scholarly journals Coastal flood risk within a peri-urban area: SUSSEX Inlet district, SE Australia

2021 ◽  
Author(s):  
E. F. Asbridge ◽  
D. Low Choy ◽  
B. Mackey ◽  
S. Serrao-Neumann ◽  
P. Taygfeld ◽  
...  
Keyword(s):  
Flood Risk ◽  
Flood Hazard ◽  
Extreme Rainfall ◽  
Cost Effective ◽  
Extreme Rainfall Events ◽  
Hazard Exposure ◽  
Rate Of Increase ◽  
Eastern Australia ◽  
Planning Strategies ◽  
Natural Resource Managers

AbstractThe peri-urban interface (PUI) exhibits characteristic qualities of both urban and rural regions, and this complexity has meant that risk assessments and long-term planning for PUI are lagging, despite these areas representing new developing settlement frontiers. This study aims to address this knowledge gap by modifying an existing approach to quantify and assess flood risk. The risk triangle framework was used to map exposure, vulnerability and biophysical variables; however, in a novel application, the risk triangle framework was adapted by presuming that there is a variation in the degree of exposure, vulnerability and biophysical variables. Within Australia and globally, PUIs are often coastal, and flood risk associated with rainfall and coastal inundation poses considerable risk to communities in the PUI; these risks will be further exacerbated should projections of increasing frequency of extreme rainfall events and accelerating sea-level rise eventuate. An indicator-based approach using the risk triangle framework that maps flood hazard, exposure and vulnerability was used to integrate the biophysical and socio-economic flooding risk for communities in PUI of the St Georges Basin and Sussex Inlet catchments of south-eastern Australia. Integrating the flood risk triangle with future scenarios of demographic and climate change, and considering factors that contribute to PUI flood risk, facilitated the identification of planning strategies that would reduce the future rate of increase in flood risk. These planning strategies are useful for natural resource managers and land use planners across Australia and globally, who are tasked with balancing socio-economic prosperity for a changing population, whilst maintaining and enhancing ecosystem services and values. The indicator-based approach used in this study provides a cost-effective first-pass risk assessment and is a valuable tool for decision makers planning for flood risk across PUIs in NSW and globally.

scholarly journals Large scale and sub-regional connections in the lead up to summer heat wave and extreme rainfall events in eastern Australia

2014 ◽  
Vol 44 (7-8) ◽  
pp. 1823-1840 ◽  
Author(s):  
Ghyslaine Boschat ◽  
Alexandre Pezza ◽  
Ian Simmonds ◽  
Sarah Perkins ◽  
Tim Cowan ◽  
...  
Keyword(s):  
Heat Wave ◽  
Large Scale ◽  
Extreme Rainfall ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Summer Heat ◽  
Eastern Australia

scholarly journals Bayesian objective classification of extreme UK daily rainfall for flood risk applications

2008 ◽  
Vol 5 (6) ◽  
pp. 3033-3060 ◽  
Author(s):  
M. A. Little ◽  
H. J. E. Rodda ◽  
P. E. McSharry
Keyword(s):  
Flood Risk ◽  
Clustering Algorithm ◽  
Daily Rainfall ◽  
Extreme Rainfall ◽  
Spatial Layout ◽  
Past Century ◽  
Extreme Rainfall Events ◽  
Typing Scheme ◽  
Objective Classification ◽  
Flood Simulations

Abstract. In this study we describe an objective classification scheme for extreme UK daily precipitation to be used in flood risk analysis applications. We create a simplified representation of the spatial layout of extreme events based on a new digital archive of UK rainfall. This simplification allows a Bayesian clustering algorithm to compress these representations down to eight prototypical patterns of extreme falls. These patterns are then verified against a five-class, manual, subjective typing scheme, produced independently using known meteorological mechanisms, isohyetal maps and additional descriptive text from the archive. Compared against the manual scheme, the new objective scheme can reproduce the known meteorological conditions, both in terms of spatial layout and seasonal timing, and is shown to be of hydrological relevance when matched to several notable flooding events in the past century. Furthermore, it is computationally simple and straightforward to apply in classifying future extreme rainfall events. We discuss the practical use of this new typing scheme in flood simulations and climate change applications.

scholarly journals Assessing Redundancy in Stormwater Structures Under Hydraulic Design

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1003 ◽  
Author(s):  
Sina Hesarkazzazi ◽  
Mohsen Hajibabaei ◽  
Julian David Reyes-Silva ◽  
Peter Krebs ◽  
Robert Sitzenfrei
Keyword(s):  
Complex Network ◽  
Flow Direction ◽  
Water Discharge ◽  
Extreme Rainfall ◽  
Cost Effective ◽  
Negative Effects ◽  
Flow Paths ◽  
Extreme Rainfall Events ◽  
Extreme Precipitation Events ◽  
Hydraulic Design

