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

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.

scholarly journals Riverbed Migrations in Western Taiwan under Climate Change

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1631 ◽  
Author(s):  
Yi-Chiung Chao ◽  
Chi-Wen Chen ◽  
Hsin-Chi Li ◽  
Yung-Ming Chen
Keyword(s):  
Climate Change ◽  
21St Century ◽  
Peak Flow ◽  
Extreme Rainfall ◽  
Base Period ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Flow Discharge ◽  
The Future ◽  
The Impact

In recent years, extreme weather phenomena have occurred worldwide, resulting in many catastrophic disasters. Under the impact of climate change, the frequency of extreme rainfall events in Taiwan will increase, according to a report on climate change in Taiwan. This study analyzed riverbed migrations, such as degradation and aggradation, caused by extreme rainfall events under climate change for the Choshui River, Taiwan. We used the CCHE1D model to simulate changes in flow discharge and riverbed caused by typhoon events for the base period (1979–2003) and the end of the 21st century (2075–2099) according to the climate change scenario of representative concentration pathways 8.5 (RCP8.5) and dynamical downscaling of rainfall data in Taiwan. According to the results on flow discharge, at the end of the 21st century, the average peak flow during extreme rainfall events will increase by 20% relative to the base period, but the time required to reach the peak will be 8 h shorter than that in the base period. In terms of the results of degradation and aggradation of the riverbed, at the end of the 21st century, the amount of aggradation will increase by 33% over that of the base period. In the future, upstream sediment will be blocked by the Chichi weir, increasing the severity of scouring downstream. In addition, due to the increased peak flow discharge in the future, the scouring of the pier may be more serious than it is currently. More detailed 2D or 3D hydrological models are necessary in future works, which could adequately address the erosive phenomena created by bridge piers. Our results indicate that not only will flood disasters occur within a shorter time duration, but the catchment will also face more severe degradation and aggradation in the future.

scholarly journals Watershed-Based Rainfall variability and trends of extreme rainfall events in South East Awash Basin, Ethiopia

2019 ◽  
Vol 6 (6) ◽  
pp. 5524-5530
Author(s):  
Yonas Tadesse Alemu
Keyword(s):  
Coefficient Of Variation ◽  
Rainy Season ◽  
Rainfall Variability ◽  
Extreme Rainfall ◽  
Annual Rainfall ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Precipitation Distribution ◽  
Precipitation Concentration ◽  
Dire Dawa

This study presents analysis of Rainfall variability and trends of extreme rainfall events in the Oda Gunufeta -Cherecha -Dechatu watershed, Awash Drainage Basin, Eastern Ethiopia. The study employed the coefficient of variation and the Precipitation Concentration Index (PCI) as statistical descriptors of rainfall variability. The indices at the five stations were subjected to non-parametric Mann-Kendall test to detect the trend over the period between 1985 to 2014. The results of the study revealed that, the watershed experiences moderate inter-annual rainfall variability. The Belg rainfall shows high variability than Kiremt rainfall. Highest Belg & Kiremt rainfall variability is observed in Dire Dawa with coefficient of variation of 46% and 40% respectively. The annual PCI for the watershed in all the stations under investigation during the record periods showed that 100% of the years for which the annual PCI was estimated fell within the irregular precipitation distribution range or high precipitation concentration. The irregular precipitation distribution also extended to all the stations in short rainy season (Belg rainfall) and in two stations in the main rainy season (Kiremt season). With regard to the rainfall trend, the annual rainfall has showed a negative trend in most of the stations for the period 1985-2014. The Mann–Kendall trend test during the Kiremt season shows a positive trend in Dengego, Dire Dawa, Combolcha and Haramaya and the increasing tendency is significant at p<0.1 in Degego, p<0.05 in Dire Dawa, p <0.05 in Combolcha and p <0.01 in Haramaya. The heavy rainfall events, the 90th & 95th percentiles, in all the five stations showed an increasing pattern but except in Combolcha the trends are not statistically significant. This implies that the watershed has been under increased rainfall intensity and this in turn has the potential cause for high risk of flood occurrences.

