Trend In Annual Rainfall Research Articles

Aosta Valley Mountain Springs: A Preliminary Analysis for Understanding Variations in Water Resource Availability under Climate Change

The availability of freshwater resources in mountain areas has been affected by climate change impacts on groundwater storage mechanisms. As a web of complex interactions characterizes climate systems, understanding how water storage conditions have changed in response to climate-driven factors in different Italian contexts is becoming increasingly crucial. In order to comprehend the relationship between changes in weather conditions and water availability in the Aosta Valley region and how their trends have changed over the last decade, a 7-year discharge series of different Aosta Valley springs (Promise, Alpe Perrot, Promiod, Cheserod) and precipitation data are analysed. Precipitation and flow rate trends using the Mann–Kendall and Sen’s slope trend detection tests were also performed. Not all of the Aosta Valley mountain springs detected seem to respond to the climate variation with a decrease in their stored water resources. Unlike Promiod, Alpe Perrot, Cheserod, and Promise springs have experienced an increase in water discharged amount during the detected 7-year period. This behavior occurs despite the available precipitation data for the associated Sant Vincent, Aymaville-Viayes, La Thuile-Villaret, Champdepraz meteorological stations revealing an overall decreasing trend in annual rainfall (mm), with a slight increase in intensity (mm/day) as a result of the reduction in rainfall events (number of rainy days).

The evolving roles of intensity and wet season timing in rainfall regimes surrounding the Red Sea

The Red Sea is surrounded by a diverse mixture of climates and is spanned by opposite hydrologic end-uses and geopolitical states. Unique water supply management challenges on both sides (related to agricultural and trans-boundary conflict in East Africa, and to groundwater depletion in the Arabian Peninsula) are made more severe by a rising demand, which underscores the importance of understanding shifts in rainfall supply to aid effective action. In this study, we characterize the relative importance of rainfall intensities to annual rainfall, the onset and duration of wet seasons, and the (statistically significant) trends in each of these over the region from 1981 through 2020 using daily gridded (0.05°) precipitation estimates. Results show that heavy rainfall (above 20 mm d−1) does not necessarily benefit annual totals, as the wettest regions are shaped by moderate (between 5 and 20 mm d−1) rainfall coupled with prolonged wet seasons. Observed trends in annual rainfall are underlain by interactions between shifting wet season lengths and rainfall intensities. Wet season length increases for 26% of the region, dampening the inherent drying resulting from shifts toward less-intense rainfall, and bolstering the inherent wetting from shifts toward more-intense rainfall. Regions shifting toward less- (more-)intense rainfall without an expanding wet season generally show negative (insignificant) rainfall trends. This reveals an important control that wet-day frequency has over wet-day intensity alone in shaping annual rainfall changes. We emphasize that the large-scale distribution of these shifts and their regional importance should punctuate cooperative efforts in sustainable resource management and transboundary governance.

A Trend Analysis of Climatic Variables in the Karimganj District of Assam, India

Objectives: The main goal of this research is to analyse the trends of climatic variables in the Karimganj district of Assam. The study examines the trend of seasonal and annual temperature maximum, temperature minimum, rainfall and relative humidity for the period 1981-2020. Methods: A non-parametric Mann-Kendall (MK) technique has been employed to establish statistically significant trend in the series. The magnitude of a time series trend has been evaluated by Sen’s slope test. Trend lines and time series graphs are used for better understanding of trends. Findings: It has been found that annual and seasonal temperature maximum (Tmax) have a significant negative trend over the period except post monsoon season. There is no significant trend in the annual temperature minimum (Tmin) series but seasonal mean temperature minimum is showing a significant positive trend at different levels of significance during all four seasons. Except winter season, annual rainfall series and all other seasonal average rainfall series are showing significant positive trends. The seasonal averages and annual relative humidity are showing statistically significant positive trends over the period. Novelty: The study is unique and innovative for Karimganj district of Assam to best of our knowledge. From the analysis, the study claims that climate change is occurring in the district. To combat the impact of climate change, participation of people in adaptations practices and government intervention in the form of mitigation policies are necessary. JEL Classification: Q50, Q54 Keywords: Karimgani; climate change; rainfall; temperature; relative humidity; Assam

