Non-structural Mitigation Measures Research Articles

FRAGILITY ANALYSIS OF DUNES REINFORCED WITH GEOSYNTHETIC SAND CONTAINERS

Encroachment of infrastructure on the natural beach system constrains dune volumes and necessitates construction of structural and nonstructural mitigation measures to improve coastal resilience. Nature-based solutions, such as dunes reinforced with geosynthetic sand containers (GSCs), are increasingly being used to stabilize coastlines and protect communities from smaller storm events (e.g. 50-year storms) while at the same time providing flexibility in design considering the uncertainty regarding rates of sea level rise and the increasing destructive power of storm events. Using risk-based hazard assessments, such as fragility curves, it is possible to quantify the resiliency of reinforced coastal systems to address these dynamic conditions. A fragility curve represents the conditional probability of failure of a coastal structure (e.g. natural dune, reinforced dune, seawall, etc.) as a function of a certain stress acting on the structure (typically water level, wave height/period; Gruhn et al. 2012). The main advantage of a fragility curve, compared to a damage function that quantifies a deterministic degree of damage directly to a stress, is that it can account for uncertainties in both the structural resistance (i.e. capacity) and the environmental stress (i.e. demand) of the system. The objective of this research is to present a fragility analysis of a U.S. Federally funded GSC-reinforced dune in Montauk, NY. This dune was constructed in 2016 and experienced significant erosion of the protective berm and sand covering the GSCs during a 1-year storm event that same year.

A Case Study on Watershed Study for Flood Mitigation of Belgavi Region, Karnataka, India using ArcGIS

During the monsoon season, many regions in India are prone to floods among which Belagavi district, Karnataka (the study area) is one of the most affected. It has suffered huge lives and property losses. This study focuses on areas of rainfall analysis, watershed area mapping, flood vulnerable areas mapping and possible mitigation measures. DEM analysis is used to understand flood risk assessment. The rainfall data is collected for three taluks which are more prone to flood. These are Athani, Chikodi, and Raibagh in Belgavi regions. The study area was analyzed by generating maps for soil type, lithology, geomorphology, land use, and land cover using ArcGIS software. Maps were obtained for the percentage of land contributing to each attribute. Further flood vulnerability mapping has to be done by creating weightage map considering factors such as drainage density, soil type,, precipitation, land use land cover, slope, and watershed compressed together by weighted overlay analysis, and the flood hazard zone map is developed to classify the areas into zones according to the risk of flooding which helps to suggest various non-structural mitigation measures.

Using non-structural mitigation measures to maintain business continuity: a multi-stakeholder engagement strategy

Encouraging property owners and individuals to adopt mitigation measures to improve the resilience of their buildings and equipments to seismic hazard has been a major challenge in many earthquake- prone countries. Few business leaders are aware of the fragility of their supply chains or other critical systems due to earthquake hazard. Bridging the gap between research production and research use is another crucial challenge for the earthquake risk research process. The KnowRISK project outcome is aimed at encouraging the proactive engagement of multi- stakeholders (community at large, schools, business community and local govern-ment groups) undertaking non-structural mitigation measures that will minimize earthquake losses to individuals and communities. Engaging stakeholders, taking into account their needs and inputs to maintain critical and urgent business activities, can contribute to the research findings and ensure that our data collection is thorough and complete. Engagement with stakeholders, during the whole process can lead to improved outcomes and for the development of viable solutions, for business and society, because of stakeholder’s role and influence within the organizations.