Tracing seismic landslide-derived sediment dynamics in response to climate change

2021 ◽  
Author(s):  
Jun Xie ◽  
Thomas Coulthard
Keyword(s):  
Climate Change ◽  
Land Surface ◽  
Landscape Evolution ◽  
Mass Movement ◽  
Extreme Rainfall ◽  
Channel Network ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Seismic Landslide ◽  
The Impact

&lt;p&gt;Mass movement such as landslides and rock fall is a prominent source of sediment in active mountain belt. Earthquake triggered landslides can generate substantial loose sediment and have significant geomorphic effects on long term landscape evolution. More importantly, these landslide impacts to land surface vary a lot due to the divergence of landslide characteristics and surrounding environment settings. Downslope and downstream transport of sediment into the channel network is fairly sensitive to climatic perturbations especially for extreme rainfall events. A wide variety of studies attempt to quantify or determine the contribution of landslide generated material to gross sediment budget and the corresponding retention time scale of landslide generated deposit in the mountain basin, whereas no established techniques can explicitly fingerprint/track landslide derived sediment. In this study, we first generated the hourly future extreme rainfall under two emission scenario (RCP4.5, RCP8.5) using &amp;#8216;NASA Earth Exchange Global Daily Downscaled Projections (NEX-GDDP)&amp;#8217; dataset. A new tracing function is incorporated into CAESAR-lisflood to track the landslide derived sediment footprint and dynamics in response to climate change. The landscape evolution at the Hongxi catchment, which is suffered tremendous damage from Wenchuan earthquake (Ms 8.0), are then simulated using CAESAR-lisflood under two climate scenarios. The results show that more than 80 percent of material generated by seismic landslides are still retained at the hillslope even after a sufficient time (e.g. 100 year). This study is to compare the spatial-temporal evolution pattern of landslides-derived sediment under two climatic scenarios (RCP4.5, RCP8.5), thus probing into the landslide generated sediment transport and budget respond to the climate change especially the impact of extreme rainfall events. Numerical modelling can provide a quick and effective tool for broad scale predictions of sediment produced by landslide events under different climatic predictions, which is of great importance for seismic induced disaster protection and reduction under climate change.&lt;/p&gt;

Changes in grassland ecosystem function due to extreme rainfall events: implications for responses to climate change

2008 ◽  
Vol 14 (7) ◽  
pp. 1600-1608 ◽  
Author(s):  
PHILIP A. FAY ◽  
DAWN M. KAUFMAN ◽  
JESSE B. NIPPERT ◽  
JONATHAN D. CARLISLE ◽  
CHRISTOPHER W. HARPER
Keyword(s):  
Climate Change ◽  
Ecosystem Function ◽  
Extreme Rainfall ◽  
Grassland Ecosystem ◽  
Extreme Rainfall Events ◽  
Rainfall Events

scholarly journals Evaluation of climate change impacts on extreme rainfall events characteristics using a synoptic weather typing-based daily precipitation downscaling model

2017 ◽  
Vol 8 (3) ◽  
pp. 388-411 ◽  
Author(s):  
Hamed Tavakolifar ◽  
Ebrahim Shahghasemi ◽  
Sara Nazif
Keyword(s):  
Climate Change ◽  
General Circulation ◽  
Daily Precipitation ◽  
Extreme Event ◽  
Climate Change Impacts ◽  
Extreme Rainfall ◽  
Extreme Rainfall Events ◽  
Study Region ◽  
Rainfall Events ◽  
Synoptic Weather Typing

Climate change has impacted all phenomena in the hydrologic cycle, especially extreme events. General circulation models (GCMs) are used to investigate climate change impacts but because of their low resolution, downscaling methods are developed to provide data with high enough resolution for regional studies from GCM outputs. The performance of rainfall downscaling methods is commonly acceptable in preserving average characteristics, but they do not preserve the extreme event characteristics especially rainfall amount and distribution. In this study, a novel downscaling method called synoptic statistical downscaling model is proposed for daily precipitation downscaling with an emphasis on extreme event characteristics preservation. The proposed model is applied to a region located in central Iran. The results show that the developed model can downscale all percentiles of precipitation events with an acceptable performance and there is no assumption about the similarity of future rainfall data with the historical observations. The outputs of CCSM4 GCM for two representative concentration pathways (RCPs) of RCP4.5 and RCP8.5 are used to investigate the climate change impacts in the study region. The results show 40% and 30% increase in the number of extreme rainfall events under RCP4.5 and RCP8.5, respectively.

scholarly journals Risks of seasonal extreme rainfall events in Bangladesh under 1.5 and 2.0 degrees’ warmer worlds – How anthropogenic aerosols change the story

