scholarly journals Quantifying the contribution of flood intensity indicators with the projection pursuit model

2017 ◽  
Vol 49 (1) ◽  
pp. 60-71 ◽  
Author(s):  
Lina Wang ◽  
Yanqing Lian ◽  
Xiaohong Chen
Keyword(s):  
Southern China ◽  
Projection Pursuit ◽  
Flood Events ◽  
Flood Duration ◽  
Flood Discharge ◽  
Wujiang River ◽  
Flood Volume ◽  
Projection Pursuit Model ◽  
Flood Intensity ◽  
Peak Flood

Abstract Identifying the various factors that affect the intensity of a flood event, such as its duration and volume, is essential for strategic planning and flood management. Further, quantifying the impacts of these major factors on flood intensity using the contribution rate is essential, but technically challenging. In this study, the authors have adopted the projection pursuit model to quantify the contribution rates of peak flood stage and peak flood discharge, flood duration, and total flood volume (the maximum 12-, 24-, and 72-hour flood volumes) in the Wujiang River in Southern China. This study showed that peak flood discharge and total flood volume were the two dominant factors impacting flood intensity. Although flood duration can be a major factor for some flood events, it contributed the least to flood intensity for most of the historic flood events studied. Likewise, the maximum 24-hour and 72-hour flood volumes contributed little to flood intensity. Findings from this study not only demonstrated the successful adoption of the projection pursuit model for contribution rates, but also provided critical information for planning and managing the regional hydraulic resources in the Wujiang River.

scholarly journals A sub-centennial-scale optically stimulated luminescence chronostratigraphy and late Holocene flood history from a temperate river confluence

Geology ◽  
2020 ◽  
Vol 48 (8) ◽  
pp. 819-825 ◽  
Author(s):  
Ben Pears ◽  
Antony G. Brown ◽  
Phillip S. Toms ◽  
Jamie Wood ◽  
David Sanderson ◽  
...  
Keyword(s):  
Land Use ◽  
Accumulation Rate ◽  
Optically Stimulated Luminescence ◽  
Ice Age ◽  
Flood Events ◽  
14C Dating ◽  
Flood Duration ◽  
Flood Magnitude ◽  
High Flood ◽  
Flood Intensity

Abstract River confluences can be metastable and contain valuable geological records of catchment response to decadal- to millennial-scale environmental change. However, in alluvial reaches, flood stratigraphies are particularly hard to date using 14C. In this paper, we use a novel combination of optically stimulated luminescence and multiproxy sedimentological analyses to provide a flood record for the confluence of the Rivers Severn and Teme (United Kingdom) over the past two millennia, which we compare with independent European climate records. The results show that by ca. 2000 yr B.P., the Severn-Teme confluence had stabilized and overbank alluviation had commenced. Initially, this occurred from moderately high flood magnitudes between ca. 2000 and 1800 yr B.P. (50 BCE–150 CE), but was followed from 1800 to 1600 yr B.P. (150–350 CE) by fine alluvial deposition and decreased flood intensity. From 1600 to 1400 yr B.P. (350–550 CE), the accumulation rate increased, with evidence of large flood events associated with the climatic deterioration of the Dark Age Cold Period. Following a period of reduced flood activity after ca. 1400 yr B.P. (ca. 550 CE), larger flood events and increase in accumulation rate once again became more prevalent from ca. 850 yr B.P. (ca. 1100 CE), coincident with the start of the Medieval Climate Anomaly, a period associated with warmer, wetter conditions and increased land-use intensity. This state persisted until ca. 450 yr B.P. (ca. 1500 CE), after which increased flood magnitudes can be associated with climatic variations during the Little Ice Age. We demonstrate that from the combination of high-resolution dating techniques and multiple analytical parameters, distinctive phases of relative flood magnitude versus flood duration can be determined to a detailed chronological precision beyond that possible from 14C dating. This permits the identification of the regional factors behind floodplain sedimentation, which we correlate with the intensification of land-use and climatic drivers over the last two millennia.

Contextualized sedimentation rates for large floods along the lower Mississippi River: the importance of flood duration

2021 ◽  
Author(s):  
Paul Hudson ◽  
Franklin Heitmuller ◽  
Samuel Muñoz ◽  
Jansen Costello
Keyword(s):  
Suspended Sediment ◽  
Sedimentation Rate ◽  
Field Data ◽  
Flood Events ◽  
Sediment Thickness ◽  
Flood Duration ◽  
Sedimentary Deposits ◽  
Sand Sheet ◽  
Overbank Sedimentation ◽  
Sampling Procedures