Flood risk forecasting at weather to medium range incorporating weather model, topography, socio-economic information and land use exposure

Non-structural mitigation measures to the globally increasing flood events include forecast based alert generation. However, the extreme rainfall forecasts are associated with low hit rate, high false alarm, and spatiotemporal bias; which makes it difficult to rely on them. Further, the losses due to flood in a region not only depend on rainfall severity but also on topography, socioeconomic conditions and exposure of the region to floods. Here, we introduce a new concept of spatial flood risk mapping and forecasting at weather to medium range based on forecasted hazard, embedded with vulnerability (topographic and socioeconomic) and exposure information. We define hazard as the probability of extreme rainfall event during upcoming days given an available weather forecast for the same days. As hindcast is used for computation of probabilities, hazard contains prior information about the false alarm, hit rate and spatiotemporal bias of the forecast. Vulnerability is calculated by averaging the topographic and socioeconomic indicators, and exposure is calculated using a land use land cover map. Topographic vulnerability is computed with digital elevation model using Height Above the Nearest Drainage method, and Data Envelopment Analysis is performed to derive the socioeconomic vulnerability based on the demographic census data. For a specific region and a specific event, the relative flood risk maps are generated at an administrative level (e.g., district, subdistrict or village level for India) and the high-risk areas can be identified from those maps for mitigation. The methodology is demonstrated for a very recent extremely severe flood event that happened in Kerala, India in August 2018. It is evident from the results that the high-risk areas forecasted well in advance (as high lead time as 15 days) match fairly well with the areas, which suffered maximum losses because of direct flood.

Flood Hazard Analysis on Dulecha Woreda Located in Middle Awash River Basin

Flood is a natural disaster and causes loss of life and property damage. Awash River is causing damage of farm land and other properties at Dulecha Woreda as it is located at flood plain area. The objective of the study is to analyze flood hazard of Dulecha Woreda located in Middle Awash River Basin. The hydrological modeling in combination with hydraulic modeling is used for this study. The HEC-HMS model simulated runoff for the storm event of 14 th July 1996 and 25 th August 2008 were respectively found to be 448.9 m 3 /s and 461.8 m 3 /s during calibration and validation period. HEC-HMS generated results during calibration and validation were used as input of unsteady flow analysis in HEC-RAS model. The hydraulic model calibration is performed with observed stage data after estimating representative Manning’s “n” for the study area. Manning’s roughness coefficient ‘n’ of 0.045 and 0.055 produced the best fit against the observed data for the river main channel and flood plain respectively and used for validation of HEC-RAS model. The flood inundation depth and area exported from HEC-RAS simulation of RAS Mapper has been processed by ArcGIS for further analysis of flood inundation map. The generated inundation map is the model prediction for the peak flow of year 2008 which is obtained from rainfall depth of 130.5 mm. The flood hazard extent which is obtained for 25-Aug-08 (0.001–3.51m) gave the maximum flood depth 3.51 m. Both structural and non-structural mitigation measures are recommended for the study area. Keywords: flood inundation mapping, flood depth, HEC-HMS; HEC-RAS, ArcGIS Cite this Article: Abeya Lencha, Fitsum Tesfaye. Flood Hazard Analysis on Dulecha Woreda Located in Middle Awash River Basin. International Journal of Water Resources Engineering. 2020; 6(1): 47–66p.

Rural Prospects for Resilience: Planning Sustainable Livelihoods and Coping with Flood Hazards along the U.S. Mississippi River

In this research, we examine the principles of social and economic resilience to flood hazards within the US Mississippi River Basin between 1990 and 2010. To address community response to natural hazards, we analyzed community resilience planning using integrated spatio-temporal modeling with content analysis and case study research. Triangulating empirical evidence from a mixed-methods approach allows contextual understanding of planning effectiveness with respect to rural community resilience. Results suggest that effort focused on coordinated and strategic planning acts to reduce adverse effects of natural hazards in hazard-prone counties. These strategies involve long-term planning, land use policies, structural mitigation, and nonstructural mitigation measures to reduce community vulnerability to flood risk thus advancing more sustainable rural livelihoods.