Spatio‐temporal rainfall variability and trend analysis in the Tekeze‐Atbara river basin, northwestern Ethiopia

AbstractSpatial and temporal rainfall variability analysis at a basin scale is essential to understand water availability for sustainable water resource management. This study investigated the spatial distribution and temporal rainfall trend in the Tekeze river basin using daily rainfall data collected from 43 meteorological stations with records from 1960 to 2019. Coefficient of variation, seasonality index (SI) and trend index were used to evaluate monthly, seasonal and annual rainfall variability in the basin. The non‐parametric Mann‐Kendall's test was used to understand any rainfall trends. Results showed that there is moderate annual rainfall variability in the basin. Rainfall variability is higher in the Tsedey, Bega and Belg than kiremt season. SI results showed that majority of the Tekeze river basin is categorized as seasonal, most of the rain occurring in less than 3 months. Overall, Mann‐Kendall's test result revealed that there is no significant annual rainfall trend in the basin except for four stations. The seasonal rainfall characteristics and short duration of rain in the basin indicate that there is a need to implement water harvesting measures during the wet season for use in the dry periods.

Links between precipitation, circulation weather types and orography in central Italy

AbstractRecent analyses of satellite and surface observations reported a negative annual rainfall trend in central Italy. The complex orography of the Apennines and the strong influence of climate change in the Mediterranean basin complicates the explanation of such trends and their spatial variability. This work aims at describing the link between circulation weather types, orography and precipitation patterns observed in central Italy, as a first step towards the understanding of such climate trends. Using ERA5 reanalysis data from 1951 to 2019, four weather types are identified as most responsible for the spatial variability of rainfall in central Italy. They are associated with cyclonic circulations characterized by high water vapour transport coming from west, south‐west, south‐east and north‐east. The analysis of wind speed and precipitation climatology for the period 1951–2019, as derived from both surface observations and reanalysis, confirms a strong influence of moist south‐westerly fluxes over all the domain, while the effect of north‐easterly fluxes remains confined to the Apennines and the Adriatic coast. ERA5 overestimates annual rainfall in most parts of the region, except on the north‐central Apennines where the underestimation reaches average values of 300 mm. The analysis of circulation weather types and their associated precipitation variability demonstrates that this deficit can be ascribed to a wrong representation of the orographic precipitation component as seen by ERA5 in correspondence of cyclonic north‐easterly and westerly flows impinging towards the north‐central Apennines. Indeed the precipitation associated with north‐easterly and westerly fluxes shows the strongest modulation by orography. This interaction and its possible modification by climate change effects should be considered in future studies investigating recent climate trends in central Italy.

Statistical and temporal trends analysis of rainfall in Bundelkhand region, Central India

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.

Woody plant decline in the Sahel of western Niger (1996–2017):is it driven by climate or land use changes?

Although a recovery of woody vegetation has been observed throughout the Sahel, western Niger has not followed the overall satellite-derived greening trend. While satellite imagery can be used to study overall patterns and trends, only field observations can provide insights in the dynamics of woody plant populations. Here we used field data from 29 sites in the Dantiandou district in Niger to study woody species composition, plant density, crown cover, basal area, foliage and wood mass from 1996 to 2017. All sites show a decrease in woody plant parameters with a faster decrease in rangeland than in agricultural land. Most of the decrease is due to the loss of shrubs, while trees do not change significantly. When field observations were scaled up to the district level using land use maps, shrub density decreased from 342 to 155 ha−1 in agricultural land, and from 1567 to 250 ha−1 in rangeland. Trends in annual rainfall and soil moisture during the study period were not significant and cannot explain the decrease of woody vegetation. Instead, the expansion of cropped areas, shortened crop-fallow cycles and increasing pressure on wood resources to satisfy demand for fuel and construction materials may have contributed to the decline.

