scholarly journals Characteristics, Origins, and Impacts of Summertime Extreme Precipitation in the Lake Mead Watershed

2020 ◽  
Vol 33 (7) ◽  
pp. 2663-2680 ◽  
Author(s):  
Michael D. Sierks ◽  
Julie Kalansky ◽  
Forest Cannon ◽  
F. M. Ralph
Keyword(s):  
North American ◽  
Extreme Precipitation ◽  
Extreme Rainfall ◽  
North American Monsoon ◽  
Lake Mead ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
The North ◽  
The U.S ◽  
Tier I

AbstractThe North American monsoon (NAM) is the main driver of summertime climate variability in the U.S. Southwest. Previous studies of the NAM have primarily focused on the Tier I region of the North American Monsoon Experiment (NAME), spanning central-western Mexico, southern Arizona, and New Mexico. This study, however, presents a climatological characterization of summertime precipitation, defined as July–September (JAS), in the Lake Mead watershed, located in the NAME Tier II region. Spatiotemporal variability of JAS rainfall is examined from 1981 to 2016 using gridded precipitation data and the meteorological mechanisms that account for this variability are investigated using reanalyses. The importance of the number of wet days (24-h rainfall ≥1 mm) and extreme rainfall events (95th percentile of wet days) to the total JAS precipitation is examined and shows extreme events playing a larger role in the west and central basin. An investigation into the dynamical drivers of extreme rainfall events indicates that anticyclonic Rossby wave breaking (RWB) in the midlatitude westerlies over the U.S. West Coast is associated with 89% of precipitation events >10 mm (98th percentile of wet days) over the Lake Mead basin. This is in contrast to the NAME Tier I region where easterly upper-level disturbances such as inverted troughs are the dominant driver of extreme precipitation. Due to the synoptic nature of RWB events, corresponding impacts and hazards extend beyond the Lake Mead watershed are relevant for the greater U.S. Southwest.

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 (> 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.

Watershed Hydrological and Chemical Responses to Precipitation Variability in the Luquillo Mountains of Puerto Rico

2003 ◽  
Author(s):  
Douglas Schaefer
Keyword(s):  
Puerto Rico ◽  
Extreme Events ◽  
Extreme Rainfall ◽  
Precipitation Variability ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Tropical Regions ◽  
The North ◽  
Temperature And Precipitation ◽  
The North Atlantic

Variations in temperature and precipitation are both components of climate variability. Based on coral growth rates measured near Puerto Rico, the Caribbean was 2–3ºC cooler during the “Little Ice Age” during the seventeenth century (Winter et al. 2000). At the millennial scale, temperature variations in tropical regions have been inferred to have substantial biological effects (such as speciation and extinction), but not at the multidecadal timescales considered here. My focus is on precipitation variability in particular, because climate models examining effects of increased greenhouse gases suggest greater changes in precipitation than in temperature patterns in tropical regions. Some correspondence between both the El Niño–Southern Oscillation (ENSO) and the Northern Atlantic Oscillation (NAO) and average temperatures and total annual precipitation have been reported for the LTER site at Luquillo (Greenland 1999; Greenland and Kittel 2002), but those studies did not refer to extreme events. Based on climate records for Puerto Rico since 1914, Malmgren et al. (1997) found small increases in air temperature during El Niño years and somewhat greater total rainfall during the positive phase of the NAO. Similar to ENSO, the NAO index is characterized by differences in sea-level atmospheric pressure, in this case based on measurements in Iceland and Portugal (Walker and Bliss 1932). Its effects on climate have largely been described in terms of temperature and precipitation anomalies in countries bordering the North Atlantic (e.g., Hurrell 1995). Puerto Rico is in the North Atlantic hurricane zone, and hurricanes clearly play a major role in precipitation variability. The association between extreme rainfall events and hurricanes is discussed in detail in this chapter. I examine the degree to which extreme rainfall events are associated with hurricanes and other tropical storms. I discuss whether the occurrence of these extreme events has changed through time in Puerto Rico or can be linked to the recurrent patterns of the ENSO or the NAO. I examine the 25-year daily precipitation record for the Luquillo LTER site, the 90-year monthly record from the nearest site to Luquillo with such a long record, Fajardo, and those of the two other Puerto Rico stations with the longest daily precipitation records, Manati and Mayaguez (figure 8.1).

