Physical Vulnerability Curves Research Articles

Development of structural type-based physical vulnerability curves to debris flow using numerical analysis and regression model

Urbanization has significantly increased the risk of debris flows to houses located at mountain boundaries, particularly in South Korea, where urban centers are surrounded by mountains. The degree of damage to a house strongly depends on the structural rigidity of the building, even when exposed to the same hazard intensities. However, the structural characteristics of buildings are usually disregarded in vulnerability assessments. In this study, vulnerability curves were proposed for three different structural types of buildings: brick masonry, light-weight steel frame, and wood structures, using numerical and regression analyses. A total of 22 debris flow events from 2011 to 2020 and 63 cases of damage to unreinforced structures were collected and analyzed. Back analysis of the debris flows was performed using Flow-R, and the impact pressure acting on each structure was calculated. Three different vulnerability curves were proposed using various linear and nonlinear regression analyses; the Avrami equation provided the highest statistical significance. The vulnerability curves of three different structures were similar for the slight damage range. However, over the slight damage range, the wood structure was the most vulnerable at a given hazard intensity, whereas the brick masonry structure was the least vulnerable. Validation was performed using data from recent debris flow events, revealing precise damage level predictions for 9 out of 11 buildings. Compared with previous research, the degree of damage at the same hazard intensity was found to be significantly dependent on the structural type. The developed vulnerability curve for each unreinforced structure can be used as key data for vulnerability and risk assessments.

Physical vulnerability curve construction and quantitative risk assessment of a typhoon-triggered debris flow via numerical simulation: A case study of Zhejiang Province, SE China

Physical vulnerability curve construction and quantitative risk assessment of a typhoon-triggered debris flow via numerical simulation: A case study of Zhejiang Province, SE China

Development of Physical Vulnerability Curve based on Debris Flow Events

In recent years, owing to climate change various slope disasters are rising. Debris flow causes large damage to human life and social infrastructure. Generally, the vulnerability assessment of slope disasters is carried out using vulnerability curve, which consists of hazard intensity and damage index. A vulnerability curve needs to be highly reliable. In this study, GIS-based topographical characteristics and the information about 27 debris flow events that occurred between 2011 and 2020 were collected and analyzed. The hazard intensity of the debris flow events was evaluated considering entrainment of soils and buildings. Two types of buildings, non-reinforced concrete structure (non-RC) and reinforced concrete structure (RC frame) were classified into four types of vulnerability indices (slight, moderate, extensive, and complete) based on the degree of damage to the building. The relationship between the hazard intensity and the degree of damage to the building was studied through nonlinear regression analysis to derive a vulnerability curve according to the hazard intensity. The proposed vulnerability curve can be used as fundamental data for the vulnerability assessment of landslide disasters.

Assessment of the physical vulnerability of buildings affected by slow-moving landslides

Abstract. Physical vulnerability is a challenging and fundamental issue in landslide risk assessment. Previous studies mostly focus on generalized vulnerability assessment from landslides or other types of slope failures, such as debris flow and rockfall, while the long-term damage induced by slow-moving landslides is usually ignored. In this study, a method was proposed to construct physical vulnerability curves for masonry buildings by taking the Manjiapo landslide as an example. The landslide's force acting on the buildings' foundation is calculated by applying the landslide residual-thrust calculation method. Considering four rainfall scenarios, the buildings' physical responses to the thrust are simulated in terms of potential inclination by using Timoshenko's deep-beam theory. By assuming the landslide safety factor to be landslide intensity and inclination ratio to be vulnerability, a physical vulnerability curve is fitted and the relative function is constructed by applying a Weibull distribution function. To investigate the effects of buildings' parameters that influence vulnerabilities, the length, width, height, and foundation depth and Young's modulus of the foundation are analysed. The validation results on the case building show that the physical vulnerability function can give a good result in accordance with the investigation in the field. The results demonstrate that the building length, width, and foundation depth are the three most critical factors that affect the physical vulnerability value. Also, the result shows that the higher the ratio of length to width of the building, the more serious the damage to the building. Similarly, the shallower the foundation depth is, the more serious the damage will be. We hope that the established physical vulnerability curves can serve as tools for the quantitative risk assessment of slow-moving landslides.

