Evaluation of adapted hydrological flood routing approaches as a cost-efficient contribution for the assessment of nature-based flood mitigation measures

Nature-based retention measures are an essential part of a sustainable and integrated flood protection strategy and can contribute to a holistic flood mitigation approach. Thereby river restoration measures such as channel widening, or flow path extension to increase the channel meandering represent successfully used components. Coupled with flood plain measures, retarding and retention effects of flood events are possible. These effects are commonly computed applying two-dimensional hydrodynamic modelling approaches. However, these developments rely on high spatial and temporal resolutions which are generally characterized by a high computational demand and are hence time and cost expensive. Thus, the evaluation and derivation of flood routing parameters to reproduce the resulting hydrodynamical processes in hydrological models can provide an effective and fast computation of river restoration scenarios.&#160;The objective in the present study is the derivation and application of flood routing parameters which can account for the effects of river restoration and flood plain measures in hydrological models. Further, this study aims to determine if the catchment and scale specific outcomes and parameter sets are also applicable to a broader range of catchments.For this purpose, commonly applied flood routing approaches and the associated parameters used in hydrological models (e.g. the kinematic wave approach in the WaSiM model) are investigated for catchments of different scales in Bavaria (Germany) and for flood events of varying characteristics (e.g. return period, flood volume). To determine the effects of channel restoration and flood plain measures, two-dimensional hydrodynamic models (HYDRO_AS-2D) are set up to simulate the current state as well as restoration scenarios. Based on the simulation results of the hydrodynamic models, the parameters of the flood routing approaches are calibrated to match the catchment specific restoration effects for a first set of river sections. Catchment and scale dependent parameter sets (dominating valley type, flood plain slopes) are then derived to reproduce the specific river restoration. First results of the calibration of the parameter sets show a satisfying fit of the hydrological model to different restoration scenarios of the hydrodynamic model. For the validation of the derived parameter sets of the flood routing methods in the hydrological model additional river sections of the hydrodynamic models are subsequently investigated.The implementation of the new flood routing parametrization of the hydrological models is finally examined as an alternative resource efficient way of calculating the effects of river restoration scenarios. Moreover, the applicability of the outcomes as a cost-efficient alternative compared to hydrodynamic models in land use planning and risk assessment is assessed and discussed within the frame of river restorations as flood mitigation measures.

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A Conflict between Traditional Flood Measures and Maintaining River Ecosystems? A Case Study Based upon the River Lærdal, Norway

Water ◽

10.3390/w13141884 ◽

2021 ◽

Vol 13 (14) ◽

pp. 1884

Author(s):

Ana Juárez ◽

Knut Alfredsen ◽

Morten Stickler ◽

Ana Adeva-Bustos ◽

Rodrigo Suárez ◽

...

Keyword(s):

Remote Sensing Data ◽

Freshwater Ecosystems ◽

River Channel ◽

Flood Mitigation ◽

Mitigation Measures ◽

Flood Events ◽

Protection Measures ◽

River Ecosystems ◽

Hydraulic Models

Floods are among the most damaging of natural disasters, and flood events are expected to increase in magnitude and frequency with the effects of climate change and changes in land use. As a consequence, much focus has been placed on the engineering of structural flood mitigation measures in rivers. Traditional flood protection measures, such as levees and dredging of the river channel, threaten floodplains and river ecosystems, but during the last decade, sustainable reconciliation of freshwater ecosystems has increased. However, we still find many areas where these traditional measures are proposed, and it is challenging to find tools for evaluation of different measures and quantification of the possible impacts. In this paper, we focus on the river Lærdal in Norway to (i) present the dilemma between traditional flood measures and maintaining river ecosystems and (ii) quantify the efficiency and impact of different solutions based on 2D hydraulic models, remote sensing data, economics, and landscape metrics. Our results show that flood measures may be in serious conflict with environmental protection and legislation to preserve biodiversity and key nature types.

