Spatio-Temporal Trend Analysis of Rainfall and Temperature Extremes in the Vea Catchment, Ghana

This study examined the trends in annual rainfall and temperature extremes over the Vea catchment for the period 1985–2016, using quality-controlled stations and a high resolution (5 km) Climate Hazards Group InfraRed Precipitation with Station (CHIRPS) data. The CHIRPS gridded precipitation data’s ability in reproducing the climatology of the catchment was evaluated. The extreme rainfall and temperature indices were computed using a RClimdex package by considering seventeen (17) climate change indices from the Expert Team on Climate Change Detection Monitoring Indices (ETCCDMI). Trend detection and quantification in the rainfall (frequency and intensity) and temperature extreme indices were analyzed using the non-parametric Mann–Kendall (MK) test and Sen’s slope estimator. The results show a very high seasonal correlation coefficient (r = 0.99), Nash–Sutcliff efficiency (0.98) and percentage bias (4.4% and −8.1%) between the stations and the gridded data. An investigation of dry and wet years using Standardized Anomaly Index shows 45.5% frequency of drier than normal periods compared to 54.5% wetter than normal periods in the catchment with 1999 and 2003 been extremely wet years while the year 1990 and 2013 were extremely dry. The intensity and magnitude of extreme rainfall indices show a decreasing trend for more than 78% of the rainfall locations while positive trends were observed in the frequency of extreme rainfall indices (R10mm, R20mm, and CDD) with the exception of consecutive wet days (CWD) that shows a decreasing trend. A general warming trend over the catchment was observed through the increase in the annual number of warm days (TX90p), warm nights (TN90p) and warm spells (WSDI). The spatial distribution analysis shows a high frequency and intensity of extremes rainfall indices in the south of the catchment compared to the middle and northern of part of the catchment, while temperature extremes were uniformly distributed over the catchment.

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Analysis of Daily Rainfall and Spatiotemporal Trends of Extreme Rainfall at Paraná Slope of the Itararé Watershed, Brazil

Revista Brasileira de Meteorologia ◽

10.1590/0102-7786352025 ◽

2020 ◽

Vol 35 (2) ◽

pp. 357-374

Author(s):

Paulo Miguel de Bodas Terassi ◽

José Francisco de Oliveira Júnior ◽

Givanildo de Gois ◽

Bruno Serafini Sobral ◽

Emerson Galvani ◽

...

Keyword(s):

Daily Rainfall ◽

Extreme Rainfall ◽

High Volume ◽

Annual Rainfall ◽

Annual Number ◽

Subtropical Climate ◽

Homogeneous Groups ◽

The North ◽

Spatiotemporal Trends ◽

Mk Test

Abstract The knowledge of intensity and frequency of rainfall allows establishing predictive measures to minimize impacts caused by high volume of rainfall totals in a region. Therefore, the objective is to evaluate daily rainfall for Paraná slope of the Itararé watershed (PSIW) and to verify the spatiotemporal trend of intense and extreme daily rainfall. Rainfall data from 14 stations collected from 1976 to 2012 were used with less than 4% of data faults. Multivariate analysis based on cluster analysis technique (CA) was used applying the Euclidean distance for the identification of homogeneous groups, and the quantiles technique to classify daily rainfall. The Mann-Kendall (MK) test was used to identify trends for annual rainfall totals, annual number of rainy days (ANRD) and for the occurrence of intense (R95p) and extreme (R99p) rainfall. The CA technique identified three rainfall groups (HG I, II and III). Given the latitudinal position of the area, rainfall at the southern sector is characterized by its greater similarities with the subtropical climate, whereas in the North sector there is a consistent reduction of rainfall totals in autumn and, especially, during winter months, which are characteristic of the tropical climate. The MK test identified the downward trend of ANRD, with greater significance for the south-centered sectors of the basin. The observed trends for the intense (R95p) and extreme (R99p) daily rainfall show the predominance of reduction for the Southwest and central sector, followed by a significant increase in the Southeast and North sectors of the PSIW.

