scholarly journals Trends in the Frequency of Intense Precipitation Events in Southern and Southeastern Brazil during 1960–2004

2011 ◽  
Vol 24 (7) ◽  
pp. 1913-1921 ◽  
Author(s):  
Mateus da Silva Teixeira ◽  
Prakki Satyamurty
Keyword(s):  
Extreme Rainfall ◽  
Southeastern Brazil ◽  
Extreme Rainfall Event ◽  
Southern Brazil ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Annual Frequency ◽  
Long Term Trends ◽  
Increasing Trends

Abstract A new approach to define heavy and extreme rainfall events based on cluster analysis and area-average rainfall series is presented. The annual frequency of the heavy and extreme rainfall events is obtained for the southeastern and southern Brazil regions. In the 1960–2004 period, 510 (98) and 466 (77) heavy (extreme) rainfall events are identified in the two regions. Monthly distributions of the events closely follow the monthly climatological rainfall in the two regions. In both regions, annual heavy and extreme rainfall event frequencies present increasing trends in the 45-yr period. However, only in southern Brazil is the trend statistically significant. Although longer time series are necessary to ensure the existence of long-term trends, the positive trends are somewhat alarming since they indicate that climate changes, in terms of rainfall regimes, are possibly under way in Brazil.

scholarly journals ASSESSING THE IMPACTS OF FLOODING CAUSED BY EXTREME RAINFALL EVENTS THROUGH A COMBINED GEOSPATIAL AND NUMERICAL MODELING APPROACH

2016 ◽  
Vol XLI-B8 ◽  
pp. 1271-1278
Author(s):  
J. R. Santillan ◽  
A. M. Amora ◽  
M. Makinano-Santillan ◽  
J. T. Marqueso ◽  
L. C. Cutamora ◽  
...  
Keyword(s):  
Land Cover ◽  
River Basin ◽  
Extreme Rainfall ◽  
Hydrologic Model ◽  
Extreme Rainfall Event ◽  
Hazard Maps ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Modeling Approach ◽  
Flood Depth

In this paper, we present a combined geospatial and two dimensional (2D) flood modeling approach to assess the impacts of flooding due to extreme rainfall events. We developed and implemented this approach to the Tago River Basin in the province of Surigao del Sur in Mindanao, Philippines, an area which suffered great damage due to flooding caused by Tropical Storms Lingling and Jangmi in the year 2014. The geospatial component of the approach involves extraction of several layers of information such as detailed topography/terrain, man-made features (buildings, roads, bridges) from 1-m spatial resolution LiDAR Digital Surface and Terrain Models (DTM/DSMs), and recent land-cover from Landsat 7 ETM+ and Landsat 8 OLI images. We then used these layers as inputs in developing a Hydrologic Engineering Center Hydrologic Modeling System (HEC HMS)-based hydrologic model, and a hydraulic model based on the 2D module of the latest version of HEC River Analysis System (RAS) to dynamically simulate and map the depth and extent of flooding due to extreme rainfall events. The extreme rainfall events used in the simulation represent 6 hypothetical rainfall events with return periods of 2, 5, 10, 25, 50, and 100 years. For each event, maximum flood depth maps were generated from the simulations, and these maps were further transformed into hazard maps by categorizing the flood depth into low, medium and high hazard levels. Using both the flood hazard maps and the layers of information extracted from remotely-sensed datasets in spatial overlay analysis, we were then able to estimate and assess the impacts of these flooding events to buildings, roads, bridges and landcover. Results of the assessments revealed increase in number of buildings, roads and bridges; and increase in areas of land-cover exposed to various flood hazards as rainfall events become more extreme. The wealth of information generated from the flood impact assessment using the approach can be very useful to the local government units and the concerned communities within Tago River Basin as an aid in determining in an advance manner all those infrastructures (buildings, roads and bridges) and land-cover that can be affected by different extreme rainfall event flood scenarios.

scholarly journals Mitigating Toxic Planktonic Cyanobacterial Blooms in Aquatic Ecosystems Facing Increasing Anthropogenic and Climatic Pressures

Toxins ◽  
2018 ◽  
Vol 10 (2) ◽  
pp. 76 ◽  
Author(s):  
Hans Paerl
Keyword(s):  
Climatic Variability ◽  
Extreme Rainfall ◽  
Cyanobacterial Blooms ◽  
Nitrogen And Phosphorus ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Water Diversions ◽  
Short And Long Term ◽  
Reservoir Construction