Disaster management strategy for avoiding the future losses by a slope failure at Nanhuan road, Fuxin area, Northeast China

Many surrounding areas in the vicinity of failed slope at Nanhuan road, Fuxin area, Northeast China are witnessed as the signs of disaster. The observed settlement as wastage of an active mass in the area has been observed after the excessive precipitation in 2012 (May to October) which caused infrastructural damages (Roads at the top and bottom of the failure zone), agricultural fields and residential areas. Therefore, the paper proposes examining this subject. An extensive field investigation was conducted in the area of Fuxin, west of Liaoning province China. It is recommended and suggested that a series of disaster prevention and both structural and non-structural mitigation measures with the involvement of government and local community are required, to be prepared in advance for avoiding the future economic loss as well as the impending disaster in the area. This paper also highlights the need of investigation in response mechanism and forward planning for awareness initiatives: to avoid the future hazard in the remotest failure zones of Fuxin area, Northeast China.

Flood insurance rate map for non-structural mitigation

December 2014 flooding in Kelantan river basin caused severe damage to economic and social infrastructure and dealt a serious blow to Kelantan state economies. Mitigation of flood disaster can be successful only when detailed knowledge is obtained about the vulnerability of the people, buildings, infrastructure and economic activities in a flood risk area. Therefore, to identify a community's flood risk, pre-disaster financial instrument will be introduced as non-structural mitigation measures know as flood insurance rate map. This instrument will be developed based on geospatial technology using satellite images, topographic surveys, cadastral map, type of community building such as residential or commercial and households’ income. Flood hazard maps and flood insurance rate map will provide the flood risk zone and flood insurance rate and premium coverage for the affected community. In additions it helps to determine the type of flood insurance coverage is needed since standard homeowners’ insurance doesn't cover flooding. Flood insurance rate map will provide affordable insurance for property owners, based on the lower the degree of risk state in flood hazard map, the lower the flood insurance premium. These insurance rate map are valuable to communities because it creates safer environments by reducing loss of life and decreasing property damage, allows individuals to minimize post-flood disaster disruptions and to recover quicker.

Sensitivity Analysis of Storm Duration for Development of Flood Map at Bertam Catchment, Cameron Highlands.

The current changes in climate have marked significant impacts in our daily weather. The changes have affected the trend, pattern and magnitude of rainfall-runoff as compared to the events commonly experienced. Flood is one of the effects of weather and climate change. Floods can be classified as one of the most devastating natural hazards and is a major concern to the country as it causes damages to human lives, environment, agriculture, land and structures. Therefore, effective flood planning and mitigation measures should be carried out in order to reduce the effects of flooding. Flood hazard map is one of the non-structural mitigation measures that can be used for planning purposes. Flood can be directly estimated or derived from frequency analysis when long duration of stream flow records is available. However, in the case of limited or no stream flow data available, design storm are generally used to estimate design flood. Downstream of Bertam Catchment is an ungauged river station where no flow records are available. Based on this limitation, in this study, design storm was used to design the flood map. Info Works RS was used to develop the flood model and sensitivity analysis of the design storm was performed. Results obtained in this study presented the comparison of flow between 100-years Annual Recurrence Interval (ARI) at various storm durations of 0.25hr, 0.5hr, 1hr, 3hrs, 6hrs, 12hrs, 1 day, 2days and 3 days. The maximum flow is found to be at 6hrs storm duration at 1103.418m3/s. Besides river flow, comparison of water level at 100-year ARI of various storm durations was also conducted. Results obtained from this study found that 24hrs storm duration will produce the highest water level at 1034.753m. By comparing the flow and water level, the result from river flow produces the maximum at 6hrs storm duration while the result of water level gives the maximum at 24hrs storm duration. Since, water level is preferable in producing flood hazard mapping at 2-D view, therefore, the storm duration is chosen based on results of sensitivity storm duration on water level conducted. Comparison is then conducted between 24-hrs storm duration at various ARIs. It can be concluded that 100-years ARI will lead to the maximum value of 1034.910m water level. Suitable storm duration and Annual Recurrence Interval (ARI) are to be determined in order to produce the best flood hazard map. In this study, it is found that 100-years ARI and 24hrs storm duration are the best combination, performed based on water level.

Hands-On Experience of Crowdsourcing for Flood Risks. An Android Mobile Application Tested in Frederikssund, Denmark.