EVALUATION OF RAINFALL TRENDS DUE TO CLIMATE CHANGE: A CASE STUDY OF SAMARU, ZARIA

Rainfall is the major source of water for agricultural activities in Nigeria, but there has been a major variation due to climate change. This study is to assess the change in rainfall trend due the impact of climate change in Samaru, Zaria Kaduna State. Rainfall data from 1981 – 2018 (38 years) were collected from the Nigerian Meteorological Agency (NIMET). The data was analyzed using Excel and XL-Statistics to evaluate the mean, standard deviation and coefficient of variation of monthly and annual rainfall and other statistical parameter. The study revealed that there is a significant change in the trend of annual rainfall as the highest rainfall was recorded in year 1994 with a value of 1487 mm and lowest rainfall in 1999 as 440 mm. The highest average monthly rainfall data is between July to September and a peak rainfall in August with an average value of 547 mm. This analysis provide useful information to farmers which can be used a basis for planning annual crop planting and also water resources planning such as in irrigation scheduling.

Observed Changes in Meteorological Drought Events during 1981–2020 over Rwanda, East Africa

Drought is one of the most complex natural phenomena affecting the life and livelihood of people, especially in the current time of human-induced climate change. This research employs ground-based observations to assess the recent spatiotemporal characteristics of meteorological drought events over Rwanda. The drought is examined based on the Standardized Precipitation Evapotranspiration Index (SPEI) and Standardized Precipitation Index (SPI) at seasonal and annual time scales from 1981 to 2020. The Man–Kendal test was used to evaluate the trends in rainfall, temperature, and SPEI values at the annual scale and during the March to May (MAM) and October to December (OND) seasons. The analysis revealed nonsignificant trends in annual (8.4 mm/decade), MAM (−3.4 mm/decade), and OND (4.5 mm/decade) rainfall, while an apparent significant increasing trend in surface air temperature was obtained during the MAM (0.19 °C/decade), OND (0.2 °C/decade), and annual (0.23 °C/decade) time slices. Overall, the SPEI characteristics indicated that the country is more prone to moderate drought events than severe and extreme drought events during MAM and OND seasons. However, the intensity, duration, and frequency differ spatially among seasons. The findings of this study inform policy and decision-makers on the past experienced drought behavior, which can serve as a baseline for future drought mitigation and adaptation plans.

Analysis of rainfall trends over Tripura

Rainfall in India has very high temporal and spatial variability. The rainfall variability affects the livelihood and food habits of people from different regions. In this study, the rainfall trends in two stations in the north-eastern state of Tripura, namely Agartala and Kailashahar have been studied for the period 1955-2017. The state experiences an annual mean of more than 2000 mm of rainfall, out of which, about 60% occurs during the monsoon season and about 30% in pre-monsoon. An attempt has been made to analyze the trends in seasonal and annual rainfall, rainy days and heavy rainfall in the two stations, during the same period.Non-parametric Mann-Kendall test has been used to find out the significance of these trends. Both increasing and decreasing trends are observed over the two stations. Increasing trends in rainfall, rainy days and heavy rainfall are found at Agartala during pre-monsoon season and decreasing trends in all other seasons and at annual scale. At Kailashahar, rainfall amount (rainy days & heavy rainfall) is found to be increasing during pre-monsoon and monsoon seasons (pre-monsoon season). At annual scale also, rainfall and rainy days show increasing trends at Kailashahar. The parameters are showing decreasing trends during all other seasons at the station. Rainy days over Agartala show a significantly decreasing trend in monsoon, whereas no other trend is found to be significant over both the stations.

Potential Impact of Climate Variability on Tea Farming on the Mambilla Plateau, Taraba State, Nigeria