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Parameter optimization in modelling unsteady compound channel flows

Canadian Journal of Civil Engineering ◽

10.1139/l92-053 ◽

1992 ◽

Vol 19 (3) ◽

pp. 441-446 ◽

Cited By ~ 3

Author(s):

Habib Abida ◽

Ronald D. Townsend

Keyword(s):

Parameter Optimization ◽

Optimization Methods ◽

Flood Plain ◽

Flood Routing ◽

Compound Channel ◽

Flood Events ◽

Channel Section ◽

Simplex Methods ◽

Boundary Roughness ◽

Good Agreement

Optimization methods are used to estimate data for routing floods through open compound channels (main channels with flood plain zones). These data include the irregular channel section geometry and the varying boundary roughness. Differences between simulated and observed stages and discharges are minimized using three optimization algorithms: Powell's method, Rosenbrock's algorithm, and the Nelder and Meade simplex method. Powells' method performed poorly; however, both the Rosenbrock and simplex methods yielded good results. The estimated data using the Rosenbrock and simplex methods were used to route different flood events observed in a laboratory channel. Simulated peak stages and discharges were in good agreement with those estimated using actual routing data. Key words: compound channel, flood routing, lateral momentum transfer, optimization, unsteady flow.

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Flood Mitigation Techniques—A New Perspective for the Case Study of Adayar Watershed

10.20944/preprints201712.0135.v1 ◽

2017 ◽

Author(s):

Vidyapriya V. ◽

Ramalingam M.

Keyword(s):

Drainage System ◽

Flood Mitigation ◽

Storm Water ◽

Mitigation Measures ◽

Complex Nature ◽

Adjacent Area ◽

Drainage Network ◽

Flood Events ◽

Water Drainage ◽

Impervious Area

Mostly populous city like Chennai is subjected to frequent flooding due to its complex nature of natural and man-made activities. From the analysis of the past records of flood events of 1943,1976,1985,2005 and 2008,it has been observed Adayar watershed is subjected to cataclysmic flooding in low-lying areas of the city and its suburbs because of inoperativeness of the local drainage system, rainfall associated with cyclonic activity, topography of the terrain, encroachments along the floodplain, hugh upstream flow discharge into the river and the highly impervious area which blocked the runoff to flow into the storm water drainage. After looking into these problems of flooding, a study have been conducted on Adayar watershed to develop a 2D hydrodynamic model for the two scenarios of existing condition of storm water drainage network and revised conditions of storm water drainage network using high resolution Lidar DEM to assess the volume of runoff with respect to time and duration on flood peaks for the two flood events of 2005 and 2015.Secondly to develop a 1D flood model to predict the river stages during peak floods using MIKE 11 for the Adayar watershed. Thirdly to integrate the coupled 1D and 2D model using MIKEFLOOD for assessing the extent of inundation in the floodplain area of Adayar river. Finally results from the integrated model have been validated and the results found satisfactory. As a part of mitigation measures, two flood mitigation measures have been adopted. One measure such as revised storm water drainage system which enhances the flood carrying capacity of the drains and results in less inundated area which solves the problem of urban flooding and second measure such as regrading the river bed which reduces the floodplain inundation around the adjacent area of the river. After adopting these measures, the river is free to flow into the sea without any blockades.

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A Cost-Effectiveness Protocol for Flood-Mitigation Plans Based on Leeds’ Boxing Day 2015 Floods

Water ◽

10.3390/w12030652 ◽

2020 ◽

Vol 12 (3) ◽

pp. 652 ◽

Cited By ~ 1

Author(s):

Onno Bokhove ◽

Mark A. Kelmanson ◽

Thomas Kent ◽

Guillaume Piton ◽

Jean-Marc Tacnet

Keyword(s):