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Spatio-temporal Trend Detection of Rainfall for Climate Change Assessment in Ahmedabad-Gandhinagar District of Gujarat State, India

Journal of Climate Change ◽

10.3233/jcc210006 ◽

2021 ◽

Vol 7 (1) ◽

pp. 69-78

Author(s):

Geeta S. Joshi ◽

Payal Makhasana

Keyword(s):

Climate Change ◽

Rain Gauge ◽

The State ◽

Monthly Rainfall ◽

Trend Detection ◽

Annual Rainfall ◽

Sen’S Slope Estimator ◽

Sen’S Slope ◽

Mk Test ◽

Slope Estimator

The present research aims to assess the historical change in rainfall patterns with the changing climate in the Ahmedabad-Gandhinagar district in the state of Gujarat in India. The Mann-Kendall (MK) test along with Sen’s slope estimator have been used for detecting the trend of rainfall data series. The trend of annual rainfall is carried out for – (1) six rain gauge stations established by the State Water Data Center (SWDC) and (2) 11 grid data available from the National Center for Environmental Prediction-Climate Forecast System Reanalysis (NCEP-CFSR) for 35 years starting from 1979 to 2013. Results obtained from these two data sets for the trend detection were found consistent. Furthermore, the analyses of annual and monthly rainfall using MK test and Sen’s slope estimator at six rain gauge stations are carried out in three time periods i.e. 1974-1987, 1988-2001 and 2002-2016. The inverse distance weighted (IDW) method of interpolation is used for the results obtained from the spatial distribution of the temporal rainfall trend for interpolating the station value over the study area. Annual rainfall for data length of 1979 to 2013 shows an increasing trend. The trend of annual and monthly rainfall for July and September shows a positive trend for the span 2002-2016. This study would be useful to the water resource department and policymakers for climate change adaptation in the study area.

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Long-term trends of climate change and its impact on crop growing season on Montreal Island

Journal of Water and Climate Change ◽

10.2166/wcc.2016.139 ◽

2016 ◽

Vol 8 (1) ◽

pp. 78-88

Author(s):

Erika Bouchard ◽

Zhiming Qi

Keyword(s):

Climate Change ◽

Daily Rainfall ◽

Growing Season ◽

Annual Rainfall ◽

Climate Trends ◽

Growing Season Length ◽

Mk Test ◽

Long Term Trends ◽

Increasing Trends

Long-term trends in air temperature and precipitation under climate change were analyzed for two meteorological stations on the Island of Montreal: McGill (1872–1986) and Pierre-Elliott-Trudeau (P-E-T, formerly Dorval) Airport (1942–2014). A linear trendline analysis, the Mann–Kendall (MK) test and the two-sample Kolmogorov–Smirnov (KS) test were conducted to assess specific climate trends. On a 100-year basis, temperature increased 1.88°C (34%) and 1.18°C (19%) at the McGill and P-E-T Airport sites, respectively, while annual rainfall increased 23.9 mm y−1 (2.3%) and 138.8 mm y−1 (15%) over the same period. The frequency of 50% (every other year) and 95% (every year) annual maximum daily rainfall events showed decreasing trends for the McGill station, but increasing trends for the P-E-T Airport station. Growing degree-days and growing season length are prone to being influenced by climate change and are critical to managing agricultural activities in the Montreal region; both showed increasing trends. At the same time, the onset of the growing season occurred earlier as time progressed.

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Spatio-temporal Variability and Trends of Mean and Extreme Rainfall Events in the Sudano-sahelian Region of Cameroon

10.21203/rs.3.rs-848441/v1 ◽

2021 ◽

Author(s):

Ibrahim NJOUENWET ◽

Lucie A. Djiotang Tchotchou ◽

Brian Odhiambo Ayugi ◽

Guy Merlin Guenang ◽

Derbetini A. Vondou ◽

...

Keyword(s):

Climate Change ◽

Extreme Rainfall ◽

Temporal Variations ◽

Annual Rainfall ◽

Drought Risk ◽

Extreme Rainfall Events ◽

Rainfall Events ◽

Precipitation Concentration ◽

Spatio Temporal ◽

The Impact

Abstract The Sudano-Sahelian region of Cameroon is mainly drained by the Benue, Chari and Logone rivers, which are very useful for water resources, especially for irrigation, hydropower generation, and navigation. Long-term changes in mean and extreme rainfall events in the region may be of crucial importance in understanding the impact of climate change. Daily and monthly rainfall data from twenty-five synoptic stations in the study area from 1980 to 2019 and extreme indices from the Expert Team on Climate Change Detection and Indices (ETCCDI) measurements were estimated using the non-parametric Modified Mann-Kendall test and the Sen slope estimator. The precipitation concentration index (PCI), the precipitation concentration degree (PCD), and the precipitation concentration period (PCP) were used to explore the spatio-temporal variations in the characteristics of rainfall concentrations. An increase in extreme rainfall events was observed, leading to an upward trend in mean annual. Trends in consecutive dry days (CDD) are significantly increasing in most parts of the study area. This could mean that the prevalence of drought risk is higher in the study area. Overall, the increase in annual rainfall could benefit the hydro-power sector, agricultural irrigation, the availability of potable water sources, and food security.