This study examined the potential impact of climate variability on tea farming on the Mambilla Plateau, Taraba State, Nigeria. Data for this study was generated through primary and secondary sources. The primary data were generated from field observation. Secondary desk review of existing literature and online resources were used. Archival data on climatic elements were obtained from the Upper Benue River Basin Development Authority (UBRBDA) Meteorological stations at Gembu and Maisamari, both on the Mambilla plateau. The data was analyzed using inferential statistics such as simple correlation coefficient (r), regression and time series analysis. The result of the findings on the trends of annual rainfall in the study area shows that rainfall amount, length of rainy season (LRS) and relative humidity were decreasing, with late onset and cessation of rains in the area. The trend of maximum and minimum temperature as well as wind speed was increasing owing to increasing rate of deforestation in the area. Climate variability and change has both advantages and disadvantages to the growth and development of tea which ultimately affect its production. Variability in precipitation and temperature has considerable impacts on tea quality and yields by altering the quantities and types of pests and weeds in and around tea farms. The findings of the study reveal that the global surface temperature has changed and will continue to change in the nearest future. Hence, the need to devise suitable means of adaptation and mitigation to the challenges of climate change in the area. Based on the findings, the study recommends the use of improved tea crop variety, involvement of local communities in climate change adaptation strategies, increase dissemination of climate information and education of the farmers on most suitable local adaptation strategies.

Dryland Pastoralism Climate Landscape and Food Security in the Suam River Basin of Kenya

River basins in the drylands of Sub-Saharan Africa have traditionally been utilized for pastoral livelihoods under communal land tenure. Communities in West Pokot in Kenya have continued to experience increased precipitation and temperature as a result of climate variability and change. This study aimed at assessing the impact of climate variability and change at micro-basin level in order to address research and policy gaps on climate change and food security as policy arena shifts from centralized to decentralized governance in Kenya. Primary quantitative data was collected from 387 households’ perceptions of climate variability and change and its implications on food security were measured. Food security index score was calculated. The annual rainfall trend over Suam river basin for the period (1981-2020), was characterized by a linearly increasing annual rainfall trend. Mann Kendall test Z-statistics and Tau were at 2.3578 and 0.0720 respectively. The basin experienced the highest rainfall variability during the first decade (1981-1990) with the highest coefficient of rainfall variation noted at 11.5%. The highest temperature was recorded in the third decade (2001-2010) and fourth decade (2011-2020) at 27.0 and 28.2 degrees Celsius respectively. However, the overall index score for food security was 55.78 with food availability scoring the highest index, mean (SD) of 63.41 (36.52). This was attributed to households’ practice of both nomadic pastoralism and agro-pastoralism activities. Climate variability and change, have resulted in increased amount of rainfall received providing for opportunity investment in rain water harvesting to support both pastoralism and agro-pastoralism production to enhance food security.

Trend Analysis of Annual Rainfall and Rainy Days Over Pune District of Maharashtra

Rainfall analysis would enhance the management and effective utilization of water resources. Analysis of trend is useful to examine the long term trends in rainfall and rainy days over. The present study has been undertaken in fourteen Tehsils of the Pune district to study rainfall and rainy days trend using Mann-Kendall Test and Sen’s Slope method and GIS based maps are prepared. The annual rainfall trend over the most of tehsils has been increased with increasing rainy days while, rainfall trend in Ambegaon, Baramati tehsils decreased with increasing rainy days and in Junnar and Purandar tehsils it was decreased with decreasing rainy days. Spatial variation in trends of annual rainfall showed in a map prepared in the GIS environment.

Rainfall and Rainy Days Trend Analysis in Miraj Tahsil of Sangli District

The study has been carried out to investigate and asses the significance of the potential trend on annual, seasonal and monthly basis using the data period between 1982 to 2018 for rainfall and rainy days. MannKendall test and Sen's slope estimate test were applied to identify the existing trend direction and Sen's slope estimator test were used to detect the trend direction and magnitude of change over time. The test results showed increasing annual rainfall and rainy days trend over the tahsil. The seasonal rainfall and rainy days showed decreasing trend for summer season and decreasing trend for northeast monsoon and southwest monsoon seasons. The monthly rainfall and rainy days trend showed increasing trend for July to November months and decreasing days for May month. The weekly rainfall and rainy days trend showed decreasing trend for MW21-MW24, MW30, MW33 and MW43-MW45.

