 than the regional average, which may lead to the mining of the groundwater funnel area. The regional average annual AI is 0.63, which lies in the humid class. For temporal analysis, the regional average trends in annual T min , T max , solar radiation, ET 0 , precipitation, and AI were 0.37 • C/10a, 0.15 • C/10a, −0.28 MJ/day/m 2 /10a, −2.98 mm/10a, −12.04 mm/10a, and 0.005/10a, respectively. The increasing trend of temperature and the decreasing trend of solar radiation may have a negative effect on the regional food security. The funnel area AI showed a significant increasing trend for the winter wheat growing season and a decreasing trend for maize, which indicated that more irrigation will be needed for the maize growing season and the winter fallow policy may lead to the increasing trend precipitation being wasted. Analyzing the growing season and the annual meteorological elements of the spatiotemporal trends can help us better understand the influence of climate change on the natural resources and agricultural development in both the past and the future, and will provide us with invaluable information for the modification of cropping patterns to protect the regional and national water and food security.

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Section: Mann-kendall Trend Test and Slop Estimatormentioning

confidence: 78%

Spatio-Temporal Analysis of Meteorological Elements in the North China District of China during 1960–2015

Yang

Yin

et al. 2018

Water

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“…This showed that two weather systems influence the precipitation in the Astore sub-basin of the UIB: the Indian summer monsoon (ISM) that bring liquid precipitation during summer [55], and the western disturbances (WDs) that bring solid precipitation during winter and early spring [8,49]. The average annual temperature in the whole Astore basin was found to be significantly (p ≤ 0.05) increasing with Z = 1.75 and the Sen's slope value of 0.041 • C·year −1 and the same temperature trend was observed in the summer (Z = 0.66, Sen's slope = 0.034 • C·year −1 ) and winter (Z = 0.77, Sen's slope = 0.064 • C·year −1 ) seasons.…”

Section: Astore Sub-basinmentioning

confidence: 99%

Investigating Snow Cover and Hydrometeorological Trends in Contrasting Hydrological Regimes of the Upper Indus Basin

2018

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Abstract:The Upper Indus basin (UIB) is characterized by contrasting hydrometeorological behaviors; therefore, it has become pertinent to understand hydrometeorological trends at the sub-watershed level. Many studies have investigated the snow cover and hydrometeorological modeling at basin level but none have reported the spatial variability of trends and their magnitude at a sub-basin level. This study was conducted to analyze the trends in the contrasting hydrological regimes of the snow and glacier-fed river catchments of the Hunza and Astore sub-basins of the UIB. Mann-Kendall and Sen's slope methods were used to study the main trends and their magnitude using MODIS snow cover information (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015) and hydrometeorological data. The results showed that in the Hunza basin, the river discharge and temperature were significantly (p ≤ 0.05) decreased with a Sen's slope value of −2.541 m 3 ·s −1 ·year −1 and −0.034 • C·year −1 , respectively, while precipitation data showed a non-significant (p ≥ 0.05) increasing trend with a Sen's slope value of 0.023 mm·year −1 . In the Astore basin, the river discharge and precipitation are increasing significantly (p ≤ 0.05) with a Sen's slope value of 1.039 m 3 ·s −1 ·year −1 and 0.192 mm·year −1 , respectively. The snow cover analysis results suggest that the Western Himalayas (the Astore basin) had a stable trend with a Sen's slope of 0.07% year −1 and the Central Karakoram region (the Hunza River basin) shows a slightly increasing trend with a Sen's slope of 0.394% year −1 . Based on the results of this study it can be concluded that since both sub-basins are influenced by different climatological systems (monsoon and westerly), the results of those studies that treat the Upper Indus basin as one unit in hydrometeorological modeling should be used with caution. Furthermore, it is suggested that similar studies at the sub-basin level of the UIB will help in a better understanding of the Karakoram anomaly.

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“…A forma de cálculo de Z está mostrada em diversos textos (p. ex., Ahmad et al, 2015). Sinal positivo (negativo) de Z indica tendência de crescimento (redução).…”

Section: Análise De Tendênciaunclassified

Eventos de Precipitação Extrema na Região do Centro de Lançamento de Alcântara

Oyama

Oliveira

2016

Rev. bras. meteorol.

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Resumo Totais diários de precipitação foram utilizados para identificar os eventos de Precipitação Extrema (PE) na região do Centro de Lançamento de Alcântara (CLA) para o período de set-1984 a ago-2014 (30 anos). Adotando o 99° percentil dos totais diários (44 mm d-1) como limiar de PE, foram identificados 104 eventos no período. O ciclo anual da frequência de eventos e das excedências foi muito semelhante ao ciclo anual da precipitação, com máximo (mínimo) no trimestre MAM (SON). Utilizando as séries de duração parcial, os máximos anuais de total diário (definindo ano hidrológico como os 12 meses a partir de setembro) puderam ser modelados estatisticamente como uma distribuição de Gumbel. A precipitação de 1 dia com tempo de retorno de 100 anos seria de 115 mm, valor inferior aos encontrados na literatura para localidades pertencentes à região do CLA. Para o bimestre de março e abril, que concentrou a maior frequência de eventos, a variabilidade interanual da frequência esteve correlacionada positiva e significativamente (R = +0,44) com o total de precipitação, e a correlação parcial com outros fatores (índice Niño 3, gradiente inter-hemisférico de temperatura da superfície do mar do Atlântico e vento em 925 hPa sobre a região do CLA) não foi significativa. Os dias de PE no bimestre diferenciaram-se dos demais com totais elevados por apresentarem maior número de horas do dia com chuva (14 ± 4 h) e maiores totais horários (p. ex., total horário máximo = 23 ± 9 mm h-1). No bimestre de março e abril de 1996, quando houve a maior frequência de eventos (5 eventos), os dias de PE caracterizaram-se pela ocorrência de atividade convectiva intensa sobre duas grandes áreas: uma zonalmente alongada cobrindo a costa norte do Brasil, e outra cobrindo os Estados de Santa Catarina e Paraná.

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Precipitation Trends over Time Using Mann-Kendall and Spearman’s rho Tests in Swat River Basin, Pakistan

Cited by 343 publications

References 41 publications

Spatio-Temporal Analysis of Meteorological Elements in the North China District of China during 1960–2015

Spatio-Temporal Analysis of Meteorological Elements in the North China District of China during 1960–2015

Investigating Snow Cover and Hydrometeorological Trends in Contrasting Hydrological Regimes of the Upper Indus Basin

Eventos de Precipitação Extrema na Região do Centro de Lançamento de Alcântara

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