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Detection of trends for extreme events of precipitation in the Metropolitan Region of Belo Horizonte through statistical methods

RBRH ◽

10.1590/2318-0331.0318170134 ◽

2018 ◽

Vol 23 (0) ◽

Cited By ~ 1

Author(s):

Aline de Araújo Nunes ◽

Eber José de Andrade Pinto ◽

Márcio Benedito Baptista

Keyword(s):

Climate Change ◽

Extreme Rainfall ◽

Threshold Value ◽

Metropolitan Region ◽

Extreme Weather Events ◽

Annual Number ◽

Extreme Precipitation Events ◽

Belo Horizonte ◽

The City ◽

Precipitation Events

ABSTRACT Extreme weather events have emerged as one of the main manifestations of climate change, being that the mitigation of the elapsed impacts demand studies of the magnitude and frequency of their occurrence. This study aims to identify the trends of extreme precipitation events in the Metropolitan Region of Belo Horizonte, especially concerning their frequency. The trends of precipitation were studied with especial regard to the indices set by ETCCDMI (Expert Team on Climate Change Detection Monitoring and Indices), including time series of annual number of rainy days above a certain threshold recorded at fourteen rainfall gauging stations. One stage of this study consisted in surveying the flood occurrence in the area, besides analyzing the precipitation data corresponding to date of flood occurrences, in order to establish a threshold value beyond which an event would entail potential impacts. No regional index pattern could be set based on such results, although the rainfall station located in the city of Belo Horizonte reported a statistically significant increase in daily precipitation events above 10, 20, 30 and 40 mm, in maximum precipitation recorded over five consecutive days, in daily intensity, and in total annual precipitation. Abrupt changes in rainfall series were also recorded. The results have indicated that the city may be potentially impacted by extreme rainfall increase, probably associated to changes in temperatures on regional and local scales.

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Analysis of the combined and single effects of LULC and climate change on the streamflow of the Upper Blue Nile River Basin (UBNRB): Using statistical trend tests, remote sensing landcover maps and the SWAT model

10.5194/hess-2017-685 ◽

2017 ◽

Cited By ~ 2

Author(s):

Dagnenet F. Mekonnen ◽

Zheng Duan ◽

Tom Rientjes ◽

Markus Disse

Keyword(s):

Climate Change ◽

Change Detection ◽

Swat Model ◽

Extreme Rainfall ◽

Base Flow ◽

Annual Rainfall ◽

Cultivated Land ◽

Lulc Change ◽

Extreme Rainfall Events ◽

Run Off

Abstract. Understanding the response of land use/land cover (LULC) and climate change has become a priority issue for water management and water resource utilization of the Nile basin. This study assesses the long-term trends of rainfall and streamflow to analyse the response of LULC and climate changes on the hydrology of the UBNRB. The Mann–Kendal (MK) trend tests showed no statistically significant changes in daily, monthly and annual rainfall. Tests for mean annual and seasonal streamflow showed a statistically significant and increasing trend. Landsat satellite images for 1973, 1985, 1995 and 2010 were used for LULC change detection. The LULC change detection findings indicate the conversion of forest land to cultivated land during the period 1973–2010. Natural forest decreased from 17.4 % to 14.4 %, 12.2 % and 15.6 % while cultivated land increased from 62.9 % to 65.6 %, 67.5 % and 63.9 % from 1973 to 1985, 1995 and 2010 respectively. The hydrological SWAT model result showed that mean annual streamflow increased by 15.6 % between the 1970s and the 2000s due to the combined effect of LULC and climate change. The single effect of LULC change on streamflow analysis suggested that LULC change significantly affects surface run-off and base flow. This could be attributed to the 5.1 % reduction in forest coverage and 4.6 % increase in cultivated land. Effects of climate change revealed that increased rainfall intensity and number of extreme rainfall events from 1971 to 2010 have greatly affected the surface run-off and base flow of UBNRB.

