Two-dimensional numerical modeling of sediment transport in a dam reservoir to analyze the feasibility of a water intake

The present work is related to the study of a water intake projected into a dam reservoir, located in northern Morocco. The object sought is to examine the natural conditions surrounding a water intake and their possible repercussions on its operation. Thus, a two-dimensional numerical model is developed to simulate the sediment transport in a reservoir dam. The developed model consists of hydrodynamic module based on the Saint–Venant equations and sediment transport module based on the mass-balance equation, where there are resolved by a MacCormack numerical scheme and upwind scheme, respectively. The analysis using the numerical model has made it possible to predict the shutdown periods of the drinking water production station with respect to the rate of suspended solids (SS) for extreme rainfall events.

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Hydro-geomorphological response to changes in the spatial structure of extreme rainfall in a warmer world

10.5194/egusphere-egu2020-1563 ◽

2020 ◽

Author(s):

Nadav Peleg ◽

Chris Skinner ◽

Simone Fatichi ◽

Peter Molnar

Keyword(s):

Sediment Transport ◽

Spatial Structure ◽

Extreme Rainfall ◽

Climate Impacts ◽

Small Scale ◽

Runoff Generation ◽

Extreme Rainfall Events ◽

Rainfall Events ◽

Sediment Yields ◽

Rainfall Volume

<p>Spatial characteristics of extreme rainfall are expected to change with increasing temperatures. Extreme rainfall directly affects streamflow and sediment transport volumes and peaks, yet the effect of climate change on the small-scale spatial structure of extreme rainfall and subsequent impacts on hydrology and geomorphology remain largely unexplored. Motivated by this knowledge gap, we conducted a numerical experiment in which synthetic rainfall fields representing extreme rainfall events of two types, stratiform and convective, were simulated using a space-time rainfall generator model (AWE-GEN-2d). The rainfall fields were modified to follow different spatial rainfall scenarios, associated with increasing temperatures, and used as inputs into a landscape evolution model (CAESAR-Lisflood). We found that the response of the streamflow and sediment yields are highly sensitive to changes in total rainfall volume and to a lesser extent to changes in localized peak rainfall intensities. The morphological (erosion and sediment transport) components were found to be more sensitive to changes in rainfall spatial structure in comparison to the hydrological components, and more sensitive to convective rainfall than stratiform rainfall because of localized runoff generation and erosion production. In addition, we showed that assuming extreme rainfall events to intensify with increasing temperatures without introducing a change in the rainfall spatial structure might lead to over-estimation of future climate impacts on basin-wide hydro-geomorphology.</p>

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A Numerical Model Study of an Intense Cutoff Low Pressure System over South Africa

Monthly Weather Review ◽

10.1175/mwr3311.1 ◽

2007 ◽

Vol 135 (3) ◽

pp. 1128-1150 ◽

Cited By ~ 52

Author(s):

A. T. Singleton ◽

C. J. C. Reason

Keyword(s):

South Africa ◽

Numerical Model ◽

Extreme Rainfall ◽

South Coast ◽

African Region ◽

Extreme Rainfall Events ◽

Rainfall Events ◽

Low Level ◽

Southern African Region ◽

Cutoff Low

Abstract Investigations of extreme rainfall events in the southern African region are limited by the paucity of the observational network. Furthermore, the lack of full radar coverage for South Africa makes quantitative precipitation estimation difficult. Therefore, numerical modeling represents the most effective method for improving the understanding of the mechanisms that contribute to extreme rainfall events in this region with the caveat that accurate validation of model simulations is hampered by the limited observations in the region. This paper describes an intense cutoff low event over South Africa that led to record rainfall and flash flooding along the south coast of the country and adjoining hinterland. Analyses from the Global Forecast System model showed that the cutoff aloft was accompanied by a strong low-level jet (LLJ) impinging onto the south coast where rainfall was heaviest, and that lapse rates were steep in the lower troposphere. Simulations of the event were carried out using a numerical model [i.e., the fifth-generation Pennsylvania State University–National Center for Atmospheric Research Mesoscale Model (MM5)], which showed that severe convection occurred over the ocean on the right-hand side of the LLJ, and at its leading edge where it impinged on the coastal topography. This topography was also very important in providing additional forcing for the ascent of moist air. A factor separation technique was used to show that surface heat fluxes from the warm sea surface temperature (SST) of the Agulhas Current were important in enhancing low-level cyclogenesis, and that topography was important in maintaining the position of the low-level coastal depression, which led to favorable conditions for rainfall remaining in the same area for an extended period of time. It is suggested that improved representation of the tight topographic and SST gradients of the southern African region in NWP models or postprocessing systems would help to provide more accurate forecasts of the amount and location of heavy precipitation during cutoff low events where surface forcing is important.