Coastal Flooding Risk Assessment Using a GIS-Based Spatial Multi-Criteria Decision Analysis Approach

Coastal areas are expected to be at a higher risk of flooding when climate change-induced sea-level rise (SLR) is combined with episodic rises in sea level. Flood susceptibility mapping (FSM), mostly based on statistical and machine learning methods, has been widely employed to mitigate flood risk; however, they neglect exposure and vulnerability assessment as the key components of flood risk. Flood risk assessment is often conducted by quantitative methods (e.g., probabilistic). Such assessment uses analytical and empirical techniques to construct the physical vulnerability curves of elements at risk, but the role of people’s capacity, depending on social vulnerability, remains limited. To address this gap, this study developed a semiquantitative method, based on the spatial multi-criteria decision analysis (SMCDA). The model combines two representative concentration pathway (RCP) scenarios: RCP 2.6 and RCP 8.5, and factors triggering coastal flooding in Bandar Abbas, Iran. It also employs an analytical hierarchy process (AHP) model to weight indicators of hazard, exposure, and social vulnerability components. Under the most extreme flooding scenario, 14.8% of flooded areas were identified as high and very high risk, mostly located in eastern, western, and partly in the middle of the City. The results of this study can be employed by decision-makers to apply appropriate risk reduction strategies in high-risk flooding zones.

Rice drought risk assessment under climate change: Based on physical vulnerability a quantitative assessment method

Drought is the most serious natural disaster causing severe damage to agriculture. Drought impacts on rice (Oryza sativa) production present a major threat to future global food security. In this paper, the Environmental Policy Integrated Climate (EPIC) model was used to simulate the growth of rice, in different periods (short-term (2019–2039), medium-term (2040–2069), long-term (2070–2099)), based on multiple Representative Concentration Pathways (RCP) scenarios. Drought intensity and rice physical vulnerability curves were assessed, based on the output parameters of EPIC, to evaluate global rice yield risk, due to drought. The results show that the average expected loss rate of global rice yield may reach 13.1% (±0.4%) in the future. The high-risk area of rice drought is mainly located in the north of 30°N. The fluctuation of rice drought risk and the proportion of increased risk areas will increase significantly. About 77.6% of the changes in rice drought risk are explained by variations in shortwave radiation (r = 0.88). Projections show that the average value of daily shortwave radiation increases by 1 W/m2 during the rice growth period, accompanied by an expected rice yield loss rate of about 12.7%. The rice drought risk methods presented in this paper provide plausible estimates of forecasting future drought risk under climate change, and address challenges of sparse data; we believe these methods can be applied to decisions for reducing drought-related crop losses and ensuring global food security.

A reliability-based approach for the impact vulnerability assessment of bridge piers subjected to debris flows

Bridge piers are typically among the most vulnerable structural members subjected to debris flows. This paper proposes a reliability-based approach based on a nonlinear structural analysis to determine the physical vulnerability curves associated with bridge piers given exposure to debris flow impact. Relevant aleatory and epistemic uncertainties in both hazard and structure are incorporated in the method with the inclusion of a fully probabilistic framework. The high- and low-viscosity debris flows are assessed as being representative of two classes of debris flow for their different load patterns. The load effect on a pier column is considered as the combined effect of slurry and boulder impact, which can be characterized, respectively, by Poisson square wave process and Poisson impulse process. A quantitative displacement-based damage index is defined considering the possible failure modes of the pier column. Using a Monte Carlo simulation, a set of vulnerability curves relative to different hazard intensity measures for high- and low-viscosity debris flow is derived and sensitivity studies are conducted to estimate the influences of hazard inputs. The proposed methodology addresses the geographical restrictions of conventional empirical debris flow vulnerability models and provides a general approach for quantitative risk assessment in hazard-prone areas, thereby forming a basis for subsequent engineering design or risk zoning.