Cost Effectiveness ◽

Flood Plain ◽

Flood Management ◽

Cost Effectiveness Analysis ◽

City Council ◽

Flood Mitigation ◽

Mitigation Measures ◽

Wide Audience ◽

Effectiveness Analysis ◽

River Bed

Inspired by the Boxing Day 2015 flood of the River Aire in Leeds, UK, and subsequent attempts to mitigate adverse consequences of flooding, the goals considered are: (i) to revisit the concept of flood-excess volume (FEV) as a complementary diagnostic for classifying flood events; (ii) to establish a new roadmap/protocol for assessing flood-mitigation schemes using FEV; and, (iii) to provide a clear, graphical cost-effectiveness analysis of flood mitigation, exemplified for a hypothetical scheme partially based on actual plans. We revisit the FEV concept and present it as a three-panel graph using thresholds and errors. By re-expressing FEV as a 2 m -deep square lake of equivalent capacity, one can visualise its dimensions in comparison with the river valley considered. Cost-effectiveness of flood-mitigation measures is expressed within the FEV square-lake; different scenarios of our hypothetical flood-mitigation scheme are then presented and assessed graphically, with each scenario involving a combination, near and further upstream of Leeds, of higher (than existing) flood-defence walls, enhanced flood-plain storage sites, giving-room-to-the-river bed-widening and natural flood management. Our cost-effectiveness analysis is intended as a protocol to compare and choose between flood-mitigation scenarios in a quantifiable and visual manner, thereby offering better prospects of being understood by a wide audience, including citizens and city-council planners. Using techniques of data analysis combined with general river hydraulics, common-sense and upper-bound estimation, we offer an accessible check of flood-mitigation plans.

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Comment on "Significance of "high probability/low damage" versus "low probability/high damage" flood events" by Merz et al. (2009)

Natural Hazards and Earth System Science ◽

10.5194/nhess-10-1-2010 ◽

2010 ◽

Vol 10 (1) ◽

pp. 1-2 ◽

Cited By ~ 8

Author(s):

C. M. Rheinberger

Keyword(s):

Risk Aversion ◽

Natural Hazards ◽

High Probability ◽

Flood Mitigation ◽

Mitigation Measures ◽

Flood Events ◽

Flood Risks ◽

Relative Damage ◽

Low Probability

Abstract. This comment is meant to shed some light on the use of so-called "risk aversion functions" in the management of flood risks and other natural hazards as recently proposed in this journal (Merz et al., 2009). In particular, I resume the discussion as to whether the relative damage is a suitable indicator of risk aversion and lay out why the use of this indicator may lead to inefficient decisions upon flood mitigation measures.

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Socio–Economic Analysis of Riverine Flooding on Low-Income Dwellings: Adayar River, a Case Study

Civil and Environmental Engineering Reports ◽

10.2478/ceer-2020-0024 ◽

2020 ◽

Vol 30 (2) ◽

pp. 133-157

Author(s):

Suriya Saravanan ◽

Mudgal Basavaraj ◽

Prakash Nelliyat

Keyword(s):

Low Income ◽

Flood Plain ◽

Flood Damage ◽

Vital Role ◽

Flood Mitigation ◽

Mitigation Measures ◽

Structured Interviews ◽

The Impact ◽

Sustainable Mitigation

AbstractFlood damage assessment plays a vital role in providing information to policy developers. Nowadays, due to urbanization, the impact of flooding on communities is extensive, including tangible damage to property, the environment, and infrastructure as well as intangible damage due to stress, health hazards, and hardship. This paper provides an overview of a detailed flood assessment study conducted in the Kotturpuram Housing board area, located on the flood plain of the Adayar River in Chennai, India. A relatively simple approach to data collection was adopted, being a Questionnaire Survey (QS) as well as semi-structured interviews and observation techniques, due to data and research limitations. Losses due to damage to belongings and extra spending to buy essential commodities during flooding are also dealt with in this study. The flood mitigation costs for flooding that occurred in the year 2015 are also evaluated. A stage-damage curve was arrived at based on the information collected. Optimal and sustainable mitigation measures can be achieved only when the socio-economic aspects are adequately considered. Thus, this analysis was designed to estimate the effects of flooding on a community’s social and economic welfare, and thereby help to educate the community, including residents and officials, about the impact and magnitude of flooding. The outputs of the study will be the key inputs for designing flood mitigation and relief measures.