Toxic planktonic cyanobacterial blooms are a pressing environmental and human health problem. Blooms are expanding globally and threatening sustainability of our aquatic resources. Anthropogenic nutrient enrichment and hydrological modifications, including water diversions and reservoir construction, are major drivers of bloom expansion. Climatic change, i.e., warming, more extreme rainfall events, and droughts, act synergistically with human drivers to exacerbate the problem. Bloom mitigation steps, which are the focus of this review, must consider these dynamic interactive factors in order to be successful in the short- and long-term. Furthermore, these steps must be applicable along the freshwater to marine continuum connecting streams, lakes, rivers, estuarine, and coastal waters. There is an array of physical, chemical, and biological approaches, including flushing, mixing, dredging, application of algaecides, precipitating phosphorus, and selective grazing, that may arrest and reduce bloom intensities in the short-term. However, to ensure long term, sustainable success, targeting reductions of both nitrogen and phosphorus inputs should accompany these approaches along the continuum. Lastly, these strategies should accommodate climatic variability and change, which will likely modulate and alter nutrient-bloom thresholds.

scholarly journals River Flood Hazard Modeling: Forecasting Flood Hazard for Disaster Risk Reduction Planning

2019 ◽  
Vol 5 (11) ◽  
pp. 2309-2317 ◽  
Author(s):  
Murphy Ponce Mohammed
Keyword(s):  
Model Simulation ◽  
Flood Hazard ◽  
Extreme Rainfall ◽  
Base Flow ◽  
Extreme Rainfall Event ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
River Reach ◽  
Analysis System ◽  
Initial Base

The objective of the study is to create a flood hazard model of Tarlac River and to calibrate the model based on data gathered from the Philippine Atmospheric Geophysical and Astronomical Services Administration. The study employed analytical method wherein the 1D flood modeling was utilized. GIS, DEM data, rainfall data, river analysis system, HEC-GeoRAS, hydrologic modeling system, and HEC-GeoHMS were utilized. The different flood models revealed that Tarlac River is not expected to be overtopped by flood water as regards the different extreme rainfall events considered in the present study. The RAS model simulation was based on the concept that there is no base flow observed within the river reach before the occurrence of any extreme rainfall event. Henceforth, there is still no 100 percent assurance that the river reach will not be overtopped with the occurrence of initial base flow in combination with the occurrence of higher extreme rainfall events. Further studies or investigations should be delved into such combination of events. Possible levee breach of the Tarlac River as well as the possible incorporation of flood mitigating interventions in future modeling scenarios can be likewise considered.

scholarly journals Inter-annual precipitation fluctuations alter the responses of above- and belowground biomass to water and N enrichment

2013 ◽  
Vol 10 (8) ◽  
pp. 13427-13454 ◽  
Author(s):  
D. L. Kong ◽  
X. T. Lü ◽  
L. L. Jiang ◽  
H. F. Wu ◽  
Y. Miao ◽  
...  
Keyword(s):  
Annual Variation ◽  
Extreme Rainfall ◽  
Nitrogen Addition ◽  
Rainfall Event ◽  
Annual Precipitation ◽  
Extreme Rainfall Event ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Use Efficiency ◽  
N Enrichment

Abstract. Water availability has profound effects on plant growth and productivity in temperate and semi-arid grasslands. However, it remains unclear how variation of inter-annual precipitation by extreme rainfall events will alter the aboveground and belowground responses of plants, and how these responses may be contingent on N availability. In this study, we examined the interactive effects of inter-annual precipitation variation and N addition on aboveground and live fine root biomass of a semi-arid grassland in northern China for two consecutive years (2007 and 2008). Inter-annual variation in precipitation resulting mainly from the occurrence of extreme rainfall events in 2008 significantly affected above- and belowground plant biomass responses to water addition. In addition, variation of inter-annual precipitation by this extreme rainfall event suppressed plant responses to nitrogen addition and reduced the interaction effects between water and nitrogen addition. These effects of inter-annual precipitation fluctuation could be attributed to the negative influence of the extreme rainfall event on soil N and water availability, ultimately reducing plant rainfall use efficiency and nitrogen use efficiency. In conclusion, our results suggest ecosystem responses to water and N enrichment could be altered by inter-annual variation of precipitation regime caused by the naturally occurring extreme rainfall events.

scholarly journals Extreme rainfall activity in the Australian tropics reflects changes in the El Niño/Southern Oscillation over the last two millennia

2015 ◽  
Vol 112 (15) ◽  
pp. 4576-4581 ◽  
Author(s):  
Rhawn F. Denniston ◽  
Gabriele Villarini ◽  
Angelique N. Gonzales ◽  
Karl-Heinz Wyrwoll ◽  
Victor J. Polyak ◽  
...  
Keyword(s):  
North Atlantic ◽  
El Niño ◽  
El Nino ◽  
Southern Oscillation ◽  
Extreme Rainfall ◽  
El Niño Southern Oscillation ◽  
El Nino Southern Oscillation ◽  
Extreme Rainfall Events ◽  
Rainfall Events