Drought disaster risks under CMIP5 RCP scenarios in Ningxia Hui Autonomous Region, China

The Ningxia Hui Autonomous Region of China (Ningxia), one of main agriculture areas in northwest China, has been severely affected by drought. Based on observed meteorological data, outputs of 20 global climate models and drought disaster data, future climate change and relevant drought hazard in the twenty-first century were projected in Ningxia, with the scenarios of RCP2.6 and RCP4.5; the risks of people, crop, and agriculture economy to drought disasters are quantitatively assessed, with the application of physical vulnerability curve models, probability distribution functions and Monte Carlo simulation method. It is found that the climate in Ningxia is likely to have a warming and wetting tendency in the twenty-first century. The extent of drought hazard is likely to increase. The increase rate is greater under RCP4.5 than that under RCP2.6. In general, the risks of population, crop, and agriculture to drought disasters are likely to increase in Ningxia in the twenty-first century. The magnitude of increase is likely to reach the greatest in the immediate term (2016–2035), followed by the increase in the medium term (2046–2065), and the long term (2081–2100). In comparison with RCP2.6, the drought disaster risks under the scenario of RCP4.5 are likely to increase further in three periods of the twenty-first century. The findings of this work have potential to provide data support for drought disaster risk management and support risk-based decision-making.

Dynamic drought risk assessment for maize based on crop simulation model and multi-source drought indices

Agricultural drought is a globally impacted natural disaster for the rain-fed agriculture region. The aim of this study is to construct a dynamic drought risk assessment (DDRA) model of maize for different growth periods based on risk assessment theory. In this model, optimal drought hazard indices for maize of the four growth stages were selected among 11 time scales daily Standardized Precipitation Evapotranspiration Index, Precipitation Condition Index, Soil Moisture Condition Index, Vegetation Condition Index, and Optimized Vegetation Drought Index. Secondly, the CERES-Maize model was used to fit the physical vulnerability curves with their corresponding drought hazards indices. DDRA model of maize in Jilin Province, China during 1981–2014 was conducted based on in situ data, remote sensing data, and field experiments data. The maize drought risk series maps were drawn and the results showed that the risk value under same hazard level presented an increasing trend at emergence-jointing and jointing-heading stage, and had a slight decreasing trend at heading-milky and milky-mature stage. For spatial dimension, the high drought risk value was distributed in the west and middle region. During the last three growth periods, the high risk value areas increased gradually from northwest to southeast region. The results indicated that the DDRA model provides more accurate evaluation in both the time and spatial scale and has significant guidance value for improving the adaptability of agricultural drought risk.

Physical vulnerability models for assessing building damage by debris flows

A catastrophic debris flow occurred in Zhouqu County, Gansu Province, Northwestern China, at midnight on 7 August 2010, resulting in damage to >390 buildings. Assessment of the vulnerability of buildings to debris flow hazards is essential to quantify the risk of debris flows. This paper presents a new family of physical vulnerability curves to assess the damage to buildings by debris flows based on extensive observed data of building damage and simulated debris flow intensity. A database of damaged buildings in the affected area of the Zhouqu debris flow was reconstructed. Numerical simulations using FLO-2D were conducted to determine the intensity of debris flows. A series of physical vulnerability empirical models for assessing the building damage has been proposed using various hazard intensity measures. Since buildings of different structural types have different resistances to debris flows, the vulnerability functions were developed for two typical types of structures, i.e. brick-concrete structures and reinforced concrete-frame structures. The proposed vulnerability functions are comparable with those for debris flows in Switzerland, Italy and Austria. The buildings may be completely destroyed when the debris flow depth is more than one half of the building height for both types of building structures.

