Regional Cooperation in Flood Management in the Ganges-Brahmaputra-Meghna Region: Bangladesh Perspective

Bangladesh is known to behighly vulnerable to floods. Frequent floods have put enormous constraints on its development potential. Unfortunately, the frequency of high intensity floods is on the rise. So far the country has struggled to put a sizeable infrastructure in place to prevent flooding in may parts of the country with limited success. In recent times, it was found that losses of lives and valuable assets could be significantly minimized by implementing non-structural measures including the improvement of flood forecasting and warning system. The existing flood forecasting and warning capacity of Bangladesh could be more effective if real-timedata could be acquired from upstreamareas within the Ganges-Brahmaputra-Meghna (GBM) catchment, where runoff is generated. In order to do so, Bangladesh needs to foster an effective regional cooperationwith the other GBM regional countries of India, Nepal, and Bhutan. This article examines how GBM regional cooperation could be useful towards managing floods in Bangladesh in particularand the region in general.     

Flooding in the Red River Basin – Lessons from Post Flood Activities

Flood of 1997 affected a large number of residents in the Red River Basin. Life disruption, economic damage, lengthy recovery process, physical and emotional trauma motivated a number of main initiatives to improve the level of preparedness in case of future floods. This review will focus on the involvement of the International Joint Commission (IJC). Personal experience is used in this review to emphasize a number of important lessons, of special relevance to Canadian portion of the basin, from the post flood activities. Level of preparedness for, and potential damage from future floods will benefit from focusing very serious effort on the improvement of the Canadian database, exchange of data with the U.S. and standardization of data collection, exchange and use. Tools for sustainable floodplain management are improving. However, the Red River Basin with its characteristics requires a special set of sophisticated tools that will enhance flood flow forecasting, planning of new flood control measures (structural and non-structural) and emergency operations of existing flood protection system. City of Winnipeg, being the largest population centre in the basin deserves a special attention. Additional protection of 670,000 people is required that will take into consideration temporal and spatial distribution of economic and social costs and benefits.     

Flood events, fatalities and damages in India from 1978 to 2006

High temporal and spatial variability of rainfall qualifies India to be highly vulnerable to floods. Recurring floods of various magnitudes play havoc with the lives and property of the people, leading to unplanned development and unchecked environmental degradation, thwarting and retarding the overall development of the country. Therefore, the purpose of the present study is to analyze the types and trends in terms of flood events, frequency, number of people killed, injured, missing and economic damage both in space and time on the basis of a nationwide database published by India Meteorological Department, Pune, from 1978 to 2006. Analysis of these long-term data has revealed that 2,443 flood events claimed about 44,991 lives with the average of 1,551 lives each year. In terms of population size, these figures translate into a loss of 1.5 human lives per million of the population. A majority (56 %) of flood fatalities were caused during severe flood events. However, the frequency of these events was just 19 % in comparison with heavy rainfall events (65 %). In spatial context, flood-related fatalities are distributed all over the country with highest fatalities in Uttar Pradesh (17 %), Maharashtra (13 %), and Bihar and Gujarat (10 % each). Most fatalities occurred during the summer season monsoon months of August (30 %) followed by July (29 %) and September (20 %). The country suffered a cumulative flood-related economic loss of about 16 billion US$ between 1978 and 2006 and a maximum economic loss of 1.6 billion US$ in the year 2000 alone. The study further suggests that both flood events and fatalities have increased in India over a period of time.     

The impact of climate change on coastal geological disasters in southeastern China

Climate change is presently a major global challenge. As the world??s largest developing country, China is particularly vulnerable to global warming, especially in the rapidly developing coastal regions in the southeast of the country. This paper provides an overview of the impacts of climate change on the nature of geological disasters in the coastal regions of southeastern China. In the context of climate change, processes with the potential for causing geological disasters in this region, including sea-level rise, land subsidence, storm surges, and slope failures, which already have a substantial occurrence history, are all aggravated. All these processes have their own characteristics and relevance to climate change. Sea-level rise together with land subsidence reduces the function of dikes and flood prevention infrastructure in the study areas and makes the region more vulnerable to typhoons, storm surges, floods, and astronomical tidal effects. Storm surges have caused great losses in the study areas and also have contributed to increases in rainstorms. As a result, numerous rainfall-induced slope failures, characterized by focused time concentration, high frequencies, strong ??burstiness,?? and substantial damage, occur in the study areas. To prevent and mitigate such disasters that are accelerated by climate change, and to reduce losses, a series of measures is proposed that may help to achieve sustainable development in coastal southeastern China.     