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The Influence of Geographical Factors on Extreme Rainfalls in Lampung Province

Journal of Engineering and Scientific Research ◽

10.23960/jesr.v1i1.7 ◽

2019 ◽

Vol 1 (1) ◽

pp. 33

Author(s):

M Welly

Keyword(s):

Geographical Location ◽

Daily Rainfall ◽

Extreme Rainfall ◽

Design Flood ◽

Extreme Rainfall Events ◽

Rainfall Events ◽

Ungauged Basin ◽

Flood Discharge ◽

Design Rainfall ◽

Geographical Factors

Many people in Indonesia calculate design rainfall before calculating the design flooddischarge. The design rainfall with a certain return period will eventually be convertedinto a design flood discharge by combining it with the characteristics of the watershed.However, the lack of a network of rainfall recording stations makes many areas that arenot hydrologically measured (ungauged basin), so it is quite difficult to know thecharacteristics of rain in the area concerned. This study aims to analyze thecharacteristics of design rainfall in Lampung Province. The focus of the analysis is toinvestigate whether geographical factors influence the design rainfall that occurs in theparticular area. The data used in this study is daily rainfall data from 15 rainfallrecording stations spread in Lampung Province. The method of frequency analysis usedin this study is the Gumbel method. The research shows that the geographical location ofan area does not have significant effect on extreme rainfall events. The effect of risingearth temperatures due to natural exploitation by humans tends to be stronger as a causeof extreme events such as extreme rainfall.Keywords: Influence, geographical, factors, extreme, rainfall.

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CLIMATOLOGY OF EXTREME RAINFALL EVENTS IN EASTERN AND NORTHERN SANTA CATARINA STATE, BRAZIL: PRESENT AND FUTURE CLIMATE

Brazilian Journal of Geophysics ◽

10.22564/rbgf.v31i3.314 ◽

2013 ◽

Vol 31 (3) ◽

pp. 413 ◽

Cited By ~ 3

Author(s):

André Becker Nunes ◽

Gilson Carlos Da Silva

Keyword(s):

Climate Model ◽

Climate Modeling ◽

Linear Trend ◽

Extreme Rainfall ◽

Eastern Region ◽

Santa Catarina ◽

Extreme Rainfall Events ◽

Rainfall Events ◽

History Of ◽

Santa Catarina State

ABSTRACT. The eastern region of Santa Catarina State (Brazil) has an important history of natural disasters due to extreme rainfall events. Floods and landslides are enhancedby local features such as orography and urbanization: the replacement of natural surface coverage causing more surface runoff and, hence, ﬂooding. Thus, studies of this type of events – which directly inﬂuence life in the towns – take on increasing importance. This work makes a quantitative analysis of occurrences of extreme rainfall events in the eastern and northern regions of Santa Catarina State in the last 60 years, through individual analysis, considering the history of ﬂoods ineach selected town, as well as an estimate through to the end of century following regional climate modeling. A positive linear trend, in most of the towns studied, was observed in the results, indicating greater frequency of these events in recent decades, and the HadRM3P climate model shows a heterogeneous increase of events for all towns in the period from 2071 to 2100.Keywords: ﬂoods, climate modeling, linear trend. RESUMO. A região leste do Estado de Santa Catarina tem um importante histórico de desastres naturais ocasionados por eventos extremos de precipitação. Inundações e deslizamentos de terra são potencializados pelo relevo acidentado e pela urbanização das cidades da região: a vegetação nativa vem sendo removida acarretando um maior escoamento superﬁcial e, consequentemente, em inundações. Desta forma, torna-se de suma importância os estudos acerca deste tipo de evento que inﬂuencia diretamente a sociedade em geral. Neste trabalho é realizada uma análise quantitativa do número de eventos severos de precipitação ocorridos nas regiões leste e norte de Santa Catarina dos últimos 60 anos, por meio de uma análise pontual, considerandoo histórico de inundações de cada cidade selecionada, além de uma projeção para o ﬁm do século de acordo com modelagem climática regional. Na análise dos resultados observou-se uma tendência linear positiva na maioria das cidades, indicando uma maior frequência deste tipo de evento nas últimas décadas, e o modelo climático HadRM3P mostra um aumento heterogêneo no número de eventos para todas as cidades no período de 2071 a 2100.Palavras-chave: inundações, modelagem climática, tendência linear.