Assessing temporal variability in extreme rainfall events before the historical era is complicated by the sparsity of long-term “direct” storm proxies. Here we present a 2,200-y-long, accurate, and precisely dated record of cave flooding events from the northwest Australian tropics that we interpret, based on an integrated analysis of meteorological data and sediment layers within stalagmites, as representing a proxy for extreme rainfall events derived primarily from tropical cyclones (TCs) and secondarily from the regional summer monsoon. This time series reveals substantial multicentennial variability in extreme rainfall, with elevated occurrence rates characterizing the twentieth century, 850–1450 CE (Common Era), and 50–400 CE; reduced activity marks 1450–1650 CE and 500–850 CE. These trends are similar to reconstructed numbers of TCs in the North Atlantic and Caribbean basins, and they form temporal and spatial patterns best explained by secular changes in the dominant mode of the El Niño/Southern Oscillation (ENSO), the primary driver of modern TC variability. We thus attribute long-term shifts in cyclogenesis in both the central Australian and North Atlantic sectors over the past two millennia to entrenched El Niño or La Niña states of the tropical Pacific. The influence of ENSO on monsoon precipitation in this region of northwest Australia is muted, but ENSO-driven changes to the monsoon may have complemented changes to TC activity.

ANALYSIS OF EXTREME RAINFALL INDICES IN PENINSULAR MALAYSIA

2016 ◽  
Vol 78 (9-4) ◽  
Author(s):  
Nur Shazwani Muhammad ◽  
Amieroul Iefwat Akashah ◽  
Jazuri Abdullah
Keyword(s):  
East Coast ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Peninsular Malaysia ◽  
Rainfall Data ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Daily Rainfall Data ◽  
Extreme Rain ◽  
Increasing Trends

Extreme rainfall events are the main cause of flooding. This study aimed to examine seven extreme rainfall indices, i.e. extreme rain sum (XRS), very wet day intensity (I95), extremely wet day intensity (I99), very wet day proportion (R95), extremely wet day proportion (R99), very wet days (N95) and extremely wet days (N99) using Mann-Kendall (MK) and the normalized statistic Z tests. The analyses are based on the daily rainfall data gathered from Bayan Lepas, Subang, Senai, Kuantan and Kota Bharu. The east coast states received more rainfall than any other parts in Peninsular Malaysia. Kota Bharu station recorded the highest XRS, i.e. 648 mm. The analyses also indicate that the stations in the eastern part of Peninsular Malaysia experienced higher XRS, I95, I99, R95 and R99 as compared to the stations located in the western and northern part of Peninsular Malaysia. Subang and Senai show the highest number of days for wet and very wet (N95) as compared to other stations. Other than that, all stations except for Kota Bharu show increasing trends for most of the extreme rainfall indices. Upward trends indicate that the extreme rainfall events were becoming more severe over the period of 1960 to 2014. 

scholarly journals Extreme rainfall events can alter inter-annual biomass responses to water and N enrichment

2013 ◽  
Vol 10 (12) ◽  
pp. 8129-8138 ◽  
Author(s):  
D. L. Kong ◽  
X. T. Lü ◽  
L. L. Jiang ◽  
H. F. Wu ◽  
Y. Miao ◽  
...  
Keyword(s):  
Annual Variation ◽  
Extreme Rainfall ◽  
Nitrogen Addition ◽  
Rainfall Event ◽  
Annual Precipitation ◽  
Extreme Rainfall Event ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Use Efficiency ◽  
N Enrichment

Abstract. Water availability has profound effects on plant growth and productivity in temperate and semiarid grasslands. However, it remains unclear how variation of inter-annual precipitation by extreme rainfall events will alter the aboveground and belowground responses of plants, and how these responses may be contingent on N availability. In this study, we examined the interactive effects of inter-annual precipitation variation and N addition on aboveground and live fine root biomass of a semiarid grassland in northern China for two consecutive years (2007 and 2008). Inter-annual variation in precipitation resulting mainly from the occurrence of extreme rainfall events in 2008 significantly affected above- and belowground plant biomass responses to water addition. In addition, variation of inter-annual precipitation by this extreme rainfall event suppressed plant responses to nitrogen addition and reduced the interaction effects between water and nitrogen addition. These effects of inter-annual precipitation fluctuation could be attributed to the negative influence of the extreme rainfall event on soil N and water availability, ultimately reducing plant rainfall use efficiency and nitrogen use efficiency. In conclusion, our results suggest ecosystem responses to water and N enrichment could be altered by inter-annual variation of precipitation regime caused by the naturally occurring extreme rainfall events.

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