scholarly journals Determinação da curva de intensidade-duração-frequência do município de Cruzeiro do Sul – Acre

2021 ◽  
Vol 43 ◽  
pp. e30
Author(s):  
Nayara Dos Santos Albrigo ◽  
Maylla Tawanda dos Santos Pereira ◽  
Nelma Tavares Dias Soares ◽  
Gleibson De Souza Andrade ◽  
Vinicius Alexandre Sikora de Souza ◽  
...  
Keyword(s):  
Gumbel Distribution ◽  
Extreme Rainfall ◽  
Return Time ◽  
Good Adherence ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
The North ◽  
Historical Series ◽  
Intensity Duration Frequency ◽  
Engineering Projects

Information on extreme rainfall events associated with predictability and probabilities, especially in intensity-duration-frequency (IDF) curves, are essential for the development of engineering projects aimed at sanitation, drainage and waterproofing of surfaces, which allow to offer more suitable conditions for dimensioning hydraulic and hydrological works and services. However, much of the North Region of the country does not have this information available or updated. Thus, the objective of this study was to develop the IDF equation for the municipality of Cruzeiro do Sul - AC. A 14-year historical series was used, distributed between 1993 and 2011, such data were analyzed by the Gumbel distribution, the same being related, by means of the daily rain breakdown, for return periods comprising 2 to 100 years and rainfall durations of 5 minutes to 24 hours. In the analysis for the construction of the curve, it was observed that the years 1995 and 2002 corresponded to the years with the highest precipitated height indexes, being 111 mm and 103 mm, respectively, however these events had an estimated return time between 3 and 8 years, which does not denote anomalous events. The IDF curve constructed in the study showed good adherence to the observed data, which proves its use in the region.

scholarly journals UAV-based evaluation of morphological changes induced by extreme rainfall events in meandering rivers

PLoS ONE ◽  
2020 ◽  
Vol 15 (11) ◽  
pp. e0241293
Author(s):  
Semih Sami Akay ◽  
Orkan Özcan ◽  
Füsun Balık Şanlı ◽  
Tolga Görüm ◽  
Ömer Lütfi Şen ◽  
...  
Keyword(s):  
Water Level ◽  
Extreme Precipitation ◽  
Morphological Changes ◽  
Extreme Rainfall ◽  
Precipitation Event ◽  
River Channels ◽  
Meandering Rivers ◽  
Erosion And Deposition ◽  
Extreme Rainfall Events ◽  
Rainfall Events

Morphological changes, caused by the erosion and deposition processes due to water discharge and sediment flux occur, in the banks along the river channels and in the estuaries. Flow rate is one of the most important factors that can change river morphology. The geometric shapes of the meanders and the river flow parameters are crucial components in the areas where erosion or deposition occurs in the meandering rivers. Extreme precipitation triggers erosion on the slopes, which causes significant morphological changes in large areas during and after the event. The flow and sediment amount observed in a river basin with extreme precipitation increases and exceeds the long-term average value. Hereby, erosion severity can be determined by performing spatial analyses on remotely sensed imagery acquired before and after an extreme precipitation event. Changes of erosion and deposition along the river channels and overspill channels can be examined by comparing multi-temporal Unmanned Aerial Vehicle (UAV) based Digital Surface Model (DSM) data. In this study, morphological changes in the Büyük Menderes River located in the western Turkey, were monitored with pre-flood (June 2018), during flood (January 2019), and post-flood (September 2019) UAV surveys, and the spatial and volumetric changes of eroded/deposited sediment were quantified. For this purpose, the DSAS (Digital Shoreline Analysis System) method and the DEM of Difference (DoD) method were used to determine the changes on the riverbank and to compare the periodic volumetric morphological changes. Hereby, Structure from Motion (SfM) photogrammetry technique was exploited to a low-cost UAV derived imagery to achieve riverbank, areal and volumetric changes following the extreme rainfall events extracted from the time series of Tropical Rainfall Measuring Mission (TRMM) satellite data. The change analyses were performed to figure out the periodic morphodynamic variations and the impact of the flood on the selected meandering structures. In conclusion, although the river water level increased by 0.4–5.9 meters with the flood occurred in January 2019, the sediment deposition areas reformed after the flood event, as the water level decreased. Two-year monitoring revealed that the sinuosity index (SI) values changed during the flood approached the pre-flood values over time. Moreover, it was observed that the amount of the deposited sediments in September 2019 approached that of June 2018.

