scholarly journals Numerical Investigation of a Flash Flood Process that Occurred in Zhongdu River, Sichuan, China

2021 ◽  
Vol 9 ◽  
Author(s):  
Qingyuan Yang ◽  
Tonghuan Liu ◽  
Jingjing Zhai ◽  
Xiekang Wang
Keyword(s):  
Sediment Transport ◽  
Water Level ◽  
Flash Flood ◽  
Peak Level ◽  
Field Studies ◽  
Bed Deformation ◽  
Bed Erosion ◽  
Set Up ◽  
Discharge Profile ◽  
The Impact

In 2018, a flash flood occurred in the Zhongdu river, which lies in Yibin, Sichuan province of China. The flood caused many casualties and significant damage to people living nearby. Due to the difficulty in predicting where and when flash floods will happen, it is nearly impossible to set up monitors in advance to detect the floods in detail. Field investigations are usually carried out to study the flood propagation and disaster-causing mechanism after the flood’s happening. The field studies take the relic left by the flash flood to deduce the peak level, peak discharge, bed erosion, etc. and further revel the mechanism between water and sediment transport during the flash flood This kind of relic-based study will generate bigger errors in regions with great bed deformation. In this study, we come up with numerical simulations to investigate the flash flood that happened in the Zhongdu river. The simulations are based on two-dimensional shallow water models coupled with sediment transport and bed deformation models. Based on the real water level and discharge profile measured by a hydrometric station nearby, the numerical simulation reproduced the flash flood in the valley. The results show the flood coverage, water level variation, and velocity distribution during the flood. The simulation offers great help in studying the damage-causing process. Furthermore, simulations without considering sediment transport are also carried out to study the impact of bed erosion and sedimentation. The study proved that, without considering bed deformation, the flood may be greatly underestimated, and the sediment lying in the valley has great impact on flood power.

scholarly journals Multi-scale hydrometeorological observation and modelling for flash-flood understanding

2014 ◽  
Vol 11 (2) ◽  
pp. 1871-1945 ◽  
Author(s):  
I. Braud ◽  
P.-A. Ayral ◽  
C. Bouvier ◽  
F. Branger ◽  
G. Delrieu ◽  
...  
Keyword(s):  
Hydrological Cycle ◽  
Flash Flood ◽  
Spatial Scales ◽  
Regional Scale ◽  
Runoff Generation ◽  
Catchment Scale ◽  
Ungauged Catchments ◽  
The Mediterranean ◽  
Set Up ◽  
The Impact

Abstract. This paper presents a coupled observation and modelling strategy aiming at improving the understanding of processes triggering flash floods. This strategy is illustrated for the Mediterranean area using two French catchments (Gard and Ardèche) larger than 2000 km2. The approach is based on the monitoring of nested spatial scales: (1) the hillslope scale, where processes influencing the runoff generation and its concentration can be tackled; (2) the small to medium catchment scale (1–100 km2) where the impact of the network structure and of the spatial variability of rainfall, landscape and initial soil moisture can be quantified; (3) the larger scale (100–1000 km2) where the river routing and flooding processes become important. These observations are part of the HyMeX (Hydrological Cycle in the Mediterranean Experiment) Enhanced Observation Period (EOP) and lasts four years (2012–2015). In terms of hydrological modelling the objective is to set up models at the regional scale, while addressing small and generally ungauged catchments, which is the scale of interest for flooding risk assessment. Top-down and bottom-up approaches are combined and the models are used as "hypothesis testing" tools by coupling model development with data analyses, in order to incrementally evaluate the validity of model hypotheses. The paper first presents the rationale behind the experimental set up and the instrumentation itself. Second, we discuss the associated modelling strategy. Results illustrate the potential of the approach in advancing our understanding of flash flood processes at various scales.

scholarly journals ASSESSING TIDAL FLOOD UPON SOLAR SALT FARMING AREA IN NORTH PART OF JAVA USING HYDRODYNAMIC MODEL

2019 ◽  
Vol XLII-3/W8 ◽  
pp. 283-286
Author(s):  
A. W. Nirwansyah ◽  
B. Braun
Keyword(s):  
Water Level ◽  
Extreme Event ◽  
Single Case ◽  
High Tide ◽  
Peak Level ◽  
Accurate Identification ◽  
Salt Production ◽  
North Part ◽  
Production Area ◽  
The Impact