Review Article: A comparison of flood and earthquake vulnerability assessment indicators

Abstract. In a cross-disciplinary study, we carried out an extensive literature review to increase understanding of vulnerability indicators used in the disciplines of earthquake- and flood vulnerability assessments. We provide insights into potential improvements in both fields by identifying and comparing quantitative vulnerability indicators grouped into physical and social categories. Next, a selection of index- and curve-based vulnerability models that use these indicators are described, comparing several characteristics such as temporal and spatial aspects. Earthquake vulnerability methods traditionally have a strong focus on object-based physical attributes used in vulnerability curve-based models, while flood vulnerability studies focus more on indicators applied to aggregated land-use classes in curve-based models. In assessing the differences and similarities between indicators used in earthquake and flood vulnerability models, we only include models that separately assess either of the two hazard types. Flood vulnerability studies could be improved using approaches from earthquake studies, such as developing object-based physical vulnerability curve assessments and incorporating time-of-the-day-based building occupation patterns. Likewise, earthquake assessments could learn from flood studies by refining their selection of social vulnerability indicators. Based on the lessons obtained in this study, we recommend future studies for exploring risk assessment methodologies across different hazard types.

The drought risk of maize in the farming–pastoral ecotone in Northern China based on physical vulnerability assessment

Abstract. Climate change is affecting every aspect of human activities, especially the agriculture. In China, extreme drought events caused by climate change have posed a great threat to food safety. In this work we aimed to study the drought risk of maize in the farming–pastoral ecotone in Northern China based on physical vulnerability assessment. The physical vulnerability curve was constructed from the relationship between drought hazard intensity index and yield loss rate. The risk assessment of agricultural drought was conducted from the drought hazard intensity index and physical vulnerability curve. The probability distribution of drought hazard intensity index decreased from south-west to north-east and increased from south-east to north-west along the rainfall isoline. The physical vulnerability curve had a reduction effect in three parts of the farming–pastoral ecotone in Northern China, which helped to reduce drought hazard vulnerability on spring maize. The risk of yield loss ratio calculated based on physical vulnerability curve was lower compared with the drought hazard intensity index, which suggested that the capacity of spring maize to resist and adapt to drought is increasing. In conclusion, the farming–pastoral ecotone in Northern China is greatly sensitive to climate change and has a high probability of severe drought hazard. Risk assessment of physical vulnerability can help better understand the physical vulnerability to agricultural drought and can also promote measurements to adapt to climate change.

토석류 수치해석을 통한 건물의 물리적 취약곡선 연구

토석류 수치해석을 통한 건물의 물리적 취약곡선 연구

The physical vulnerability of different types of building structure to debris flow events

Vulnerability assessment of elements at risk is a key component for risk assessment. The representative element at risk for debris flow is a residential building in downstream mountain, and the physical vulnerability of such a building depends on the structural characteristics of a building. The main objective of this paper was to construct physical vulnerability curves for different types of building structures in Korea to enable a quantitative assessment of debris flow risks. The physical characteristics of debris flows were analyzed based on 11 debris flow events that occurred in July and August, 2011. A total of 25 buildings that were damaged during these events were investigated in detail to determine the characteristics and patterns of damage. This study analyzes the relationship between the degree of building damage and the intensity of the debris flows through field survey data, spatial data, and empirical formula. Three different empirical vulnerability curves were obtained as functions of the debris flow depth, the flow velocity, and the impact pressure. Furthermore, the vulnerability function was characterized according to the structural type of the buildings. In the case of non-RC buildings, complete destruction occurred with an impact pressure greater than 30 kPa. For RC buildings, slight damage occurred with impact pressures less than 35 kPa. The impact pressure of debris flows corresponding to slight damage to RC buildings could result in complete destruction of non-RC buildings. The physical vulnerability curves suggested here have potential applications in quantitative assessment of the structural resistance of buildings to debris flow events.

