scholarly journals Analysis of spatial variability and temporal trends of rainfall in Amhara region, Ethiopia

2019 ◽  
Vol 11 (4) ◽  
pp. 1505-1520 ◽  
Author(s):  
Melkamu Meseret Alemu ◽  
Getnet Taye Bawoke
Keyword(s):  
Trend Analysis ◽  
Water Resource Management ◽  
Rainfall Variability ◽  
Temporal Trends ◽  
Amhara Region ◽  
Rainfall Distribution ◽  
Rainfall Events ◽  
Precipitation Concentration Index ◽  
Droughts And Floods ◽  
Seasonality Index

Abstract Understanding rainfall distribution in space and time is crucial for sustainable water resource management and agricultural productivity. This study investigated the spatial distribution and temporal trends of rainfall in Amhara region using time series rainfall data of Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) for the period 1981–2017. Coefficient of variation, standardized anomaly index (SAI), precipitation concentration index (PCI) and seasonality index (SI) were used to evaluate rainfall variability and seasonality. Mann–Kendall's test was also employed for rainfall trend analysis. Results showed that the region has been experiencing variable rainfall events that cause droughts and floods over different years. SAI also witnessed the presence of inter-annual variability of rainfall with negative and positive anomalies in 59.46% and 40.54% of the analyzed years, respectively. PCI and SI results implied that the area had irregular and strong irregular rainfall distribution. Trend analysis results showed an overall increase in the annual and seasonal rainfall (except winter) during the study period. The information obtained from this study could serve as a proxy for rainfall variability and trend in the study area which might be used as input for decision-makers to take appropriate adaptive measures in various agricultural and water resources sectors.

scholarly journals Characterizing past and future trend and frequency of extreme rainfall in urban catchments: a case study

2020 ◽  
Vol 3 (1) ◽  
pp. 288-305
Author(s):  
Philip Mzava ◽  
Patrick Valimba ◽  
Joel Nobert
Keyword(s):  
Trend Analysis ◽  
Rainfall Variability ◽  
Extreme Rainfall ◽  
Dar Es Salaam ◽  
Extreme Rainfall Events ◽  
Maximum Rainfall ◽  
Rainfall Events ◽  
The Past ◽  
The Future ◽  
Urban Catchments

Abstract Urban communities in developing countries are one of the most vulnerable areas to extreme rainfall events. The availability of local information on extreme rainfall is therefore critical for proper planning and management of urban flooding impacts. This study examined the past and future characteristics of extreme rainfall in the urban catchments of Dar es Salaam, Tanzania. Investigation of trends and frequency of annual, seasonal and extreme rainfall was conducted, with the period 1967–2017 taken as the past scenario and 2018–2050 as the future scenario; using data from four key ground-based weather stations and RCM data respectively. Mann–Kendall trend analysis and Sen's slope estimator were used in studying changes in rainfall variability. Frequencies of extreme rainfall events were modeled using the Generalized Pareto model. Overall, the results of trend analysis provided evidence of a significant increase in annual and seasonal maximum rainfall and intensification of extreme rainfall in the future under the RCP4.5 CO2 concentration scenario. It was determined that extreme rainfall will become more frequent in the future, and their intensities were observed to increase approximately between 20 and 25% relative to the past. The findings of this study may help to develop adaptation strategies for urban flood control in Dar es Salaam.

scholarly journals Impact of Rainfall Variability on Crop Production within the Worobong Ecological Area of Fanteakwa District, Ghana

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Conrad Kyei-Mensah ◽  
Rosina Kyerematen ◽  
Samuel Adu-Acheampong
Keyword(s):  
Crop Production ◽  
Rainfall Variability ◽  
Potential Effect ◽  
Rainfall Data ◽  
Rainfall Pattern ◽  
Rainfall Distribution ◽  
District Office ◽  
Precipitation Concentration Index ◽  
The Face ◽  
Established Relationship

Crop production in the Fanteakwa District is predominantly rainfed, exposing this major livelihood activity to the variability or change in rainfall pattern. The net potential effect of severe changes in rainfall pattern is the disruption in crop production leading to food insecurity, joblessness, and poverty. As a major concern to food production in Ghana, this study seeks to show the relationship between the production of major crops and rainfall distribution pattern in the Worobong Agroecological Area (WAA) relative to food security in the face of climate change. The study analysed the variability in local rainfall data, examining the interseasonal (main and minor) rainfall distribution using the precipitation concentration index (PCI), and determined the pattern, availability of water, and the strength of correlation with crop production in the WAA. Data from the Ghana Meteorological Agency (GMet) spanning a 30-year period and grouped into 3 decades of 10 years each was used. Selected crop data for 1993-2014 was also obtained from the Ministry of Food and Agriculture’s District office and analyzed for trends in crop yield over the period and established relationship between the crop data and the rainfall data. Part of the result revealed that rainfall variability within the major seasons in the 3 groups was lower than the minor seasons. It further showed that yields of three crops have declined over the period. Among the strategies to sustain crop production is to make the findings serve as useful reference to inform discussions and policy on adaptive agricultural production methodologies for the area in the face of changing climate.

scholarly journals Climate Change Impact on Rainfall: How will Threaten Wheat Yield?