2018 ◽  
Author(s):  
Ruksana H. Rimi ◽  
Karsten Haustein ◽  
Emily J. Barbour ◽  
Sarah N. Sparrow ◽  
Sihan Li ◽  
...  
Keyword(s):  
Climate Change ◽  
Global Warming ◽  
Climate Model ◽  
Substantial Reduction ◽  
Extreme Rainfall ◽  
Extreme Weather Events ◽  
Future Climate Change ◽  
Anthropogenic Aerosols ◽  
Extreme Rainfall Events ◽  
Rainfall Events

Abstract. Anthropogenic climate change is likely to increase the frequency of extreme weather events in future. Previous studies have robustly shown how and where climate change has already changed the risks of weather extremes. However, developing countries have been somewhat underrepresented in these studies, despite high vulnerability and limited capacities to adapt. How additional global warming would affect the future risks of extreme rainfall events in Bangladesh needs to be addressed to limit adverse impacts. Our study focuses on understanding and quantifying the relative risks of seasonal extreme rainfall events in Bangladesh under the Paris Agreement temperature goals of 1.5 °C and 2 °C warming above pre-industrial levels. In particular, we investigate the influence of anthropogenic aerosols on these risks given their likely future reduction and resulting amplification of global warming. Using large ensemble regional climate model simulations from weather@home under different forcing scenarios, we compare the risks of rainfall events under pre-industrial (natural), current (actual), 1.5 °C, and 2.0 °C warmer and greenhouse gas only (anthropogenic aerosols removed) conditions. We find that the risk of a 1 in 100 year rainfall event has already increased significantly compared with pre-industrial levels across parts of Bangladesh, with additional increases likely for 1.5 and 2.0 degree warming (of up to 5.5 times higher, with an uncertainty range of 3.5 to 7.8 times). Impacts were observed during both the pre-monsoon and monsoon periods, but were spatially variable across the country in terms of the level of impact. Results also show that reduction in anthropogenic aerosols plays an important role in determining the overall future climate change impacts; by exacerbating the effects of GHG induced global warming and thereby increasing the rainfall intensity. We highlight that the net aerosol effect varies from region to region within Bangladesh, which leads to different outcomes of aerosol reduction on extreme rainfall statistics, and must therefore be considered in future risk assessments. Whilst there is a substantial reduction in the impacts resulting from 1.5 °C compared with 2 °C warming, the difference is spatially and temporally variable, specifically with respect to seasonal extreme rainfall events.

Fire and rain are one: extreme rainfall events predict wildfire extent in an arid grassland

2020 ◽  
Vol 29 (8) ◽  
pp. 702 ◽  
Author(s):  
Elise M. Verhoeven ◽  
Brad R. Murray ◽  
Chris R. Dickman ◽  
Glenda M. Wardle ◽  
Aaron C. Greenville
Keyword(s):  
Landsat Imagery ◽  
Extreme Rainfall ◽  
Environmental Drivers ◽  
Annual Rainfall ◽  
Extreme Rainfall Events ◽  
Study Region ◽  
Rainfall Events ◽  
The North ◽  
The Mean ◽  
Wildfire Regimes

Assessing wildfire regimes and their environmental drivers is critical for effective land management and conservation. We used Landsat imagery to describe the wildfire regime of the north-eastern Simpson Desert (Australia) between 1972 and 2014, and to quantify the relationship between wildfire extent and rainfall. Wildfires occurred in 15 of the 42 years, but only 27% of the study region experienced multiple wildfires. A wildfire in 1975 burned 43% of the region and is the largest on record for the area. More recently, a large wildfire in 2011 reburned areas that had not burned since 1975 (47% of the 2011 wildfire), as well as new areas that had no record of wildfires (25% of the 2011 wildfire). The mean minimum wildfire return interval was 27 years, comparable with other spinifex-dominated grasslands, and the mean time since last wildfire was 21 years. Spinifex-dominated vegetation burned most frequently and over the largest area. Extreme annual rainfall events (&gt; 93rd percentile) effectively predicted large wildfires occurring 2 years after those events. Extreme rainfall is predicted to increase in magnitude and frequency across central Australia, which could alter wildfire regimes and have unpredictable and far-reaching effects on ecosystems in the region’s arid landscapes.

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