토석류에 의한 건물의 물리적 취약함수 특성

2011년 7월과 8월 사이에 발생한 총 8개 토석류 재해 지역에 대한 재해이력 사례를 분석하여 각 재해지역의 토석류 물리적 특성을 파악하였다. 또한 각 재해지역에서 피해를 입은 15개 건물에 대한 손상 특성 분석을 수행하였다. 토석류의 물리적 특성과 건물 손상정도를 바탕으로 토석류의 높이, 속도 및 충격압력으로 구성된 취약함수를 구하였다. 또한 보강 콘크리트 구조와 비 콘크리트 구조와 같은 건물의 구조 형식에 따른 취약함수를 각각 산출하였다. 비 콘크리트 건물의 경우 토석류 충격압이 30 kpa 이상일 때 완전 파괴, 15~30 kPa일 때 심각한 손상, 0~15 kPa일 때 경미한 손상이 발생하는 것으로 분석되었다. 이에 비해 보강 콘크리트 건물의 경우 100 kPa 이상에서 심각한 손상, 35~100 kpa일 때 보통 손상, 0~35 kPa일 때 경미한 손상을 입는 것으로 파악되었다. 콘크리트 건물의 경미한 손상에 대응하는 토석류 충격압은 비 콘크리트 건물에서는 완전 파괴에 해당되는 손상을 가져다 줄 수 있음을 의미한다. 건물 구조형식과 토석류 물리적 특성에 따른 취약곡선을 비선형 회귀분석을 수행하여 함수형태로 나타내었다. 이러한 토석류 취약함수는 토석류 재해로 피해가 발생할 가능성이 있는 지역의 건물손상 정도를 정량적으로 평가하는 방법으로 이용할 수 있다. The physical characteristics of debris flows were analyzed from a total of 8 cases of debris flow disasters occurred in between July and August, 2011. 15 buildings damaged in these events were also investigated in detail to study the characteristics and patterns of building damages by debris flows. Physical vulnerability was obtained from the relationship of the degree of building damage and the physical characteristics of debris flow. Three different empirical vulnerability curves were obtained, which were functions of debris flow height, flow velocity and impact pressure, respectively. Furthermore, the vulnerability function was characterized according to the structural types of the building. In the case of non-concrete building, a complete destruction occurred at the impact pressure of more than 30 kPa, an extensive damage at the impact pressure between 15 and 30 kPa, a slight damage at the impact pressure below 15 kPa. In the case of reinforced-concrete buildings, an extensive damage occurred at the impact pressure of more than 100 kPa, a moderate damage at the impact pressure between 35 and 100 kPa, a slight damage at the impact pressure below 35 kPa. The impact pressure of debris flow corresponding to a slight damage to the reinforced-concrete building produced a complete damage for the case of non-concrete building, Nonlinear regression analysis was performed according to the physical characteristics of debris flow and the building structural type. The proposed physical vulnerability curves could be used as a quantitative assessment of the structural resistance of buildings affected by a debris flow event.

Assessment of physical vulnerability to agricultural drought in China

Food security has drawn great attention from both researchers and practitioners in recent years. Global warming and its resultant extreme drought events have become a great challenge to crop production and food price stability. This study aimed to establish a preliminary theoretical methodology and an operational approach for assessing the physical vulnerability of two wheat varieties (“Yongliang #4” and “Wenmai #6”) to agricultural drought using Environmental Policy Integrated Climate model (EPIC). Drought hazard index was set up based on output variables of the EPIC water stress (WS), including the magnitude and duration of WS during the crop-growing period. The physical vulnerability curves of two wheat varieties to drought were calculated by the simulated drought hazard indexes and loss ratios. And the curve’s effect on drought disaster risk was defined as A, B and C sections, respectively. Our analysis results showed that (a) physical vulnerability curves varied between two wheat varieties, which were determined by genetic parameters of crops; (b) compared with spring wheat “Yongliang 4#” winter wheat “Wenmai 6#” was less vulnerable to drought under the same drought hazard intensity scenario; (c) the wheat physical vulnerability curve to drought hazard displayed a S shape, suggesting a drought intensity–dependent magnifying or reducing effect of the physical vulnerability on drought disasters; (d) the reducing effect was mainly in the low-value area of vulnerability curve, whereas the magnifying effect was in the middle-value area, and the farming-pastoral zone and the Qinling Mountain–Huaihe River zone formed important spatial division belts.

