Analysis of Small and Medium–Scale River Flood Risk in Case of Exceeding Control Standard Floods Using Hydraulic Model

Exceeding control standard floods pose threats to the management of small and medium–scale rivers. Taking Fuzhouhe river as an example, this paper analyzes the submerged depth, submerged area and arrival time of river flood risk in the case of exceeding control standard floods (with return period of 20, 50, 100 and 200 years) through a coupled one– and two–dimensional hydrodynamic model, draws the flood risk maps and proposes emergency plans. The simulation results of the one–dimensional model reveal that the dikes would be at risk of overflowing for different frequencies of floods, with a higher level of risk on the left bank. The results of the coupled model demonstrate that under all scenarios, the inundation area gradually increases with time until the flood peak subsides, and the larger the flood peak, the faster the inundation area increases. The maximum submerged areas are 42.73 km2, 65.95 km2, 74.86 km2 and 82.71 km2 for four frequencies of flood, respectively. The change of submerged depth under different frequency floods shows a downward–upward–downward trend and the average submerged depth of each frequency floods is about 1.4 m. The flood risk maps of different flood frequencies are created by GIS to analyze flood arrival time, submerged area and submerged depth to plan escape routes and resettlement units. The migration distances are limited within 4 km, the average migration distance is about 2 km, the vehicle evacuation time is less than 20 min, and the walking evacuation time is set to about 70 min. It is concluded that the flood risk of small and medium–scale rivers is a dynamic change process, and dynamic flood assessment, flood warning and embankment modification scheme should be further explored.

Download Full-text

Flood Routing Process and High Dam Interception of Natural Discharge from the 2018 Baige Landslide-Dammed Lake

Water ◽

10.3390/w12020605 ◽

2020 ◽

Vol 12 (2) ◽

pp. 605 ◽

Cited By ~ 1

Author(s):

Bin-Rui Gan ◽

Xing-Guo Yang ◽

Hai-Mei Liao ◽

Jia-Wen Zhou

Keyword(s):

Flood Control ◽

Arrival Time ◽

Arch Dam ◽

Flood Routing ◽

Hydraulic Calculation ◽

Outburst Flood ◽

Jinsha River ◽

Flood Peak ◽

Inundation Area ◽

High Dams

The outburst flood of the Baige landslide dam caused tremendous damage to infrastructure, unfinished hydraulic buildings, roads, and bridges that were built or under construction along the Jinsha River. Can downstream hydraulic buildings, such as high dams with flood control and discharge function, accommodate outburst floods or generate more serious losses due to wave overtopping? In this study, the unsteady flow of a one-dimensional hydraulic calculation was used to simulate natural flood discharge. Assuming a high dam (Yebatan arch dam) is constructed downstream, the flood processes were carried out in two forms of high dam interception (complete interception, comprehensive flood control of blocking and draining). Moreover, three-dimensional visualization of the inundation area was performed. Simulation results indicate that the Yebatan Hydropower Station can completely eliminate the outburst flood risk even under the most dangerous situations. This station can reduce the flood peak and delay the peak flood arrival time. Specifically, the flood peak decreased more obviously when it was closer to the upstream area, and the flood peak arrival time was more delayed when the flood spread further downstream. In addition, the downstream water depth was reduced by approximately 10 m, and the inundation area was reduced to half of the natural discharge. This phenomenon shows that hydraulic buildings such as high dams can reduce the inundation area of downstream farmlands and extend the evacuation time for downstream residents during the flood process, thus reducing the loss of life and property.

Download Full-text

Towards risk-based flood management in highly productive paddy rice cultivation – concept development and application to the Mekong Delta

Natural Hazards and Earth System Science ◽

10.5194/nhess-18-2859-2018 ◽

2018 ◽

Vol 18 (11) ◽

pp. 2859-2876 ◽

Cited By ~ 4

Author(s):

Nguyen Van Khanh Triet ◽

Nguyen Viet Dung ◽

Bruno Merz ◽

Heiko Apel

Keyword(s):

Land Use ◽

Flood Risk ◽

Large Scale ◽

Flood Hazard ◽

Mekong Delta ◽

Flood Management ◽

Paddy Rice ◽

Rice Cultivation ◽

Spatially Explicit ◽

Risk Maps

Abstract. Flooding is an imminent natural hazard threatening most river deltas, e.g. the Mekong Delta. An appropriate flood management is thus required for a sustainable development of the often densely populated regions. Recently, the traditional event-based hazard control shifted towards a risk management approach in many regions, driven by intensive research leading to new legal regulation on flood management. However, a large-scale flood risk assessment does not exist for the Mekong Delta. Particularly, flood risk to paddy rice cultivation, the most important economic activity in the delta, has not been performed yet. Therefore, the present study was developed to provide the very first insight into delta-scale flood damages and risks to rice cultivation. The flood hazard was quantified by probabilistic flood hazard maps of the whole delta using a bivariate extreme value statistics, synthetic flood hydrographs, and a large-scale hydraulic model. The flood risk to paddy rice was then quantified considering cropping calendars, rice phenology, and harvest times based on a time series of enhanced vegetation index (EVI) derived from MODIS satellite data, and a published rice flood damage function. The proposed concept provided flood risk maps to paddy rice for the Mekong Delta in terms of expected annual damage. The presented concept can be used as a blueprint for regions facing similar problems due to its generic approach. Furthermore, the changes in flood risk to paddy rice caused by changes in land use currently under discussion in the Mekong Delta were estimated. Two land-use scenarios either intensifying or reducing rice cropping were considered, and the changes in risk were presented in spatially explicit flood risk maps. The basic risk maps could serve as guidance for the authorities to develop spatially explicit flood management and mitigation plans for the delta. The land-use change risk maps could further be used for adaptive risk management plans and as a basis for a cost–benefit of the discussed land-use change scenarios. Additionally, the damage and risks maps may support the recently initiated agricultural insurance programme in Vietnam.