There is evidence that the toll of death and destruction caused by natural hazards is rising. This is often ascribed to the impact of climate change that resulted in an increased frequency of extreme meteorological events. As a consequence, it is realistic to expect that the casualties and damages caused by floods will increase in the near future. Advanced weather forecast is a fundamental tool to predict the occurrence of floods and structural mitigation measures are crucial for flood protection. However, these strategies should be associate with tools to promote and increase natural-disaster awareness and nonstructural mitigation measures in the exposed population. To bridge this gap, we coupled innovative, ICT-based technologies with crowdsourcing. The idea is to exploit geospatial data gathered by citizens and volunteers with their own devices such as mobile phones to provide authorities with relevant information in case of flood emergencies. This paper describes the design and testing of an Android application named MAppERS (Mobile Applications for Emergency Response and Support), thought to enhance active participation and response of the population in territorial and flood-risk mitigation in Frederikssund, Denmark. The results of the piloting fully validate MAppERS as an effective tool to support the decision-making process during a crisis and to improve the awareness of the community and their disaster resilience.

Danish risk management plans of the EU floods directive

The paper evaluates the impact and effect of the EU Flood's Directive (2007/60/EC) in Denmark and the flood risk management plans that are the result of the national implementation in the first plan period (2010-2015). Twenty flood risk management plans have been elaborated and published by the 22 Danish municipalities included in 10 risk areas appointed due to a risk of floods from rivers, the sea, or both. For the municipal work, the national government has provided hazard, vulnerability, and risk assessments and maps as well as guidelines to fulfil the legal binding of the Directive. The plans are reviewed and analysed regarding main objectives and structural and non-structural mitigation measures. Conclusions point to the need of introducing better decision support systems, a need to define acceptable risks, and a need to enhance coordination between municipal and cross-sectorial actors as well as an increased effort to involve civil society is necessary. In general, the implementation of the Directive has significantly advanced the national scientific and cross-sectorial working platform for dealing with risks from floods.

Sustainable Hazard Mitigation: Exploring the Importance of Green Infrastructure in Building Disaster Resilient Communities

Natural disasters continue to plague the United States, undermining the nation’s ability to build disaster resilient communities. Although structural and non-structural mitigation measures are currently in place to lessen the impact natural disasters have on society, little attention has been given to the construction of green infrastructure as a sustainable hazard mitigation strategy. The purpose of this article is to explore the benefits of green infrastructure as a sustainable hazard mitigation strategy and offer recommendations to public sector entities to build disaster resilient communities.

The KULTURisk Regional Risk Assessment methodology for water-related natural hazards – Part 1: Physical–environmental assessment

Abstract. In recent years, the frequency of catastrophes induced by natural hazards has increased, and flood events in particular have been recognized as one of the most threatening water-related disasters. Severe floods have occurred in Europe over the last decade, causing loss of life, displacement of people and heavy economic losses. Flood disasters are growing in frequency as a consequence of many factors, both climatic and non-climatic. Indeed, the current increase of water-related disasters can be mainly attributed to the increase of exposure (elements potentially at risk in flood-prone area) and vulnerability (i.e. economic, social, geographic, cultural and physical/environmental characteristics of the exposure). Besides these factors, the undeniable effect of climate change is projected to strongly modify the usual pattern of the hydrological cycle by intensifying the frequency and severity of flood events at the local, regional and global scale. Within this context, the need for developing effective and pro-active strategies, tools and actions which allow one to assess and (possibly) to reduce the flood risks that threatens different relevant receptors becomes urgent. Several methodologies to assess the risk posed by water-related natural hazards have been proposed so far, but very few of them can be adopted to implement the last European Flood Directive (FD). This paper is intended to introduce and present a state-of-the-art Regional Risk Assessment (RRA) methodology to appraise the risk posed by floods from a physical–environmental perspective. The methodology, developed within the recently completed FP7-KULTURisk Project (Knowledge-based approach to develop a cULTUre of Risk prevention – KR) is flexible and can be adapted to different case studies (i.e. plain rivers, mountain torrents, urban and coastal areas) and spatial scales (i.e. from catchment to the urban scale). The FD compliant KR-RRA methodology is based on the concept of risk being function of hazard, exposure and vulnerability. It integrates the outputs of various hydrodynamic models with site-specific bio-geophysical and socio-economic indicators (e.g. slope, land cover, population density, economic activities etc.) to develop tailored risk indexes and GIS-based maps for each of the selected receptors (i.e. people, buildings, infrastructure, agriculture, natural and semi-natural systems, cultural heritage) in the considered region. It further compares the baseline scenario with alternative scenarios, where different structural and/or non-structural mitigation measures are planned and eventually implemented. As demonstrated in the companion paper (Part 2, Ronco et al., 2014), risk maps, along with related statistics, allow one to identify and classify, on a relative scale, areas at risk which are more likely to be affected by floods and support the development of strategic adaptation and prevention measures to minimizing flood impacts. In addition, the outcomes of the RRA can be eventually used for a further socio-economic assessment, considering the tangible and intangible costs as well as the human dimension of vulnerability.