As environmental change is happening at an unprecedented pace, a reliable and proper urban drainage design is required to alleviate the negative effects of unexpected extreme rainfall events occurring due to the natural and anthropogenic variations such as climate change and urbanization. Since structure/configuration of a stormwater network plays an imperative role in the design and hydraulic behavior of the system, the goal of this paper is to elaborate upon the significance of possessing redundancy (e.g., alternative flow paths as in loops) under simultaneous hydraulic design in stormwater pipe networks. In this work, an innovative approach based on complex network properties is introduced to systematically and successively reduce the number of loops and, therefore, the level of redundancy, from a given grid-like (street) network. A methodology based on hydrodynamic modelling is utilized to find the optimal design costs for all created structures while satisfying a number of hydraulic design constraints. As a general implication, when structures are subject to extreme precipitation events, the overall capability of looped configurations for discharging runoff more efficiently is higher compared to more branched ones. The reason is due to prevailing (additional) storage volume in the system and existing more alternative water flow paths in looped structures, as opposed to the branched ones in which only unique pathways for discharging peak runoff exist. However, the question arises where to best introduce extra paths in the network? By systematically addressing this question with complex network analysis, the influence of downstream loops was identified to be more significant than that of upstream loops. Findings, additionally, indicated that possessing loop and introducing extra capacity without determining appropriate additional pipes positions in the system (flow direction) can even exacerbate the efficiency of water discharge. Considering a reasonable and cost-effective budget, it would, therefore, be worthwhile to install loop-tree-integrated stormwater collection systems with additional pipes at specific locations, especially downstream, to boost the hydraulic reliability and minimize the damage imposed by the surface flooding upon the metropolitan area.

scholarly journals One-Dimensional (1D) River Analysis of a River Basin in Southern Luzon Island in the Philippines Using Lidar Digital Elevation Model

2018 ◽  
Vol 7 (3.7) ◽  
pp. 29
Author(s):  
Fibor J. Tan ◽  
Edgardo Jade R. Rarugal ◽  
Francis Aldrine A. Uy
Keyword(s):  
Digital Elevation Model ◽  
Flood Hazard ◽  
Monsoon Season ◽  
Extreme Rainfall ◽  
The Philippines ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
One Dimensional ◽  
Digital Elevation ◽  
Elevation Model

Flooding is a perennial problem in the Philippines during the monsoon season intensified by the effects of typhoon. On average, there are 20 typhoons that enter the Philippine Area of Responsibility (PAR), and many of these make landfall causing catastrophic aftermath. Extreme rainfall events could lead to flooding in the downstream floodplain and landslide in mountainous terrains. In this study, which is for the case of Calumpang River that drains to the populated and developing region of Batangas City, the focus is on flooding in the floodplain areas. The river was modelled using LiDAR digital elevation model (DEM) that has an accuracy of 20cm in the vertical and 50cm in the horizontal. The result of this is river hydraulic model that can be used to accurately generate flood inundation simulations and flood hazard maps.  

Variation of Uncertainty of Drainage Density in Flood Hazard Mapping Assessment with Coupled 1D-2D Hydrodynamics Model

2021 ◽  
Author(s):  
Song-Yue Yang ◽  
Che-Hao Chang ◽  
Chih-Tsung Hsu ◽  
Shiang-Jen Wu
Keyword(s):  
Return Period ◽  
Flood Hazard ◽  
Extreme Rainfall ◽  
Drainage Density ◽  
Hazard Mapping ◽  
Extreme Rainfall Events ◽  
Model Sets ◽  
Density Values ◽  
Rainfall Reduction ◽  
Flooded Area

Abstract Coupled 1D-2D hydrodynamic models are widely utilized in flood hazard mapping. Researchers have explored several uncertainties in flood hazard mapping, but have not addressed the uncertainty of drainage density. Drainage density is equal to total length of the drainage divided by the catchment area. The model sets denser the tributary drainages for higher drainage density values. This study uses a designed case and a real case, Yanshuixi Drainage in Tainan, Taiwan, to assess the uncertainty of drainage density in flood hazard mapping. Analytical results indicate that under the same return period rainfall, reduction in tributary drainages in a model (indicating a lower drainage density) results in an underestimate of the flooded area in tributary drainages. This underestimate causes higher peak discharges and total volume of discharges in the drainages, leading to flooding in certain downstream reaches, thereby overestimating the flooded area. The uncertainty of drainage density decreases with increased rainfall. We suggest that modeling flood hazard mapping with low return period rainfalls requires tributary drainages. For extreme rainfall events, a lower drainage density could be selected, but the drainage density of local key areas should be raised.