Download Full-text

A metric-based assessment of flood risk and vulnerability of rural communities in the Lower Shire Valley, Malawi

Proceedings of the International Association of Hydrological Sciences ◽

10.5194/piahs-370-139-2015 ◽

2015 ◽

Vol 370 ◽

pp. 139-145 ◽

Cited By ~ 6

Author(s):

A. J. Adeloye ◽

F. D. Mwale ◽

Z. Dulanya

Keyword(s):

Rural Communities ◽

Spatial Variability ◽

Flood Risk ◽

Flood Hazard ◽

Sub Saharan Africa ◽

Structured Interviews ◽

Adaptation Measures ◽

Flood Depth ◽

Inundation Area ◽

Sub Saharan

Abstract. In response to the increasing frequency and economic damages of natural disasters globally, disaster risk management has evolved to incorporate risk assessments that are multi-dimensional, integrated and metric-based. This is to support knowledge-based decision making and hence sustainable risk reduction. In Malawi and most of Sub-Saharan Africa (SSA), however, flood risk studies remain focussed on understanding causation, impacts, perceptions and coping and adaptation measures. Using the IPCC Framework, this study has quantified and profiled risk to flooding of rural, subsistent communities in the Lower Shire Valley, Malawi. Flood risk was obtained by integrating hazard and vulnerability. Flood hazard was characterised in terms of flood depth and inundation area obtained through hydraulic modelling in the valley with Lisflood-FP, while the vulnerability was indexed through analysis of exposure, susceptibility and capacity that were linked to social, economic, environmental and physical perspectives. Data on these were collected through structured interviews of the communities. The implementation of the entire analysis within GIS enabled the visualisation of spatial variability in flood risk in the valley. The results show predominantly medium levels in hazardousness, vulnerability and risk. The vulnerability is dominated by a high to very high susceptibility. Economic and physical capacities tend to be predominantly low but social capacity is significantly high, resulting in overall medium levels of capacity-induced vulnerability. Exposure manifests as medium. The vulnerability and risk showed marginal spatial variability. The paper concludes with recommendations on how these outcomes could inform policy interventions in the Valley.

Download Full-text

Distribution of Flood Risk Area in Bodri Watershed of Kendal Regency

Sriwijaya Journal of Environment ◽

10.22135/sje.2021.6.2.59-69 ◽

2021 ◽

Vol 6 (2) ◽

pp. 59-69

Author(s):

Husna Fauzia ◽

◽

Eka Cahyaningsih ◽

Hery Hariyanto ◽

Satya Nugraha ◽

...

Keyword(s):

Land Use ◽

Spatial Modeling ◽

Flood Risk ◽

Flood Hazard ◽

Risk Level ◽

Flood Hazards ◽

Risk Area ◽

Flood Peak ◽

Risk Levels ◽

Central Java

Flooding is a catastrophic phenomenon that can occur due to various factors, such as uncontrolled landuse changes, climate change, and weather anomalies, and drainage infrastructure damage. The Bodri watershed in Kendal Regency is one of the watersheds in Central Java, which is categorized as critical based on Decree No.328/Menhut-II/2009. Some of the problems in the Bodri watershed include land use that is not suitable for its designation, flooding, erosion, and landslides. This study aims to conduct spatial modeling to create flood hazard maps and flood risk level maps in the Bodri watershed. The method used is hydrograph analysis, flood modeling, potential flood hazards, and flood risk levels. Analysis of the potential for flood hazards from the spatial modeling inundation map with the input of the flood peak return period of 2 years (Q2), 5 years (Q5), and 50 years (Q50). Vulnerability analysis based on land use maps of flood hazard areas. The distribution of flood-prone areas in the Bodri watershed is in Pidodo Kulon Village, Pidodo Wetan Village, and Bangunsari Village.