기후변화시대 자연재해를 고려한 지속가능개발 개념의 재정립: 미국 방재동향 및 사례 분석을 중심으로

본 연구는 기후변화로 인하여 심각해져가고 있는 자연재해에 보다 효율적인 대응방안을 마련하기 위한 이론적 토대를 확립하고자 도시계획분야의 지속가능성 개념을 재정립하였다. 과거 지속가능성 개념에 대한 고찰과 최근 미국 방재학계의 동향을 분석하여 마련한 새로운 지속가능개발은 기존 환경분야 주요 목표인 환경보호와 더불어 이상기후로부터 도시 사회 안전성 확보가 포함되어야 함을 인식하였다. 그리고 도시 사회 안전성 확보는 저탄소녹색도시 관련요소와의 연계 속에서 이뤄져야 함을 강조하였다. 또한 환경, 경제, 사회분야의 목표를 동시에 추구함으로써 야기되는 갈등을 인식하고 대형화된 자연재해에 효과적으로 대응하기 위하여 기존 공학 시설중심의 구조적 방재대책과 더불어 비구조적 대책의 적극적 도입 필요성을 제시하였다. 본 연구에서 제시한 이론적 틀을 바탕으로 도시계획분야의 향후 연구는 갈등 조정 중재를 위한 새로운 제도적 틀 마련과 함께 APFM(the Associated Programme on Flood Management)에서 제시한 '노출(Exposure)'과 '취약성(Vulnerability)' 요인을 바탕으로 환경보호와 안전성 확보는 물론 관련 갈등해소에 기여할 수 있는 세부 요소 목표설정, 구체적 관련 기술개발 등에 노력해야 할 것으로 판단된다. The main purpose of this study is to reframe sustainability or sustainable development concept in the field of planning in consideration of climate change and natural hazards. The new concept is expected to provide a theoretical foundation for upcoming hazard mitigation measures addressing climate change. The first and main argument of the new concept is that environmental protection should be inclusive enough to address urban (or community) security from current natural hazards. The second is that the balance between structural and nonstructural mitigation measures is critical to cope more effectively with extreme natural hazards in the era of climate change and also with conflicts driven by three goals of sustainability--environmental protection, economic development, and social justice. The following studies, based on this new concept of sustainablity, are expected (1) to address new participation methods for the conflict resolution, (2) to explore detailed and substantive planning strategies and creative technical and institutional solutions for environmental protection, natural hazard mitigation, and conflict resolution. Two of APFM(the Associated Programme on Flood Management)'s three natural hazard risk criteria, Exposure and Vulnerability, may guide the exploration.