The application of numerical debris flow modelling for the generation of physical vulnerability curves

Abstract. For a quantitative assessment of debris flow risk, it is essential to consider not only the hazardous process itself but also to perform an analysis of its consequences. This should include the estimation of the expected monetary losses as the product of the hazard with a given magnitude and the vulnerability of the elements exposed. A quantifiable integrated approach of both hazard and vulnerability is becoming a required practice in risk reduction management. This study aims at developing physical vulnerability curves for debris flows through the use of a dynamic run-out model. Dynamic run-out models for debris flows are able to calculate physical outputs (extension, depths, velocities, impact pressures) and to determine the zones where the elements at risk could suffer an impact. These results can then be applied to consequence analyses and risk calculations. On 13 July 2008, after more than two days of intense rainfall, several debris and mud flows were released in the central part of the Valtellina Valley (Lombardy Region, Northern Italy). One of the largest debris flows events occurred in a village called Selvetta. The debris flow event was reconstructed after extensive field work and interviews with local inhabitants and civil protection teams. The Selvetta event was modelled with the FLO-2D program, an Eulerian formulation with a finite differences numerical scheme that requires the specification of an input hydrograph. The internal stresses are isotropic and the basal shear stresses are calculated using a quadratic model. The behaviour and run-out of the flow was reconstructed. The significance of calculated values of the flow depth, velocity, and pressure were investigated in terms of the resulting damage to the affected buildings. The physical damage was quantified for each affected structure within the context of physical vulnerability, which was calculated as the ratio between the monetary loss and the reconstruction value. Three different empirical vulnerability curves were obtained, which are functions of debris flow depth, impact pressure, and kinematic viscosity, respectively. A quantitative approach to estimate the vulnerability of an exposed element to a debris flow which can be independent of the temporal occurrence of the hazard event is presented.

Assessment on Typical Drought Risk for Wheat Production in China Based on Natural Vulnerability

Food security is the base of human survival and national stability.,of which food supply-demand balance variation and its induced food price fluctuation are the two major concerns.Global food production has been kept on increase since 2000,though in a slow pace,which should be able to meet the basic diet requirement.According to the 4th IPCC report,however,from the end of 2007,the worldwide food supply problem has been paid great attention to due to a sky rocket of food price.The earth is getting warmer and the frequency of drought is increased. Consequently,the intensification of water stress to crops,resulted from both the long term climate change and increase of extreme weather events,may lead to the reduction of crop yield and the increase of drought disasters. To understand the mechanism of crop drought disaster process is the key to the understanding of food security and hence a possible solution to the problem.In the past researches,the concepts of physical vulnerability and social vulnerability are not always yet explicitly distinguished or separated regarding to agricultural drought disaster risk assessment,which restricts the understanding of process-based mechanism of disaster risk dramatically.The major focuses of studies on drought disaster risk assessment range from statistical analysis and probability analysis to prediction of drought hazard or disaster losses,whilst few attached importance to the quantitative separation of physical and social vulnerabilities. The goals of this paper are to explore and quantify the physical vulnerability and drought hazard and risk.The detailed process is as follows:Firstly,agricultural drought disaster risk assessment model is developed based on the physical vulnerability of crops.This model covers agricultural drought hazard possibility distribution estimation, physical vulnerability curve estimation,land use-based exposure assessment,coping capacity integration and risk assessment.Secondly,a case study on two typical wheat species in China is carried out,and a quantitative physical vulnerability to agricultural drought hazards is analyzed using a physical-process based crop growth model and Erosion Productivity Impact Calculator(EPIC).At the beginning,the one-dimension(point scale) crop growth model EPIC with a capability of depicting water stress and temperature stress is extended to a two-dimension(area scale) model,and the Spatial Erosion Productivity Impact Calculator(S-EPIC) can be used to simulate crop yield under different intensity scenarios of drought.Two extreme scenarios for crop growth and yield simulation were investigated. Finally,the maps of drought risk occurring every 2,5,10 and 20 years were charted separately based on the calculated probable distribution of drought hazard and the vulnerability curve.The results reveal that the wheat yield loss caused by drought is decreased from the northwestern part to the southeastern part of China.