Download Full-text

An advanced method for flood risk analysis in river deltas, applied to societal flood fatality risks in the Netherlands

Natural Hazards and Earth System Sciences Discussions ◽

10.5194/nhessd-2-1637-2014 ◽

2014 ◽

Vol 2 (2) ◽

pp. 1637-1670 ◽

Cited By ~ 4

Author(s):

K. M. de Bruijn ◽

F. L. M. Diermanse ◽

J. V. L. Beckers

Keyword(s):

Risk Analysis ◽

Flood Risk ◽

Hydrodynamic Interaction ◽

Storm Surges ◽

Water Levels ◽

Analysis Framework ◽

Flood Risks ◽

River Deltas ◽

River Flood ◽

Flood Risk Analysis

Abstract. This paper discusses the new method developed to analyse flood risks in river deltas. Risk analysis of river deltas is complex, because both storm surges and river discharges may cause flooding and since the effect of upstream breaches on downstream water levels and flood risks must be taken into account. A Monte Carlo based flood risk analysis framework for policy making was developed, which considers both storm surges and river flood waves and includes hydrodynamic interaction effects on flood risks. It was applied to analyse societal flood fatality risks (the probability of events with more than N fatalities) in the Rhine–Meuse delta.

Download Full-text

Global River Flood Risk Under Climate Change

Wetland Carbon and Environmental Management - Geophysical Monograph Series ◽

10.1002/9781119427339.ch14 ◽

2021 ◽

pp. 251-270

Author(s):

Francesco Dottori ◽

Lorenzo Alfieri ◽

Lauro Rossi ◽

Roberto Rudari ◽

Philip J. Ward ◽

...

Keyword(s):

Climate Change ◽

Flood Risk ◽

River Flood

Download Full-text

A Generalized Framework for Assessing Flood Risk and Suitable Strategies under Various Vulnerability and Adaptation Scenarios: A Case Study for Residents of Kyoto City in Japan

Water ◽

10.3390/w12092508 ◽

2020 ◽

Vol 12 (9) ◽

pp. 2508

Author(s):

Bing-Chen Jhong ◽

Yasuto Tachikawa ◽

Tomohiro Tanaka ◽

Parmeshwar Udmale ◽

Ching-Pin Tung

Keyword(s):

Flood Risk ◽

Planning Process ◽

Climate Adaptation ◽

Adaptation Strategies ◽

Climate Risk ◽

Detention Ponds ◽

Kyoto City ◽

Generalized Framework ◽

Risk Maps ◽

Adaptation Scenarios

This study proposes a generalized framework for the assessment of flood risk and potential strategies to mitigate flood under various vulnerability and adaptation scenarios. The possible causes of hazard, exposure and vulnerability in flood disaster were clearly identified by using a climate risk template. Then, levels of exposure and vulnerability with adaptive capacity and sensitivity were further defined by a quantification approach, and the climate risk maps were consequently provided. The potential possible climate adaptation strategies were investigated through the comparison of climate risk maps with diverse adaptation options. The framework was demonstrated in the Kyoto City in Japan with residents as a target population to reduce the flood risk. The results indicate that the government should pay attention to reducing the population in flood-prone areas and adopt diverse adaptation strategies to reduce the flood risk to the residents. Rainwater storage and green roofs as adaptation strategies as short-term planning options are recommended. The construction of detention ponds has been suggested to prevent flood risks in future as a part of the long-term planning process. In conclusion, the proposed framework is expected to be a suitable tool for supporting climate risk analysis in the context of flood disasters.

Download Full-text

Assessing the Governance Context Support for Creating a Pluvial Flood Risk Map with Climate Change Scenarios: The Flemish Subnational Case

ISPRS International Journal of Geo-Information ◽

10.3390/ijgi9070460 ◽

2020 ◽

Vol 9 (7) ◽

pp. 460 ◽

Cited By ~ 1

Author(s):

Cesar Casiano Flores ◽

Joep Crompvoets

Keyword(s):

Climate Change ◽

Flood Risk ◽

Steering Committee ◽

Provincial Government ◽

Climate Change Scenarios ◽

Risk Map ◽

The Creation ◽

Risk Maps ◽

Flood Risk Map ◽

Subnational Governments

Climate change has increased pluvial flood risks in cities around the world. To mitigate floods, pluvial risk maps with climate change scenarios have been developed to help major urban areas adapt to a changing climate. In some cases, subnational governments have played a key role to develop these maps. However, governance research about the role of subnational governments in geospatial data development in urban water transitions has received little attention. To address this gap, this research applies the Governance Assessment Tool as an evaluative framework to increase our understanding of the governance factors that support the development of pluvial flood risk maps at the subnational level. For this research, we selected the region of Flanders in Belgium. This region is considered among the frontrunners when it comes to the creation of a pluvial flood risk map with climate change scenarios. Data have been collected through in-depth interviews with steering committee actors involved in the development process of the map. The research identified that the current governance context is supportive of the creation of the flood risk map. The government of Flanders plays a key role in this process. The most supportive qualities of the governance context are those related to the degree of fragmentation (extent and coherence), while the less supportive ones are those related to the “quest for control” (flexibility and intensity). Under this governance context, government actors play the primary role. The Flemish government led the maps’ creation process and it was supported by the lower governmental levels. As the provincial government was an important actor to increase local participation, collaboration with private and non-governmental actors in the steering committee was more limited. The financial resources were also limited and the process required a continuous development of trust. Yet, the Flemish Environmental Agency, with the use of technology, was able to increase such trust during the process.

Download Full-text