<p><strong>Abstract.</strong> This study aims to assess the impact of high tide upon salt production areas in north part of Java, Indonesia. Single case in June 2016 was applied using MIKE 21 in salt production area of Cirebon. The inputs are tidal height records, bathymetry, digital elevation model (DEM) from Geospatial Information Agency (GIA), and wind data from OGIMET. Peak water level from tidal constituent is extracted from the simulation. The exposed that were generated from peak level of water elevation showed that tidal event has led to 82.9% of salt production area being inundated. West and east part are recorded as the most affected location due to this extreme event. The maximum water level has reached about 38 cm and covered more than 6,489.38 ha during the tide. Whilst the accurate identification will provide valuable information for flood assessment upon marginal agriculture in coastal area.</p>

scholarly journals Impact of Scientific Scrutiny after the 2016 Braunsbach Flash Flood on Flood-Risk Management in the State of Baden-Württemberg, Germany

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1165 ◽  
Author(s):  
Antje Witting ◽  
Frederik Brandenstein ◽  
Christiane Zarfl ◽  
Ana Lucía
Keyword(s):  
Risk Management ◽  
Sediment Transport ◽  
Flood Risk ◽  
Extreme Event ◽  
Flash Flood ◽  
Morphological Changes ◽  
Group Discussion ◽  
Flood Risk Management ◽  
Informal Assessment ◽  
The Impact

This paper presents interdisciplinary research focusing on the municipality of Braunsbach in the German state of Baden-Württemberg, where, in May 2016, a flash flood attracted media attention and scientific scrutiny that highlighted the fact that certain aspects of flood risk were overlooked during earlier assessments conducted by the municipality, such as sediment transport. Using a network analysis and a focus-group discussion, we traced the flow of knowledge through the reported interactions between governmental, private, and academic actors in the two and a half years after the event. From our analysis, we learned that the extreme event attracted scientists to the formal and informal assessment of the hazard and the associated damages. Most importantly, we found conditions under which scientific scrutiny is not detached from but becomes integrated in a governance setting. While it is through this process that sediment transport has become an integral part of flood-risk management in Baden-Württemberg, with an evident impact on the measures already implemented, the impact of morphological changes, as well as large wood and sediment transport, have not been factored into the risk assessment as of yet. These variations in scientific impact on the assessment can be explained by decision biases that can occur when decision makers are under pressure to tackle vulnerabilities and thus lack the time to deliberate in a way that uses all the available evidence.

scholarly journals Multi-scale hydrometeorological observation and modelling for flash flood understanding

2014 ◽  
Vol 18 (9) ◽  
pp. 3733-3761 ◽  
Author(s):  
I. Braud ◽  
P.-A. Ayral ◽  
C. Bouvier ◽  
F. Branger ◽  
G. Delrieu ◽  
...  
Keyword(s):  
Hydrological Cycle ◽  
Flash Flood ◽  
Spatial Scales ◽  
Regional Scale ◽  
Runoff Generation ◽  
Catchment Scale ◽  
Ungauged Catchments ◽  
The Mediterranean ◽  
Set Up ◽  
The Impact

Abstract. This paper presents a coupled observation and modelling strategy aiming at improving the understanding of processes triggering flash floods. This strategy is illustrated for the Mediterranean area using two French catchments (Gard and Ardèche) larger than 2000 km2. The approach is based on the monitoring of nested spatial scales: (1) the hillslope scale, where processes influencing the runoff generation and its concentration can be tackled; (2) the small to medium catchment scale (1–100 km2), where the impact of the network structure and of the spatial variability of rainfall, landscape and initial soil moisture can be quantified; (3) the larger scale (100–1000 km2), where the river routing and flooding processes become important. These observations are part of the HyMeX (HYdrological cycle in the Mediterranean EXperiment) enhanced observation period (EOP), which will last 4 years (2012–2015). In terms of hydrological modelling, the objective is to set up regional-scale models, while addressing small and generally ungauged catchments, which represent the scale of interest for flood risk assessment. Top-down and bottom-up approaches are combined and the models are used as "hypothesis testing" tools by coupling model development with data analyses in order to incrementally evaluate the validity of model hypotheses. The paper first presents the rationale behind the experimental set-up and the instrumentation itself. Second, we discuss the associated modelling strategy. Results illustrate the potential of the approach in advancing our understanding of flash flood processes on various scales.

scholarly journals LABORATORY EXPERIMENT ON CROSS-SHORE BARRIER SPIT EVOLUTION BY STORM DYNAMICS

2011 ◽  
Vol 1 (32) ◽  
pp. 32
Author(s):  
Nguyen Xuan Tinh ◽  
Magnus Larson ◽  
Chantal Donnelly ◽  
Hitoshi Tanaka
Keyword(s):  
Sediment Transport ◽  
Laboratory Experiment ◽  
Water Level ◽  
Barrier Island ◽  
Order Of Magnitude ◽  
Storm Dynamics ◽  
Mean Water Level ◽  
The Impact ◽  
Further Development ◽  
High Possibility