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IDENTIFICATION OF EXTREME RAINFALL EVENTS USING HIGH-RESOLUTION CARBON ISOTOPE MEASUREMENTS ACROSS TREE-RINGS

10.1130/abs/2017am-306100 ◽

2017 ◽

Author(s):

Rose G. Telus ◽

◽

Brian A. Schubert

Keyword(s):

High Resolution ◽

Carbon Isotope ◽

Tree Rings ◽

Extreme Rainfall ◽

Extreme Rainfall Events ◽

Rainfall Events ◽

Isotope Measurements

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Comparing vulnerability and institutional capacities in three Latin American coastal localities in response to extreme rainfall events

Journal of Coastal Conservation ◽

10.1007/s11852-020-00790-4 ◽

2021 ◽

Vol 25 (1) ◽

Author(s):

Arturo Ruiz-Luna ◽

Claudia Martínez-Peralta ◽

Patricia P. B. Eichler ◽

Leonardo R. Teixeira ◽

Montserrat Acosta-Morel ◽

...

Keyword(s):

Latin American ◽

Extreme Rainfall ◽

Extreme Rainfall Events ◽

Rainfall Events

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Tropical cyclone contribution to extreme rainfall over southwest Pacific Island nations

Climate Dynamics ◽

10.1007/s00382-021-05680-5 ◽

2021 ◽

Author(s):

Anil Deo ◽

Savin S. Chand ◽

Hamish Ramsay ◽

Neil J. Holbrook ◽

Simon McGree ◽

...

Keyword(s):

Tropical Cyclone ◽

El Niño ◽

El Nino ◽

Extreme Rainfall ◽

Pacific Island ◽

Extreme Rainfall Events ◽

Rainfall Events ◽

Southwest Pacific ◽

Inactive Phase ◽

Pacific Island Nations

AbstractSouthwest Pacific nations are among some of the worst impacted and most vulnerable globally in terms of tropical cyclone (TC)-induced flooding and accompanying risks. This study objectively quantifies the fractional contribution of TCs to extreme rainfall (hereafter, TC contributions) in the context of climate variability and change. We show that TC contributions to extreme rainfall are substantially enhanced during active phases of the Madden–Julian Oscillation and by El Niño conditions (particularly over the eastern southwest Pacific region); this enhancement is primarily attributed to increased TC activity during these event periods. There are also indications of increasing intensities of TC-induced extreme rainfall events over the past few decades. A key part of this work involves development of sophisticated Bayesian regression models for individual island nations in order to better understand the synergistic relationships between TC-induced extreme rainfall and combinations of various climatic drivers that modulate the relationship. Such models are found to be very useful for not only assessing probabilities of TC- and non-TC induced extreme rainfall events but also evaluating probabilities of extreme rainfall for cases with different underlying climatic conditions. For example, TC-induced extreme rainfall probability over Samoa can vary from ~ 95 to ~ 75% during a La Niña period, if it coincides with an active or inactive phase of the MJO, and can be reduced to ~ 30% during a combination of El Niño period and inactive phase of the MJO. Several other such cases have been assessed for different island nations, providing information that have potentially important implications for planning and preparing for TC risks in vulnerable Pacific Island nations.

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

Journal of Climate ◽

10.1175/2011jcli3511.1 ◽

2011 ◽

Vol 24 (7) ◽

pp. 1913-1921 ◽

Cited By ~ 33

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.

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