<p>Flood sedimentary deposits vary due to upper basin and lower basin controls. In this study we focus on overbank sediment thickness, which over longer periods drives changes to riparian aquatic habitat and floodplain construction. The study setting is a ~25 km long segment of the lower Mississippi alluvial valley, between Natchez, MS and Red River Landing, LA. We report new field data for overbank sedimentation generated by compound flooding over 2018 and 2019 hydrologic years, and compare with sedimentation data from prior large flood events. Overbank conditions in 2018 and 2019 persisted for 286 days (at Natchez, MS). During the 2019 hydrologic year the Mississippi was overbank for a record duration of 216 days, resulting in a much greater duration of overbank sedimentation than the 2011 (53 days) and 1973 (90 days) flood events.</p><p>The thickness of overbank deposits are reported for 48 field sites across a range of depositional environments typical of large lowland meandering river floodplains. Flood deposits were sampled in October 2019 using conventional field sampling procedures, including sedimentation traps (artificial grass mats installed in October 2017) and recognition of recent sediment deposited atop buried organic layers. The thickness of each reported sample is an average of three measurements obtained at each field site.</p><p>The average thickness of flood deposit samples over 2018-2019 hydrologic years is 71 mm, with variability according to distance from channel and floodplain depositional environment. Maximum sedimentation was associated with crevasse (750 mm) and sand sheet (1,430 mm) deposition along the crest of natural levees. Sedimentation thickness decreases within ~250 m of the channel, but remains high at a distance of ~3.5 km (30 mm). Beyond the range of sand sheet deposition, overbank deposition is likely influenced by variability in floodplain hydrology and geomorphology across natural levee (181 mm), meander scroll (30 mm), old channel (77 mm), and backswamp (108 mm) environments. High backswamp sedimentation at the study site is likely influenced by historic hydraulic engineering for flood control, which has altered local sedimentation patterns.</p><p>The 2018-2019 sedimentation data are contextualized by comparison with field data from the record 2011 magnitude flood (peak Q of 65,978 m<sup>3</sup>/s at Vicksburg, MS, USGS 0728900) and the historic 1973 flood (55,558 m<sup>3</sup>/s).  Average sediment thickness for the 2011 and 1973 overbank deposits was 42 mm (n=49) and 230 mm (n=31), respectively. The 2018-2019 daily sedimentation rate (0.25 mm/day) is much less than 2011 (0.75 mm/day). Thus, the much thicker sedimentary deposits for the 2018-2019 events suggests the greater importance of flood duration – rather than flood magnitude – to overall floodplain processes and alluvial fill chronologies along lowland rivers. The much lower flood sedimentation rate for 2018-2019 in comparison with 1973 (2.49 mm/day) may reveal the persistent decline in Mississippi suspended sediment loads since the early 1950s. Study results are further contextualized by considering corresponding event-based discharge – suspended sediment dynamics, sediment province, as well as flood hydroclimatology.</p>

Water Quality Assessment on Fujiang River of China Using Projection Pursuit Model

2011 ◽  
Vol 204-210 ◽  
pp. 1326-1329
Author(s):  
Ben Lin Dai ◽  
Yu Long He ◽  
Jin Rong ◽  
Xiao Hui Jiang
Keyword(s):  
Water Quality ◽  
Quality Assessment ◽  
Projection Pursuit ◽  
Water Quality Assessment ◽  
Comparison Results ◽  
Volatile Phenol ◽  
Status Assessment ◽  
Water Quality Status ◽  
Projection Pursuit Model ◽  
Quality Status

Due to the increasingly serious water quality degradation on river, the study on river water quality status assessment has attracted more and more attention of the researchers and decision-makers. In this paper, water quality assessment of Fujiang River from January 2005 to December 2005 was studied by projection pursuit model (PPM). The water quality status of Fujiang River was assessed by the use of 10 monitoring sections, with DO, CODMn, BOD5, NH3-N, Petroleum, and Volatile phenol indicators. Based on the PPM analysis procedures, the assessed sections are described into 1 “category 1”, 4 “category 2” and 5 “category 3” states in 2005. The relative comparison results show that water quality status spatial order of Fujiang River from bad to good is: Fj09<Fj02< Fj10<Fj07< Fj03<Fj05<Fj04< Fj06<Fj08<Fj01.

scholarly journals Spatiotemporal variation in global floods with different affected areas and the contribution of influencing factors to flood-induced mortality (1985–2019)

2022 ◽  
Author(s):  
Tian Liu ◽  
Peijun Shi ◽  
Jian Fang
Keyword(s):  
Influencing Factors ◽  
Large Scale ◽  
Human Life ◽  
Flood Frequency ◽  
Spatiotemporal Variation ◽  
Mountainous Area ◽  
Flood Events ◽  
Protection Measures ◽  
Flood Duration ◽  
Level Ii