Every year there are many severe storms occurring around the world, in general, and in Japan, in particular. The occurrence of storms is expected to increase because of the global warming effects. An increasing wave height together with a rising mean water level during a storm create a high possibility for waves to overtop the beach crest causing a lot of sediment to be eroded to offshore areas or deposited in the inland direction. The study of the barrier island response to storms has therefore become very important in terms of sediment transport and beach morphology change, as well as damage to nearshore structures due to runup overwash and inundation overwash. However, changes in the beach profile and prevailing sediment transport mechanisms during a real event are difficult to obtain. Thus, laboratory studies are necessary to conduct. This study presents a laboratory experiment on the impact of storms on a sandy barrier islands. The main aim is to investigate the entire barrier island (or sand spit) response due to storm conditions considering the increase in water level due to storm surge. Also, further development of an analytical model for barrier profile change caused by runup overwash is presented and obtained results overall captured order-of-magnitude barrier face retreat and volume changes after the storm.

Characterizing Dam Induced Flood at Downstream of a Hydel Project 

2021 ◽  
Author(s):  
Dipsikha Devi ◽  
Anupal Baruah ◽  
Arup Kumar Sarma
Keyword(s):  
Water Level ◽  
Short Duration ◽  
Flash Flood ◽  
Daily Basis ◽  
Low Flow ◽  
Mitigation Measures ◽  
Hydropower Project ◽  
River Bank ◽  
Operating Policy ◽  
The Impact

&lt;p&gt;Flooding due to sudden release from a hydropower dam during monsoon is becoming a serious concern for downstream locality, especially when there is lack of coordination between the dam authority and the Disaster Management Authority (DMA) at downstream. For hilly river, a disastrous flash flood is generally caused by short duration high intensity precipitation and a pondage hydropower project cannot attenuate such flood. Generally, reservoir simulation/optimization for a hydropower project is carried out on monthly, ten-daily or at best on daily basis to determine the best operating policy and to analyze impact of such operation on the flow scenario and therefore, in conventional analysis such flash flood event goes un-noticed. A detailed investigation of the downstream flooding is required before the construction of any hydropower project with at least on hourly basis to get insight into the impact of such inflow at downstream. Non-availability of short duration precipitation/flow data in interior project area, particularly in developing country hinder such analysis. Need and scope of such analysis is demonstrated by using a typical flow hydrograph of 48 hours, having two flood peaks, as inflow to the Lower Subansiri Hydroelectric Project (LSHP). The project is located in the Subansiri River, the largest tributary of the Brahmaputra River in India. Two operating policies; i) Standard Operating Policy (SOP) and ii) Dynamic Programming (DP) generated operating policy have been tested and both the polices have generated similar hourly flow time series of total reservoir outflow (spill + Release). These reservoir operation models have been coupled with the hydrodynamic model to route the hourly reservoir outflow from LSHP to a flood prone area located 13Km downstream of it. Post dam flood scenario thus generated is compared with the pre dam flood scenario by routing the same inflow hydrograph without considering the dam. As the river has an embankment, and flooding occurs only when the embankment fails, a specified water level at the downstream section has been considered as critical for flooding for the purpose of a comparative study. &amp;#160;For the considered inflow hydrograph, it is observed that the flood magnitude is not increased by the action of dam operation rather peaks get slightly attenuated. However, in natural condition without dam, flood rises gradually providing prior information to the locality and providing sufficient time for completing pre-disaster actions based on experience. With inclusion of dam, peak flow rises vary rapidly from a very low flow without showing any indication of flood beforehand and thus flood becomes more disastrous. Sudden fluctuation of water level can also cause failure of river bank and progressive bank failure can eventually cause the embankment to fail. The analysis has shown the possible impact of hydel project with more clarity to help disaster manager prepare mitigation measures in an informed way.&lt;/p&gt;

Hydrodynamic Simulation of WeiYi Bridge in LiuZhou City, Guangxi Province, China

2011 ◽  
Vol 347-353 ◽  
pp. 1874-1877
Author(s):  
He Wei ◽  
Long Hua Gao ◽  
He Qin Chen ◽  
Jiu Fa Li
Keyword(s):  
Water Level ◽  
Hydrodynamic Model ◽  
River Flow ◽  
Guangxi Province ◽  
Hydrodynamic Simulation ◽  
Water Project ◽  
Adi Method ◽  
Model Control ◽  
Set Up ◽  
The Impact