Flood Control and Drainage, Water Supply and Sewerage: Managing Water in Both Excess and Scarcity

The first part of this paper draws the lessons for flood management from the experience of the recent major flooding events of 2009 TS Ketsana (Ondoy), 2009 TS Panna (Peping) in Luzon, and the adverse impacts of 2011 TS Sendong on Visayas and Mindanao. NDRRMC data are analyzed in terms of the relative intensities and distribution of population impacts (killed, injured, missing) and economic damages reported among the different storms and regions of impacts. The paper emphasizes the need for implementing structural mitigation measures in poor unprotected towns and regions in the country, as part of an adaptation strategy, under the challenge and threat posed by growing population and anticipated climate change. Likewise, non-structural mitigation measures (which have shorter gestation periods of months and few years only, compared to decades for major structural measures) must also be provided under the imperative or necessity implied by the quantified "structural gap" of existing structures to adequately reduce and effectively manage the increasing flood hazard risks caused by growing population and climate change. In the second part of this paper dealing with water supply and sewerage (sanitation), recent NEDA and ADB reports were cited which make very clear the necessity that the Philippines has to achieve a faster rate of providing access to improved sanitation facilities, at a rate at par with that of providing access to improved drinking water, in the quest of the country to attain the "early achiever" status before 2015 in both water supply and sanitation targets. After all, the improvement of water supply facilities brings in the potential for producing higher volumetric rates of wastewater. The needs for wastewater treatment (and possible reuse of treated water) are met in the medium term by septage truck-collection and septage plant treatment (in Metro Manila, for example), but better in the longer term with piped sewerage collection networks and sewage treatment plants in both developed and developing communities and towns nation-wide. It is strongly recommended that new programs and projects in water supply development be accompanied with parallel and coupled sewerage (sanitation) programs and projects. This two-part article deals with the two important sub-sectors of the water sector: namely, flood control & drainage (flood management), on one hand, and water supply & sewerage (or sanitation) on the other hand. The article aims to explain and share with the general reading public the results of a long series of round-table discussions (RTDs), research studies, and annual scientific meetings held in the period 2009-2012, organized by the National Academy of Science & Technology (NAST) of the Philippines in pursuit of its policy-making and advisory mission and function to the nation. These fora and activities were done also with the cooperation and support of the UNESCO National Commission, national government agencies (NGAs such as NEDA, NWRB, DPWH, DENR and DOST), NGCCs (MWSS, water districts, etc.), NGOs (PWP and professional societies), the academe (UP Diliman, Mapua (MIT) and Manila Observatory-Ateneo), and representatives of certain LGUs and the private sector (such as MWCI, MWSl, and consulting firms). In addition lo the consensus established and recommended in the various water fora, the personal views and recommendations of the author are also indicated where they help in clarification of issues or demonstration of solutions. The other major sub-sectors of irrigation, hydropower and other water uses may be covered in future articles by other writers among the academicians of NAST.

The 2007 flood in Tabasco, Mexico: an integral analysis of a devastating phenomenon

A markedly intense rain fell on southeastern Mexico during the period of 29 October–1 November 2007. As a result, the state of Tabasco recorded the gravest flood in the last 50 years. A reconstruction of the event is presented, including the identification of the factors that aggravated the sequels, and a discussion of the actions that were carried out to evaluate the flooding. The phenomenon consisted of a succession of rains in the region, including 3 days of continuous rain with over 403 mm d−1. The operation of a system of dams, the saturation of the soil, and runoff times below 16 h were the factors that generated the catastrophe, in synergy with the meteorological phenomenon. The analysis presented here will aid in understanding the development of the phenomenon in an integral way, and in establishing the minimum procedures to be followed to evaluate similar events in other regions where, as in Mexico, one does not have timely access to information. In the case of this disaster, for example, different versions of the causes of the flood continued to circulate 6 months after it took place, some lacking technical bases and some access-restricted. However, the information generated provided the academic community and state officials with a reference on which to evaluate the event. This analysis also makes a contribution by placing emphasis on the need to establish non-structural mitigation measures such as future urban growth and regulation plans and future early warning systems against flooding, monitoring the variables that were analysed and generating products useful to the decision-makers involved in civil protection systems and in carrying out preventive measures to mitigate the effects of extreme events.