Rainfall analysis over Kalyana Karnataka districts for resource planning in agriculture

The study has been made to analyze the rainfall of six districts of Kalyana Karnataka by utilizing the past 50 years (1971-2020) rainfall data. The rainfall data was critically examined and analyzed statistically for annual and seasonal values followed by computation of trend analysis of annual rainfall. The results revealed that, the highest mean annual rainfall was recorded at Bidar (917.8 mm) followed by Yadgir (877.8 mm) and the lowest at Ballari (559.8 mm). The CV varied between 24.0% (Bidar) to 32.6% (Yadgir). From the skewness analysis it was observed that, skewness varied from 0.3 (Bidar and Koppal) to 0.7 (Yadgir and Raichur). The Yadgir district showed zero Kurtosis and the remaining districts were found to be negatively Kurtosis and it varied from -0.1 to -0.6. The Raichur district showed 0.6 positively Kurtosis. From regression analysis, it was found that, the slopes of regression line of annual rainfall are positive at Bidar, Raichur and Koppal. This shows that these districts have increasing annual rainfall trend. However, since the correlation coefficient value (R2) is too low, the increasing trend is not significant. The remaining stations (Kalaburgi, Yadgir and Ballari) showed negative slope of regression line. This indicates these stations have decreasing trend of annual rainfall. The mean monsoon season rainfall varied between 315.3 mm (Ballari) to 705.8 mm (Bidar) and the CV was found to be more than 30% in all the districts which indicate highly erratic rainfall and the rainfall is not much dependable around the mean rainfall. The skewness analysis revealed that, all the stations showed positive skewness and it varied between 0.3 (Raichur and Koppal) to 0.9 (Yadgir).

Identification of changes in rainfall pattern in paddy growing areas in Sri Lanka: A case study in Anuradhapura district

It is now widely accepted that the global climate is changing with increasing greenhouse gas concentration in the atmosphere due to human activities. There is enough evidence for more negative impacts of climate change on world agricultural sector. As an agricultural country, Sri Lanka is also experiencing some inevitable consequences due to changing rainfall onset, distribution and the amount. Standardized Precipitation Index (SPI) is a drought monitoring index which is developed for identifying rainfall anomalies with respect to the past data in the same location for specific time scales. The aim of this study was to identify the changes in rainfall patterns using SPI in Anuradhapura district which is one of the major paddy growing areas in Sri Lanka. Monthly rainfall data were collected from four Meteorological Stations viz, Anuradhapura, Maha Iluppallama, Maradankadawala and Kebithigollewa for the period of 1980-2018. Five months SPI values were computed to represent Yala & Maha cultivation seasons and 12 months SPI values were computed to represent the annual rainfall anomalies. Mann Kendal Test was used to identify the trends in selected SPI time series. The results of the study revealed that, there are significant increasing trends in total annual rainfall in Anuradhapura district indicating low risk of having drought years in future. The significant increasing trend in SPI values in Yala & Maha seasons in both Anuradhapura and Maha Iluppallama stations imply that there is a high chance of receiving enough water for cultivation in both seasons in near future. Further, a significant decrease could be observed in total annual and Yala season’s SPI values in Maradankadawala indicating a high potential of having droughts. However, Kebithigollewa does not show any significant change in total annual, Yala or Maha seasons rainfall patterns. Finally, it can be concluded that, as Anuradhapura, Maha Iluppallama and Kebithigollewa areas are getting slightly wetter, the paddy cultivation in the Western and Southwestern areas of Anuradhapura district would not be severely affected due to changing rainfall patterns. However, as Maradankadawala area is getting slightly dryer with the changing rainfall patterns, strengthening water conservation techniques would be better for paddy cultivation in the Southeastern area of Anuradhapura district in order to adapt to the incoming dry periods.

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

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.

Spatiotemporal Trend Analysis of Temperature and Rainfall over Ziway Lake Basin, Ethiopia