Abstract. Liuzhou is an important city of flood protection in china.Flood protection assessment for any new relational-water project is prerequisite.In order to understand the impact to river flow,a 2-D hydrodynamic model is set up,and use ADI method to solute partial differential groups.The results can be shown as fellows: Computation is fast steady and convergent by ADI method,and associated errors of model control is satisfied.The bridge pier has major impacts on river flow.Velocity change due to bridge built could lead to riverbed erosion between piers,and siltation along the upstream and downstream of the Weiyi bridge.Water level could be rised in the bridge upstream with the raised water level of about 0.08m,which might affect drained floods to a some degree.

scholarly journals Siltation characteristics of the tail reach of Ganjiang River under the regulation of estuary gates

2020 ◽  
Vol 20 (8) ◽  
pp. 3707-3714
Author(s):  
Zhi-chao Wang ◽  
Xin-fa Xu ◽  
Zhi-wen Huang ◽  
Nian-hua Wu ◽  
Su-fen Zhou
Keyword(s):  
Sediment Transport ◽  
Water Level ◽  
Physical Model ◽  
Suspended Sediment ◽  
Development Trend ◽  
Jiangxi Province ◽  
Topographic Features ◽  
Deposition Area ◽  
Set Up ◽  
Deposition Test

Abstract To alleviate the problem that the water level drops more and more seriously in recent years, Jiangxi province proposes to set up regulation gates at each of the estuaries of Ganjiang River to raise the water level in Nanchang city during the dry season. The operation of this project will raise the upstream water level, which means the sediment transport rate will decrease and lead to deposition problems. In order to find out the deposition area and development trend, we carried out the suspended sediment deposition test on an existing physical model. The study shows that the upstream sediment is mainly deposited in the reaches near the two deltas. Some special topographic features are more likely to cause siltation, such as the wide and deep thalweg and the backflow areas at the downstream of convex banks. After the operation of the project, the erosion trend of the upper reaches of the central and southern branches will change to siltation, and the siltation of the upper reaches of the Western branch will be further strengthened. Fifteen years later, with the decrease of the upstream sediment intensity, the sediment siltation phenomenon will gradually move downstream, however, this will be a long process.

scholarly journals Mass Mortality of Invasive Snails: Impact of Nutrient Release on Littoral Water Quality

Diversity ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 362
Author(s):  
Liubov Yanygina
Keyword(s):  
Water Quality ◽  
Water Level ◽  
Total Phosphorus ◽  
Anthropogenic Impacts ◽  
Nutrient Release ◽  
Field Studies ◽  
Mass Mortality ◽  
Novosibirsk Reservoir ◽  
The Impact ◽  
Water Level Regulation

Mollusks are the macroinvertebrates most commonly introduced into fresh water. In invaded reservoirs, alien mollusks form a large biomass due to their large size. Climate change, water level regulation, and anthropogenic impacts on the environment lead to the drying up of water bodies and the death of littoral macroinvertebrates. To assess the impact of invasive snail mass mortality on water quality, laboratory experiments on the snail tissue decomposition were performed, the potential release of nutrients into aquatic ecosystems was calculated, and the predicted concentrations of nutrients were verified by field studies. The laboratory experiment showed quick decomposition of the common river snail Viviparus viviparus tissues with release into the environment of ammonium and total phosphorus of 2.72 ± 0.14 mg and 0.10 ± 0.02 mg, respectively, per gram of decomposing tissue. The concentrations of ammonium, nitrates, and total phosphorus at the site of snail death reached 2.70 ± 0.10, 3.13 ± 0.38 and 0.30 ± 0.02 mg/L, respectively. This indicates local contamination of the Novosibirsk reservoir littoral with decomposition products. The aquatic management, water level regulation, and control of undesirable species should take into account the likelihood of water quality decreasing as a result of macroinvertebrate mass mortality.

MOTIF DAN DAMPAK PERNIKAHAN DINI DI INDARUNG NGALAU BATU GADANG

2018 ◽  
Vol 1 (1) ◽  
pp. 1
Author(s):  
Murisal Murisal
Keyword(s):  
Young Men ◽  
Early Marriage ◽  
Marriage Law ◽  
Men And Women ◽  
Home Life ◽  
Family Household ◽  
Set Up ◽  
The Impact ◽  
Husband And Wife

Motif and Impact of Early Marriage in Indarung Ngalau Batu Gadang.Penelitian is motivated by teenagers who married early on. Today, young men and women have a tendency to be less prepared to enter the home life, they are only ready to marry (ready here can be interpreted, maturity in terms of financial, understand what the meaning of marriage according to marriage law) is the bond of inner birth between a man and a woman as husband and wife for the purpose of forming a happy and eternal family (household) based on the Supreme Godhead while they are not ready to set up a home, whereas to build a household requires preparation both physically and spiritually . The purpose of this study to determine the motives underlying adolescents to make early marriage and the impact caused in the household as a result of the marriage.

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