2018 ◽  
Vol 37 ◽  
pp. 03001
Author(s):  
K. Tafoughalti ◽  
E.M. El Faleh ◽  
Y. Moujahid ◽  
F. Ouargaga
Keyword(s):  
Climate Change ◽  
Rainfall Variability ◽  
Wheat Yield ◽  
Annual Rainfall ◽  
Strongly Correlated ◽  
Rainfall Distribution ◽  
Precipitation Concentration Index ◽  
Agrarian Economy ◽  
Cumulative Rainfall ◽  
Change Impact

Climate change has a significant impact on the environmental condition of the agricultural region. Meknes has an agrarian economy and wheat production is of paramount importance. As most arable area are under rainfed system, Meknes is one of the sensitive regions to rainfall variability and consequently to climate change. Therefore, the use of changes in rainfall is vital for detecting the influence of climate system on agricultural productivity. This article identifies rainfall temporal variability and its impact on wheat yields. We used monthly rainfall records for three decades and wheat yields records of fifteen years. Rainfall variability is assessed utilizing the precipitation concentration index and the variation coefficient. The association between wheat yields and cumulative rainfall amounts of different scales was calculated based on a regression model. The analysis shown moderate seasonal and irregular annual rainfall distribution. Yields fluctuated from 210 to 4500 Kg/ha with 52% of coefficient of variation. The correlation results shows that wheat yields are strongly correlated with rainfall of the period January to March. This investigation concluded that climate change is altering wheat yield and it is crucial to adept the necessary adaptation to challenge the risk.

scholarly journals Analysis of Historical Monthly, Seasonal and Annual Rainfall Variability (1990–2014) in Machakos Sub County, Kenya

2018 ◽  
Vol 6 (01) ◽  
Author(s):  
Christopher M. Indiatsy
Keyword(s):  
Rainwater Harvesting ◽  
Rainfall Variability ◽  
Climatic Conditions ◽  
Annual Rainfall ◽  
Correlation Technique ◽  
Precipitation Concentration Index ◽  
Considerable Uncertainty ◽  
Marginal Areas ◽  
Droughts And Floods ◽  
Central Kenya

Varying climatic conditions with increased uncertainty mainly in rainfall and temperature are salient features in marginal areas globally, adversely affecting farming activities particularly in Africa. Kenya experiences variations of annual rainfall with considerable uncertainty. These variations ranging from below 500mm to above 2000mm annually, cause droughts and floods respectively, affecting farming activities and yields. This study attempts to analyze historical monthly, seasonal and annual rainfall variability in Machakos sub County between 1990 – 2014. Studies on analysis of rainfall variability covered in Machakos have dwelt on broad and expansive areas of Eastern and South Eastern Kenya including Machakos, Kitui and Makueni Counties. Broad studies give generalized information which may not give true and adequate results for some specific areas. This has prompted the need to focus on a smaller area. This study focused on Machakos sub County, a semi arid area, East of Central Kenya highlands. Existing studies in the mentioned areas, mainly cover the period between 1930 - 1990. After this period, very scarce information exists. The main objective of the study was to establish the historical monthly, seasonal and annual rainfall variability in Machakos sub county between 1990 – 2014. Publications from Meteorological Department Nairobi and sub county Agricultural offices, provided rainfall data. Using SPSS, quantitative data was analyzed using descriptive statistics such as Means, Standard deviation and percentages. Inferential statistics using Pearson’s Correlation technique was used to determine relationships between variables. Coefficient of variability, Relative variability and Precipitation Concentration index measured Rainfall Variability. The study established that monthly, seasonal and annual rainfall distribution in Machakos sub County was highly variable, erratic and unpredictable over the 25 years with a CV of 24% and a PCI of 10. There is high temporal rainfall variability (CV of 24% and PCI of 10) in the sub County. Disseminating information on rainfall forecasts, rainwater harvesting for irrigation, proper cattle stocking, a forestation and reforestation programs were highly recommended.