scholarly journals Impact of extreme precipitation and water table change on N<sub>2</sub>O fluxes in a bio-energy poplar plantation

2011 ◽  
Vol 8 (2) ◽  
pp. 2057-2092 ◽  
Author(s):  
D. Zona ◽  
I. A. Janssens ◽  
M. S. Verlinden ◽  
L. S. Broeckx ◽  
J. Cools ◽  
...  
Keyword(s):  
Wind Speed ◽  
Extreme Precipitation ◽  
Pore Space ◽  
Large Fraction ◽  
Extreme Rainfall ◽  
N2o Emission ◽  
N2o Emissions ◽  
N2o Production ◽  
Extreme Rainfall Events ◽  
Rainfall Events

Abstract. A large fraction of the West European landscape is used for intensive agriculture. Several of these countries have very high nitrous oxide (N2O) emissions, because of substantial use of fertilizers and high rates of atmospheric nitrogen deposition. N2O production in soils is controlled by water-filled pore space (WFPS) and substrate availability (NO3). Here we show that extreme precipitation (80 mm rainfall in 48 h) after a long dry period, led to a week-long peak in N2O emissions (up to about 2200 μg N2O-N m−2 h−1). In the first four of these peak emission days, N2O fluxes showed a pronounced diurnal pattern correlated to daytime increase in temperature and wind speed. It is possible that N2O was transported through the transpiration stream of the poplar trees and emitted through the stomates. However, during the following three high emission days, N2O emission was fairly stable with no pronounced diurnal trend, and was correlated with wind speed and WFPS (at 20 and 40 cm depth) but no longer with soil temperature. We hypothesized that wind speed facilitated N2O emission from the soil to the atmosphere through a significant pressure-pumping. Successive rainfall events and similar WFPS after this first intense precipitation did not lead to N2O emissions of the same magnitude. These findings suggest that climate change-induced modification in precipitation patterns may lead to high N2O emission pulses from soil, such that sparser and more extreme rainfall events after longer dry periods could lead to peak N2O emissions. The cumulative effects of more variable climate on annual N2O emission are still largely uncertain and need further investigation.

Precipitation extremes over southern South America and their synoptic environment in a set of CORDEX regional climate models

2021 ◽  
Author(s):  
Matias Ezequiel Olmo ◽  
Maria Laura Bettolli
Keyword(s):  
South America ◽  
Extreme Precipitation ◽  
Climate Models ◽  
Regional Climate ◽  
Extreme Rainfall ◽  
Regional Climate Models ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Circulation Types ◽  
Observational Uncertainty