Flood hazard in Hunan province of China: an economic loss analysis

Natural and man-made disasters have been increasing and affecting millions of people throughout the world. Floods are the most common natural disasters affecting more people across the globe than all other natural or technological disasters and also are the most costly in terms of human hardship and economic loss. In order to explore the total economic loss, components of economic loss, and factors influencing economic loss during flooding, a retrospective study was carried out in year 2000 in areas that suffered floods in 1998 in Hunan province, China. A total of 10,722 families were investigated using a multistage sampling method. We found that the total economic loss to the 10,722 families investigated was US$ 8.925 million; translating into an average economic loss of US$ 832.45 per family and US$ 216.75 per person. Economic loss related to property loss, income loss, and increased medical cost accounted for 57.38%, 40.00%, and 2.62% of the total economic loss, respectively. Economic loss was significantly related to a family’s pre-flood income; duration of the flood; severity of flood; and type of flood. River floods yielded the highest economic loss and drainage problem floods yielded the lowest loss. We recommended that flood-related preventive measures should focus on the prevention of river floods and shortening the duration of floods with the view of significantly minimizing economic losses associated with floods.     

Hydrological hazards in Russia: origin,classification, changes and risk assessment

Hydrological extreme events pose an imminent risk to society and economics. In this paper, various aspects of hydrological hazards in Russia are analysed at different scales of risk assessment. It is shown that the number of hydrological and meteorological hazards in Russia has been growing every year. The frequency of economic losses associated with extreme low flow in this century has increased by factor five compared to the last decade of the previous century. With regard to floods, an interesting spatial patter can be observed. On the one hand, the number of floods in the Asian part of the country has increased, whereas on the other hand, the number and intensity of floods in estuarine areas in the European part of Russia have significantly reduced since the middle of the twentieth century, especially in the 2000s. This decrease can be attributed to runoff flooding in the mouths of regulated rivers, with an effective system of flood and ice jam protection. The analysis shows that there is an 8–12-year periodicity in the number of flood occurrences and that flood surges have intensified over the last 110 years, especially on the European territory of Russia. An integrated index that accounts for flood hazards and socio-economic vulnerability was calculated for each region of Russia. A classification of flood risk was also developed, taking into account more than 20 hydrological and social–economic characteristics. Based on these characteristics, hazard and vulnerability maps for entire Russia were generated which can be used for water management and the development of future water resources plans.

     

Hydraulic and flood-loss modeling of levee,floodplain, and river management strategies,Middle Mississippi River,USA

In this investigation, four scenarios were used to quantify the balance between the benefits of levees for flood protection and their potential to increase flood risk using Hazards U.S. Multi-Hazard flood-loss software and hydraulic modeling of the Middle Mississippi River (MMR). The goals of this study were (1) to quantify the flood exposure under different flood-control configurations and (2) to assess the relative contributions of various engineered structures and flood-loss strategies to potential flood losses. Removing all the flood-control structures along the MMR, without buyouts or other mitigation, reduced the average flood stages between 2.3 m (100-year flood) and 2.5 m (500-year), but increased the potential flood losses by $4.3–6.7 billion. Removing the agricultural levees downstream of St. Louis decreased the flood stages through the metro region by ~1.0 m for the 100- and 500-year events; flood losses, without buyouts or other mitigation, were increased by $4.3–6.7 billion. Removing the agricultural levees downstream of St. Louis decreased the flood stages through the metro region by ~1.0 m for the 100- and 500-year events; flood losses, without buyouts or other mitigation, were increased by 155 million for the 100-year flood, but were decreased by $109 million for the 500-year flood. Thus, agricultural levees along the MMR protect against small- to medium-size floods (up to the ~100-year flood level) but cause more damage than they prevent during large floods such as the 500-year flood. Buyout costs for the all the buildings within the 500-year floodplain downstream of urban flood-control structures near St. Louis are ~40% less than the cost of repairing the buildings damaged by the 500-year flood. This suggests large-scale buyouts could be the most cost-effective option for flood loss mitigation for properties currently protected by agricultural levees.     

Flood Management in India

In this paper, flood problems in India, regional variabilityof the problem, present status of the ongoing management measures, their effectiveness and futureneeds in flood management are covered. Flood problems in India are presented by four zonesof flooding, viz. (a) Brahmaputra River Basin, (b) Ganga River Basin, (c) North-WestRivers Basin, and (d) Central India and Deccan Rivers Basin. Some special problems,related to floods like dam break flow, and water logging in Tal areas, are also mentioned.Progress of various flood management measures, both structural and non-structural, arediscussed. In addition, future needs to achieve efficient and successful flood managementmeasures in India are also pointed out.     