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ANALYSIS OF TRENDS OF EXTREME RAINFALL EVENTS USING MANN KENDALL TEST: A CASE STUDY IN PAHANG AND KELANTAN RIVER BASINS

Jurnal Teknologi ◽

10.11113/jt.v78.9696 ◽

2016 ◽

Vol 78 (9-4) ◽

Cited By ~ 2

Author(s):

Mazlina Alang Othman ◽

Nor Azazi Zakaria ◽

Aminuddin Ab. Ghani ◽

Chun Kiat Chang ◽

Ngai Weng Chan

Keyword(s):

Climate Change ◽

River Basin ◽

Extreme Event ◽

Extreme Rainfall ◽

River Basins ◽

Peninsular Malaysia ◽

Extreme Rainfall Events ◽

Rainfall Events ◽

Mk Test ◽

Kelantan River Basin

Climate change leads to changes in rainfall and extreme event. This phenomenon has already begun to transform the rainfall patterns in Malaysia. It was clearly proven when the northern and eastern states of Peninsular Malaysia such as Kelantan, Terengganu, Pahang, Perak and Johor were hit by the catastrophic floods in December 2014, events that have been described as the worst in decades. Although there are a number of studies in climate change and extreme rainfall events in Malaysia, there are still large knowledge gaps about their relationship. Understanding the shifts and predicting changing trends in rainfall distribution is needed for predicting and managing the floods. In this paper, Mann Kendall (MK) test and Sen's Slope estimator are employed to determine the trend of extreme rainfall events of various storm durations in the Pahang and Kelantan river basins. The results indicate that annual maximum daily rainfall for Pahang River basin and Kelantan River basin increased throughout 45 years. Results show that the percentage of stations with statistically significant trend (at 0.05 significance level) in the Kelantan River basin are higher compared to the Pahang River basin. Percentage of stations showing increasing trends were much higher for short duration rainfall (10, 30 and 60 minutes and 3 hours) compared to long duration rainfall (6, 12, 24, 48, 120 and 240 hours). This study will be useful for planning, designing and managing floods and stormwater systems in this area

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Trends and Interannual Variability of Extreme Rainfall Indices over Cameroon

Sustainability ◽

10.3390/su13126803 ◽

2021 ◽

Vol 13 (12) ◽

pp. 6803

Author(s):

Derbetini A. Vondou ◽

Guy Merlin Guenang ◽

Tchotchou Lucie Angennes Djiotang ◽

Pierre Honore Kamsu-Tamo

Keyword(s):

Climate Change ◽

Time Series ◽

Extreme Rainfall ◽

Annual Rainfall ◽

Agricultural Activity ◽

Economic Activities ◽

Intensity Index ◽

Climatic Regions ◽

Expert Team ◽

Annual Total

Central African citizens are highly vulnerable to extreme hydroclimatic events due to excess precipitation or to dry spells. This study makes use of CHIRPS precipitation data gridded at 0.05° × 0.05° resolution and extended from 1981 to 2019 to analyze spatial variabilities and trends of six extreme precipitation indices defined by the Expert Team on Climate Change Detection and Indices (ETCCDI) over Cameroon. They are the number of wet days (RR1), the simple daily intensity index (SDII), the annual total precipitation from days greater than the 95th percentile (R95ptot), the maximum number of consecutive wet days (CWD), the maximum number of consecutive dry days (CDD), the number of very heavy rainfall (RR20). The standard precipitation index (SPI) time series were also examined in the five agro-climatic regions of the domain. The pattern of annual precipitation was first checked over the entire domain. We obtain a well-known pattern showing a decreased precipitation northward with the highest values around the Atlantic Ocean coast. The analysis shows that all indices represent patterns approximately similar to that of annual rainfall except CDD where the spatial south-north gradient is reversed. RR20 shows the lowest spatial variability. Trend study of RR1 indicates negative values south of the domain and predominated positive values in the northern part, where CDD, on the contrary, shows a decreased trend. The highest trends are observed in the northernmost area for CWD and around the coast for SDII and R95ptot. SPI time series indicate an alternative dry and wet period and the years between 1990 and 2000 witnessed more annual wet conditions. Such a study is very important in this domain where variabilities of climatic components are very high due to climate change impact and diversified relief. The results can serve as a reference for agricultural activity, hydropower management, civil engineering, planning of economic activities and can contribute to the understanding of the climate system in Cameroon.