scholarly journals Trend Analysis of Annual and Seasonal River Runoff by Using Innovative Trend Analysis with Significant Test

Water ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 95
Author(s):  
Yilinuer Alifujiang ◽  
Jilili Abuduwaili ◽  
Yongxiao Ge
Keyword(s):  
Time Series ◽  
Trend Analysis ◽  
River Runoff ◽  
Temporal Trends ◽  
Temporal Distribution ◽  
Trend Test ◽  
Data Series ◽  
Mk Test ◽  
Comparison Results ◽  
Innovative Trend Analysis

This study investigated the temporal patterns of annual and seasonal river runoff data at 13 hydrological stations in the Lake Issyk-Kul basin, Central Asia. The temporal trends were analyzed using the innovative trend analysis (ITA) method with significance testing. The ITA method results were compared with the Mann-Kendall (MK) trend test at a 95% confidence level. The comparison results revealed that the ITA method could effectively identify the trends detected by the MK trend test. Specifically, the MK test found that the time series percentage decreased from 46.15% in the north to 25.64% in the south, while the ITA method revealed a similar rate of decrease, from 39.2% to 29.4%. According to the temporal distribution of the MK test, significantly increasing (decreasing) trends were observed in 5 (0), 6 (2), 4 (3), 8 (0), and 8 (1) time series in annual, spring, summer, autumn, and winter river runoff data. At the same time, the ITA method detected significant trends in 7 (1), 9 (3), 6(3), 9 (3), and 8 (2) time series in the study area. As for the ITA method, the “peak” values of 24 time series (26.97%) exhibited increasing patterns, 25 time series (28.09%) displayed increasing patterns for “low” values, and 40 time series (44.94%) showed increasing patterns for “medium” values. According to the “low”, “medium”, and “peak” values, five time series (33.33%), seven time series (46.67%), and three time series (20%) manifested decreasing trends, respectively. These results detailed the patterns of annual and seasonal river runoff data series by evaluating “low”, “medium”, and “peak” values.

Climate change could intensify Sahel conflicts

2022 ◽  
Keyword(s):  
Climate Change ◽  
Security Policy ◽  
Rainfall Variability ◽  
Political Stability ◽  
Climate Impacts ◽  
Small Scale ◽  
Content Type ◽  
Droughts And Floods ◽  
Political Conditions ◽  
Small Scale Irrigation

Significance It will increase rainfall variability and extreme events such as droughts and floods, as well as raising temperatures. These effects may trigger cascading risks to economic, social and political stability. Impacts The EU could play a key role in moderating climate effects as it shapes migration and security policy in the Sahel. The likelihood and severity of climate impacts will depend on socio-economic and political conditions in the region. Small-scale irrigation, climate-adapted seeds and traditional soil conservation techniques can help increase resilience to climate change.

scholarly journals Trend Analysis of Hydroclimatic Variables in the Kamo River Basin, Japan

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1782 ◽  
Author(s):  
Maochuan Hu ◽  
Takahiro Sayama ◽  
Sophal TRY ◽  
Kaoru Takara ◽  
Kenji Tanaka
Keyword(s):  
Trend Analysis ◽  
River Basin ◽  
River Discharge ◽  
Water Resource Management ◽  
Potential Evapotranspiration ◽  
Kendall Test ◽  
Winter Precipitation ◽  
Significant Trend ◽  
Mann Kendall Test ◽  
Proactive Measures

Understanding long-term trends in hydrological and climatic variables is of high significance for sustainable water resource management. This study focuses on the annual and seasonal trends in precipitation, temperature, potential evapotranspiration, and river discharge over the Kamo River basin from the hydrological years 1962 to 2017. Homogeneity was examined by Levene’s test. The Mann–Kendall and a modified Mann–Kendall test as well as Sen’s slope estimator were used to analyze significant trends (p < 0.05) in a time series with and without serial correlation and their magnitudes. The results indicate that potential evapotranspiration calculated by the Penman–Monteith equation was highly related to temperature, and significantly increased in the annual and summer series. Annual river discharge significantly decreased by 0.09 m3/s. No significant trend was found at the seasonal scale. Annual, autumn, and winter precipitation at Kumogahata station significantly increased, while no significant trend was found at Kyoto station. Precipitation was least affected by the modified Mann–Kendall test. Other variables were relatively highly autocorrelated. The modified Mann–Kendall test with a full autocorrelation structure improved the accuracy of trend analysis. Furthermore, this study provides information for decision makers to take proactive measures for sustainable water management.

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