&lt;p&gt;Southern South America (SSA) is a wide populated region exposed to extreme rainfall events, which are recognised as some of the major threats in a warming climate. These events produce large impacts on socio-economic activities, energy demand and health systems. Hence, studying this phenomena requires high-quality and high-resolution observational data and model simulations. In this work, the main features of daily extreme precipitation and circulation types over SSA were evaluated using a 4-model set of CORDEX regional climate models (RCMs) driven by ERA-Interim during 1980-2010: RCA4 and WRF from CORDEX Phase 1 and RegCM4v7 and REMO2015 from the brand-new CORDEX-CORE simulations. Observational uncertainty was assessed by comparing model outputs with multiple observational datasets (rain gauges, CHIRPS, CPC and MSWEP).&amp;#160;&lt;/p&gt;&lt;p&gt;The inter-comparison of extreme events, characterized in terms of their intensity, frequency and spatial coverage, varied across SSA exhibiting large differences among observational datasets and RCMs, pointing out the current observational uncertainty when evaluating precipitation extremes, particularly at a daily scale. The spread between observational datasets was smaller than for the RCMs. Most of the RCMs successfully captured the spatial pattern of extreme rainfall across SSA, reproducing the maximum intensities in southeastern South America (SESA) and central and southern Chile during the austral warm (October to March) and cold (April to September) seasons, respectively. However, they often presented overestimations over central and southern Chile, and more variable results in SESA. RegCM4 and WRF seemed to well represent the maximum precipitation amounts over SESA, while REMO showed strong overestimations and RCA4 had more difficulties in representing the spatial distribution of heavy rainfall intensities. Focusing over SESA, differences were detected in the timing and location of extremes (including the areal coverage) among both observational datasets and RCMs, which poses a particular challenge when performing impact studies in the region. Thus, stressing that the use of multiple datasets is of key importance when carrying out regional climate studies and model evaluations, particularly for extremes.&amp;#160;&lt;/p&gt;&lt;p&gt;The synoptic environment was described by a classification of circulation types (CTs) using Self-Organizing Maps (SOM) considering geopotential height anomalies at 500 hPa (Z500). Specific CTs were identified as they significantly enhanced the occurrence of extreme rainfall events in sectorized areas of SESA. In particular, a dipolar structure of Z500 anomalies that produced a marked trough at the mid-level atmosphere, usually located east of the Andes, significantly favoured the occurrence of extreme precipitation events in the warm season. The RCMs were able to adequately reproduce the SOM frequencies, although simplifying the predominant CTs into a reduced number of configurations. They appropriately reproduced the observed extreme precipitation frequencies conditioned by the CTs and their atmospheric configurations, but exhibiting some limitations in the location and intensity of the resulting precipitation systems.&lt;/p&gt;&lt;p&gt;In this sense, continuous evaluations of observational datasets and model simulations become necessary for a better understanding of the physical mechanisms behind extreme precipitation over the region, as well as for its past and future changes in a climate change scenario.&lt;/p&gt;

Isotopic variability (δ18O, δ2H and d-excess) during rainfall events of the north American monsoon across the Sonora River Basin, Mexico

2021 ◽  
Vol 105 ◽  
pp. 102928
Author(s):  
Juan Pérez Quezadas ◽  
David Adams ◽  
Ricardo Sánchez Murillo ◽  
Alejandro Jiménez Lagunes ◽  
José Luis Rodríguez Castañeda
Keyword(s):  
River Basin ◽  
North American ◽  
North American Monsoon ◽  
Rainfall Events ◽  
The North

scholarly journals Long-Term Temporal Variation of Extreme Rainfall Events in Australia: 1910–2006

2010 ◽  
Vol 11 (4) ◽  
pp. 950-965 ◽  
Author(s):  
Guobin Fu ◽  
Neil R. Viney ◽  
Stephen P. Charles ◽  
Jianrong Liu
Keyword(s):  
Temporal Variation ◽  
Extreme Events ◽  
Extreme Precipitation ◽  
Southern Oscillation ◽  
Extreme Rainfall ◽  
Temporal Variations ◽  
Recurrence Interval ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Extreme Precipitation Events

Abstract The temporal variability of the frequency of short-duration extreme precipitation events in Australia for the period 1910–2006 is examined using the high-quality rainfall dataset identified by the Bureau of Meteorology, Australia, for 189 stations. Extreme events are defined by duration and recurrence interval: 1, 5, 10, and 30 days, and 1, 5, and 20 yr, respectively. The results indicate that temporal variations of the extreme precipitation index (EPI) for various durations and recurrence intervals in the last 100 yr, except for the low frequencies before 1918, have experienced three U-shaped cycles: 1918–53, 1953–74, and 1974–2006. Seasonal results indicate that about two-thirds of 1-day, 1-yr recurrence interval extreme events occur from December to March. Time series of anomalies of the regional EPIs for four regions indicate that northeast Australia and southeast Australia have almost the same temporal variation as the national anomalies, South Australia experienced a negative anomaly of extreme rainfall events in the mid-1950s, and southwest Western Australia (SWWA) experienced relatively small temporal variation. The relationships between extreme rainfall events and the Southern Oscillation index (SOI) and the interdecadal Pacific oscillation (IPO) indicate that extreme rainfall events in Australia have a strong relationship with both, especially during La Niña years and after 1942.

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