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Rainfall variability and floods occurrence in the city of Bamenda (Northwest of Cameroon)

Present Environment and Sustainable Development ◽

10.1515/pesd-2017-0006 ◽

2017 ◽

Vol 11 (1) ◽

pp. 65-82 ◽

Cited By ~ 3

Author(s):

Saha Frederic ◽

Tchindjang Mesmin

Keyword(s):

Rainfall Variability ◽

Extreme Rainfall ◽

Annual Rainfall ◽

Annual Number ◽

Extreme Rainfall Event ◽

Average Profile ◽

Flood Flows ◽

Annual Distribution ◽

Subsistence Activities ◽

The City

Abstract This study is based on analysis of rainfall data from 1951-2010 collected at the climatic station of Bamenda. We also use the results of a questionnaire survey applied to 172 households in at-risk neighborhoods. The inventory of some cases of flooding that occurred in the city of Bamenda was done through focus groups. The appreciation of the socio-economic and demographic environment is based on surveys among Cameroonian Households by the National Institute of Statistics (NIS) and General Census of Population and Housing. Statistical examination revealed that annual rainfall in the city of Bamenda experienced a break in 1958. This break buckled the wettest decade of the series. After three decades of worsening, rainfall is experiencing rising since early 1990. The average profile of the annual distribution of rainfall shows a concentration of over 53% in 03 months (July, August and September). During these three months, the rivers of the city know their flood flows and populations in the valleys are affected. The analysis of the annual number of rainy days shows a downward trend and an increase of extreme rainfall event frequency (≥50mm in 24h). It is also apparent that more and more years are experiencing erratic distribution of their precipitation. Then, the perception of people is significantly reduced. Subsistence activities are also affected and development is facing new subtleties. In conclusion, the rainfall experienced strong variability in the city of Bamenda. This situation reinforces the risk of flooding by increasing flood water and increasing the vulnerability of populations.

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Rainfall Variability and Trends over the African Continent Using TAMSAT Data (1983–2020): Towards Climate Change Resilience and Adaptation

Remote Sensing ◽

10.3390/rs14010096 ◽

2021 ◽

Vol 14 (1) ◽

pp. 96

Author(s):

Niranga Alahacoon ◽

Mahesh Edirisinghe ◽

Matamyo Simwanda ◽

ENC Perera ◽

Vincent R. Nyirenda ◽

...

Keyword(s):

Climate Change ◽

River Basin ◽

Water Resource Management ◽

Rainfall Variability ◽

Decision Makers ◽

Annual Rainfall ◽

African Continent ◽

Climate Zones ◽

Mk Test ◽

Rainfall Trends

This study reveals rainfall variability and trends in the African continent using TAMSAT data from 1983 to 2020. In the study, a Mann–Kendall (MK) test and Sen’s slope estimator were used to analyze rainfall trends and their magnitude, respectively, under monthly, seasonal, and annual timeframes as an indication of climate change using different natural and geographical contexts (i.e., sub-regions, climate zones, major river basins, and countries). The study finds that the highest annual rainfall trends were recorded in Rwanda (11.97 mm/year), the Gulf of Guinea (river basin 8.71 mm/year), the tropical rainforest climate zone (8.21 mm/year), and the Central African region (6.84 mm/year), while Mozambique (−0.437 mm/year), the subtropical northern desert (0.80 mm/year), the west coast river basin of South Africa (−0.360 mm/year), and the Northern Africa region (1.07 mm/year) show the lowest annual rainfall trends. There is a statistically significant increase in the rainfall in the countries of Africa’s northern and central regions, while there is no statistically significant change in the countries of the southern and eastern regions. In terms of climate zones, in the tropical northern desert climates, tropical northern peninsulas, and tropical grasslands, there is a significant increase in rainfall over the entire timeframe of the month, season, and year. This implies that increased rainfall will have a positive effect on the food security of the countries in those climatic zones. Since a large percentage of Africa’s agriculture is based only on rainfall (i.e., rain-fed agriculture), increasing trends in rainfall can assist climate resilience and adaptation, while declining rainfall trends can badly affect it. This information can be crucial for decision-makers concerned with effective crop planning and water resource management. The rainfall variability and trend analysis of this study provide important information to decision-makers that need to effectively mitigate drought and flood risk.

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