AbstractFloods are great threats to human life and property. Extensive research has investigated the spatiotemporal variation in flood occurrence, while few have studied the heterogeneity in global flood events of different sizes, which may require different coping strategies and risk reduction policies. In this study, we analysed the spatiotemporal patterns of global flood events with different affected areas (classified in three levels) during 1985–2019 and examined the contribution of different influencing factors to flood-induced mortality using Geodetector. The results show that (1) the increase in global flood frequency was mainly caused by Level II and Level III floods, and the average area affected by flood events has been increasing yearly since 1985. (2) In America and Africa, the frequency of Level III floods has increased monotonically. At the same time, the frequency of Level I floods in Europe and Level II floods in Asia has increased significantly. (3) For Europe and Asia, most of the deaths occurred with Level II floods; while for America and Africa, Level III floods caused the most mortality. (4) The top three factors contributing to the spatial heterogeneity in flood-induced mortality were the affected population, GDP per capita and flood duration. The contribution of each factor varied among the different types of floods. Topographic factors (percentage of mountainous area) magnified flood-induced mortality during extreme events with heavy rainfall, especially for Level III floods. The heterogeneity in flood frequency and flood-induced mortality indicates that flood protection measures should be more targeted. In addition, the increase in large-scale floods (Level III) highlights the need for transregional cooperation in flood risk management.

Peak Flood Discharge Confidence Limits

1969 ◽  
Vol 95 (1) ◽  
pp. 161-174
Author(s):  
Richard M. Shane ◽  
Walter R. Lynn
Keyword(s):  
Confidence Limits ◽  
Flood Discharge ◽  
Peak Flood

scholarly journals Identify and Assess Hydropower Project’s Multidimensional Social Impacts with Rough Set and Projection Pursuit Model

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Hui An ◽  
Wenjing Yang ◽  
Jin Huang ◽  
Ai Huang ◽  
Zhongchi Wan ◽  
...  
Keyword(s):  
Rough Set ◽  
Index System ◽  
Social Impact ◽  
Projection Pursuit ◽  
Cultural Development ◽  
Evaluation Index System ◽  
Assessment Model ◽  
Evaluation Index ◽  
The Social ◽  
Projection Pursuit Model

To realize the coordinated and sustainable development of hydropower projects and regional society, comprehensively evaluating hydropower projects’ influence is critical. Usually, hydropower project development has an impact on environmental geology and social and regional cultural development. Based on comprehensive consideration of complicated geological conditions, fragile ecological environment, resettlement of reservoir area, and other factors of future hydropower development in each country, we have constructed a comprehensive evaluation index system of hydropower projects, including 4 first-level indicators of social economy, environment, safety, and fairness, which contain 26 second-level indicators. To solve the problem that existing models cannot evaluate dynamic nonlinear optimization, a projection pursuit model is constructed by using rough set reduction theory to simplify the index. Then, an accelerated genetic algorithm based on real number coding is used to solve the model and empirical study is carried out with the Y hydropower station as a sample. The evaluation results show that the evaluation index system and assessment model constructed in our paper effectively reduce the subjectivity of index weight. Applying our model to the social impact assessment (SIA) of related international hydropower projects can not only comprehensively analyze the social impact of hydropower projects but also identify important social influencing factors and effectively analyze the social impact level of each dimension. Furthermore, SIA assessment can be conducive to project decision-making, avoiding social risks and social stability.

scholarly journals Geospatial Modelling of Watershed Peak Flood Discharge in Selangor, Malaysia

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2490 ◽  
Author(s):  
Ryan Cheah ◽  
Lawal Billa ◽  
Andy Chan ◽  
Fang Yenn Teo ◽  
Biswajeet Pradhan ◽  
...  
Keyword(s):  
Hydrological Modeling ◽  
Estimation Methods ◽  
Coefficient Of Determination ◽  
Storm Event ◽  
Storm Events ◽  
Unit Hydrograph ◽  
Runoff Simulation ◽  
Flood Discharge ◽  
Geospatial Modelling ◽  
Peak Flood

Conservative peak flood discharge estimation methods such as the rational method do not take into account the soil infiltration of the precipitation, thus leading to inaccurate estimations of peak discharges during storm events. The accuracy of estimated peak flood discharge is crucial in designing a drainage system that has the capacity to channel runoffs during a storm event, especially cloudbursts and in the analysis of flood prevention and mitigation. The aim of this study was to model the peak flood discharges of each sub-watershed in Selangor using a geographic information system (GIS). The geospatial modelling integrated the watershed terrain model, the developed Soil Conservation Service Curve Cumber (SCS-CN) and precipitation to develop an equation for estimation of peak flood discharge. Hydrological Engineering Center-Hydrological Modeling System (HEC-HMS) was used again to simulate the rainfall-runoff based on the Clark-unit hydrograph to validate the modelled estimation of peak flood discharge. The estimated peak flood discharge showed a coefficient of determination, r2 of 0.9445, when compared with the runoff simulation of the Clark-unit hydrograph. Both the results of the geospatial modelling and the developed equation suggest that the peak flood discharge of a sub-watershed during a storm event has a positive relationship with the watershed area, precipitation and Curve Number (CN), which takes into account the soil bulk density and land-use of the studied area, Selangor in Malaysia. The findings of the study present a comparable and holistic approach to the estimation of peak flood discharge in a watershed which can be in the absence of a hydrodynamic simulation model.

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