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Reply to Comment on "Significance of "high probability/low damage" versus "low probability/high damage" flood events" by C. M. Rheinberger (2009)

Natural Hazards and Earth System Science ◽

10.5194/nhess-10-3-2010 ◽

2010 ◽

Vol 10 (1) ◽

pp. 3-5 ◽

Cited By ~ 3

Author(s):

B. Merz ◽

F. Elmer ◽

A. H. Thieken

Keyword(s):

Decision Making ◽

Risk Aversion ◽

High Probability ◽

Flood Mitigation ◽

Mitigation Measures ◽

Flood Events ◽

Relative Damage ◽

Low Probability ◽

Published Paper

Abstract. In a comment to our recently published paper on the "Significance of "high probability/low damage" versus "low probability/high damage" flood events" (Merz et al., 2009), C. M. Rheinberger questions the use of relative damage as a suitable indicator for risk aversion and the use of the resulting risk aversion functions in judging flood mitigation measures. While the points of criticism are important and should be accounted for, most of these points are considered in our original paper. More importantly, we do not agree with the conclusion that the use of relative damage as indicator for risk aversion is generally not appropriate in decision making about flood mitigation measures.

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Long-term development and effectiveness of private flood mitigation measures: an analysis for the German part of the river Rhine

Natural Hazards and Earth System Science ◽

10.5194/nhess-12-3507-2012 ◽

2012 ◽

Vol 12 (11) ◽

pp. 3507-3518 ◽

Cited By ~ 81

Author(s):

P. Bubeck ◽

W. J. W. Botzen ◽

H. Kreibich ◽

J. C. J. H. Aerts

Keyword(s):

Flood Damage ◽

Flood Risk Management ◽

Flood Mitigation ◽

Mitigation Measures ◽

Flood Events ◽

Private Households ◽

Integrated Flood Risk Management ◽

German Part ◽

Over Time

Abstract. Flood mitigation measures implemented by private households have become an important component of contemporary integrated flood risk management in Germany and many other countries. Despite the growing responsibility of private households to contribute to flood damage reduction by means of private flood mitigation measures, knowledge on the long-term development of such measures, which indicates changes in vulnerability over time, and their effectiveness, is still scarce. To gain further insights into the long-term development, current implementation level and effectiveness of private flood mitigation measures, empirical data from 752 flood-prone households along the German part of the Rhine are presented. It is found that four types of flood mitigation measures developed gradually over time among flood-prone households, with severe floods being important triggers for an accelerated implementation. At present, still a large share of respondents has not implemented a single flood mitigation measure, despite the high exposure of the surveyed households to floods. The records of household's flood damage to contents and structure during two consecutive flood events with similar hazard characteristics in 1993 and 1995 show that an improved preparedness of the population led to substantially reduced damage during the latter event. Regarding the efficiency of contemporary integrated flood risk management, it is concluded that additional policies are required in order to further increase the level of preparedness of the flood-prone population. This especially concerns households in areas that are less frequently affected by flood events.

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CSO Modelling Considering Moving Storms and Tipping Bucket Gauge Failures

Water Practice & Technology ◽

10.2166/wpt.2007.024 ◽

2007 ◽

Vol 2 (1) ◽

Cited By ~ 1

Author(s):

M. Hochedlinger ◽

W. Sprung ◽

H. Kainz ◽

K. König

Keyword(s):

Hydrological Models ◽

Rain Intensity ◽

Hydrodynamic Models ◽

Data Intensive ◽

Storm Flow ◽

Cell Velocity ◽

Combined Sewer ◽

Moving Direction ◽

The Difference

The simulation of combined sewer overflow volumes and loads is important for the assessment of the overflow and overflow load to the receiving water to predict the hydraulic or the pollution impact. Hydrodynamic models are very data-intensive and time-consuming for long-term quality modelling. Hence, for long-term modelling, hydrological models are used to predict the storm flow in a fast way. However, in most cases, a constant rain intensity is used as load for the simulation, but in practice even for small catchments rain occurs in rain cells, which are not constant over the whole catchment area. This paper presents the results of quality modelling considering moving storms depending on the rain cell velocity and its moving direction. Additionally, tipping bucket gauge failures and different corrections are also taken into account. The results evidence the importance of these considerations for precipitation due the effects on overflow load and show the difference up to 28% of corrected and uncorrected data and of moving rain cells instead of constant raining intensities.

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