Rainfall and temperature trends detection is vital for water resources management and decision support systems in agro-hydrology. This study assessed the historical (1983–2005) and future (2026–2100) rainfall, maximum temperature (Tmax), and minimum temperature (Tmin) trends of the Ziway Lake Basin (Ethiopia). The daily observed rainfall and temperature data at eleven stations were obtained from the National Meteorological Agency (NMA) of Ethiopia, while simulated historical and future climate data were obtained from the Coupled Model Intercomparison Project 5 (CMIP5) datasets under Representative Concentration Pathways (RCP) of 4.5 and 8.5. The CMIP5 datasets were statistically downscaled by using the climate model data for hydrologic modeling (CMhyd) tool and bias corrected using the distribution mapping method available in the CMhyd tool. The performance of simulated rainfall, Tmax, and Tmin of the CMIP5 models were statistically evaluated using observation datasets at eleven stations. The results showed that the selected CMIP5 models can reasonably simulate the monthly rainfall, Tmax, and Tmin at the majority of the stations. Modified Mann–Kendall trend test were applied to estimate the trends of annual rainfall, Tmax, and Tmin in the historical and future periods. We found that rainfall experienced no clear trends, while Tmax, and Tmin showed consistently significant increasing trends under both RCP 4.5 and 8.5 scenarios. However, the warming is expected to be greater under RCP 8.5 than RCP 4.5 by the end of the 21st century, resulting in an increasing trend of Tmax and Tmin at all stations. The greatest warming occurred in the central part of the basin, with statistically significant increases largely seen by the end of the 21st century, which is expected to exacerbate the evapotranspiration demand of the area that could negatively affect the freshwater availability within the basin. This study increases our understanding of historic trends and projected future change effects on rainfall- and evapotranspiration-related climate variables, which can be used to inform adaptive water resource management strategies.

Analysis of Spatio-temporal rainfall trends and rainfall variability in Botswana between 1958 and 2019

Environments with a climatic characteristic of semi-aridity exhibit high rainfall variability, increasing significantly as the climate changes. In this study, rainfall concentration and Spatio-temporal trends in annual and seasonal (November to March) rainfall in Botswana were analyzed. The satellite data (1958-2019) is obtained from the Southern African Science Service Centre for Climate Change and Adaptive Land Management and the Climate Toolbox. The Mann–Kendall trend test (MK), autocorrelation function (ACF), relative percentage change (RPC), precipitation concentration index (PCI), and Theil–Sen's slope estimator (β) methods were adopted for data analysis. The regions include Gaborone, Maun, Francistown, Serowe, Kasane, Tsabong, Ghanzi, and Pandamatenga. The results indicated that the magnitude of change of change of the significant downward trends in the annual rainfall was found to be -1.11 mm/year at Maun, -1.62 mm/year at Ghanzi, -0.33 mm/year at Pandamatenga, and -0.25 mm/year at Tsabong. The magnitude of change of change of the significant downward trends in the seasonal rainfall was between -0.60 mm/year at Pandamatenga and -0.19 mm/year at Tsabong. All these regions, except Ghanzi, experienced a downward trend in the rainfall distribution. This is owing to the synoptic characteristic of the below-average geopotential heights over Ghanzi. Which might exacerbate the formation of convective systems, leading to a positive rainfall trend at Ghanzi. The annual calculated PCI values are divided into three classes; PCI>10≤15, PCI>16≤20, and PCI>20. The Mann-Kendall analysis of the PCI values indicates that all the regions experienced a downward rainfall trend, implying that it is heading toward a uniform to a moderate distribution. There were distinct patterns that emerged from the Pandamatenga region, indicating a strongly irregular distribution. The regions of Kasane, Maun and Francistown, demonstrated moderate to an irregular distribution. For Gaborone and Francistown, results showed occurrences of a moderate to strongly irregular distribution.

Trend of annual maximum rainfall in Campania region (Southern Italy)

AbstractExtreme rainfall events are increasing in both number and intensity at global scale; however, it is hard to quantify the impact of climate change at local scale given the strong temporal and spatial heterogeneity of this process. Moreover, limited data availability and its spatial variability requires significant effort to identify specific trends at the regional level. In this study, we attempt to construct a detailed description of rainfall patterns and trends over the Campania region, southern Italy. For this reason, the dataset of rainfall annual maxima in pre‐assigned durations was constructed using all available records and extended using interpolation methods such as inverse distance weighting and ordinary kriging methods. The rainfall dataset allowed actual trends over the region to be quantified using the Mann‐Kendall trend test and the record‐breaking analysis. The trend test reveals that most of the rainfall stations display no statistically significant trend, however, an increasing trend of extreme rainfall for short durations, in specific portions of the region, is observed.