Flood risk management under climate change: a hydro-economic perspective

2018 ◽  
Vol 18 (5) ◽  
pp. 1832-1840 ◽  
Author(s):  
Rohini P. Devkota ◽  
Tek Maraseni
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Flood Hazard ◽  
Methodological Approach ◽  
Extreme Rainfall ◽  
Developed Countries ◽  
Flood Management ◽  
Policy Implications ◽  
Extreme Rainfall Events ◽  
Management Plans

Abstract Most developing countries, like Nepal, are expected to experience the greatest impact of climate change (CC) sooner and on a greater magnitude than other developed countries. Increase in the magnitude and frequency of extreme rainfall events is likely to increase the risk of flooding in rivers. The West Rapti River basin is one of the most flood prone and also one of the most dynamic and economically important basins of Nepal. This study elicits the willingness to pay (WTP) from the local people in the basin to reduce risks from possible floods due to CC. The WTP for flood mitigation in different flood hazard zones and flood scenarios were determined using referendum method and a face to face questionnaire survey. From a total of 720 households across all flood zones, a stratified randomly selected sample of 210 households was surveyed. The sample included households from a range of socio-economic backgrounds. The average WTP varied by flood hazard zone and within each zone, by CC-induced flood scenarios. The average WTP of respondents was highest for the critical flood prone zone, followed by moderate and low flood prone zones. Similarly, within each zone, the average WTP increased with increasing flood magnitudes due to CC. The variation of average WTP of respondents in different flood prone zones and scenarios indicate different levels of perceived severity. Moreover, the introduction of the concept of ‘man-day’ or ‘labour-day’ in WTP research is a novel and applicable methodological approach, particularly in the South Asian region. The findings of this study are useful for policy implications for the design of participatory flood management plans in the river basin.

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.

Structure Specific Flood Risk Based Insurance

2017 ◽  
Vol 04 (03) ◽  
pp. 1750011 ◽  
Author(s):  
Howard Kunreuther ◽  
John Dorman ◽  
Scott Edelman ◽  
Chris Jones ◽  
Marilyn Montgomery ◽  
...  
Keyword(s):  
North Carolina ◽  
Flood Risk ◽  
Flood Hazard ◽  
Cost Effective ◽  
Mitigation Measures ◽  
Loss Reduction ◽  
Hazard Maps ◽  
Single Family ◽  
Imaging Detection ◽  
Price Insurance

This paper highlights the importance of developing accurate flood hazard maps to price insurance effectively and to communicate flood risk to interested parties. Risk-based insurance premiums can encourage insurance purchase and investment in cost effective mitigation measures. We undertake a study using light imaging detection and ranging (LIDAR) technology and depth damage curves to determine risk-based rates for residential structures in three counties in the state of North Carolina. We then compare these prices with current premiums charged to homeowners by the National Flood Insurance Program (NFIP) for 11,915 single-family residences. NFIP premiums are significantly higher than risk-based premiums for over 90 percent of the homes in each of the counties in our study. Risk-based prices are higher than NFIP premiums only in instances where buildings are predicted to suffer damage from more frequent, shallow floods that are currently not considered explicitly in NFIP premium calculations. Accurate flood maps are needed to determine cost-effective loss reduction measures and to address issues of affordability and fairness for homeowners currently living in flood-prone areas.

 Geo-historical analysis of flood impacts in a large Alpine catchment (Arve River, French Alps, 1850 – 2015).

2021 ◽  
Author(s):  
Eva Boisson ◽  
Bruno Wilhelm ◽  
Emmanuel Garnier ◽  
Alain Mélo ◽  
Sandrine Anquetin ◽  
...  
Keyword(s):  
Flood Risk ◽  
Flood Hazard ◽  
Historical Analysis ◽  
European Alps ◽  
Source Effects ◽  
Ice Melt ◽  
Hazard Exposure ◽  
Flood Impacts ◽  
Main River ◽  
Alpine Catchments

<p>In France, flooding is the most common and damaging natural hazard. Due to global warming, it is expected to globally exacerbate, and it could be even more pronounced in the European Alps that warm at a rate twice as high in the Northern Hemisphere. The Alps are densely populated, increasing exposure and vulnerability to flood hazard. To approach long-term evolutions of past flood occurrence and related socio-economic impacts in relation to changes in the flood risk components (i.e. hazard, exposure and vulnerability), the study of historical records is highly relevant.</p><p>To this aim we build and analyze the newly constituted database of Historical Impacts of Floods in the Arve Valley (HIFAVa), located in French Northern Alps and starting in 1850. The database reports flood occurrences and impacts in a well-documented Alpine catchment that encompasses both a hydrological and societal diversity.</p><p>We analyze past impacts in regard to their characteristics and evolution in both time and space. Our results show an increasing occurrence of impacts from 1920 onwards, which is more likely related to indirect source effects and/or increasing exposure of goods and people rather than hydrological changes. The analysis reveals that small mountain streams and particularly glacial streams caused more impacts (67%) than the main river. While increase in heavy rainfall and ice melt are expected to enhance flood hazard in small Alpine catchments, this finding calls to pay a particular attention to flood risk assessment and management in small catchments.</p>

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