Industrial accidents triggered by earthquakes,floods and lightning: lessons learned from a database analysis

Natural hazards and disasters can cause major accidents in chemical and process installations. These so-called Natech accidents can result in hazardous-materials releases due to damage to process and storage units, or pipes. In order to understand the dynamics of Natech events, accidents triggered by earthquakes, floods and lightning recorded in industrial accident databases were analysed. This allowed the identification of the most vulnerable equipment types, their modes of failure due to natural-event impact and the final accident scenarios. Moreover, lessons learned for future accident prevention and mitigation were derived. The analysis showed that pipes and storage tanks are the most vulnerable equipment for earthquakes, floods and lightning, calling for more research of equipment behaviour under natural-event loading. The damage modes and states are strongly dependent on the characteristics of the impacting natural event. Toxic dispersion, fires and explosions were observed as a consequence of all three types of analysed natural events. In the case of floods, two additional scenarios were identified. These are water contamination and the formation of toxic and/or flammable vapours upon reaction of the released chemicals with the floodwaters. The overall number of recorded Natech accidents was found to range from 2 to 5% of all reported accidents in the analysed databases.     

Spatially distributed rainfall information and its potential for regional landslide early warning systems

Hydrological extreme events pose an imminent risk to society and economics. In this paper, various aspects of hydrological hazards in Russia are analysed at different scales of risk assessment. It is shown that the number of hydrological and meteorological hazards in Russia has been growing every year. The frequency of economic losses associated with extreme low flow in this century has increased by factor five compared to the last decade of the previous century. With regard to floods, an interesting spatial patter can be observed. On the one hand, the number of floods in the Asian part of the country has increased, whereas on the other hand, the number and intensity of floods in estuarine areas in the European part of Russia have significantly reduced since the middle of the twentieth century, especially in the 2000s. This decrease can be attributed to runoff flooding in the mouths of regulated rivers, with an effective system of flood and ice jam protection. The analysis shows that there is an 8–12-year periodicity in the number of flood occurrences and that flood surges have intensified over the last 110 years, especially on the European territory of Russia. An integrated index that accounts for flood hazards and socio-economic vulnerability was calculated for each region of Russia. A classification of flood risk was also developed, taking into account more than 20 hydrological and social–economic characteristics. Based on these characteristics, hazard and vulnerability maps for entire Russia were generated which can be used for water management and the development of future water resources plans.     

Establishing the Database of Inundation Potential in Taiwan

The structural measure was the major solution for flood defense in Taiwan. However, the measure is always limited to the design standard and cannot prevent the damages when floods exceed certain scale. Therefore, non-structural measures for flood mitigation are the indispensable complements to structural solutions. The study introduces the establishment of inundation potential database that provides required information for the non-structural measures in Taiwan. The database was built by numerical simulations, based on different rainfall scenarios, and has been applied by the local governments of Taiwan for land use managements, flood warning systems, emergency responses, and flood insurance programs to reduce the flood damages and impacts.     

Geomorphological features of Northwestern Bangladesh and some problems on flood mitigation

The northwest region of Bangladesh is divided into four geomorphological units which show different flood features. The region has suffered severe flood damage both in 1987 and 1988. After these floods Bangladesh Action Plan for Flood Control was established by the World Bank. In the northwest region the plan proposed two major projects, namely, an interceptor drain and a diversion channel. A Polder Project is also going on in this region. However these major projects are mainly on structural methods and require much cost for long embankments. The author suggests smaller but reasonable projects combining structural and non-structural methods in the region.     

Analysis of flash flood disaster characteristics in China from 2011 to 2015

Flash floods are one of the most disastrous natural hazards and cause serious loss of life and economic damage every year. Flooding frequently affects many regions in China, including periodically catastrophic events. An extensive compilation of the available data has been conducted across various hydroclimatological regions to analyze the spatiotemporal characteristics of flash floods in China. This inventory includes over 782 documented events and is the first step toward establishing an atlas of extreme flash flood occurrences in China. This paper first presents the data compilation strategy, details of the database contents, and the typical examples of first-hand analysis results. The subsequent analysis indicates that the most extreme flash floods originate mainly from small catchments over complex terrains and results in dominantly small- and medium-sized flooding events in terms of scales; however, these events, abrupt and seasonally recurrent in nature, account for a large proportion of the overall flooding-related disasters, especially disproportionately affecting elderly and youth populations. Finally, this study also recommends several immediate measures could be implemented to mitigate high impacts of deadly flash floods, although it still requires long-term significant efforts to protect human life and property in a country like China.     

What is responsible for increasing flood risks? The case of Gangwon Province,Korea

We examined the anthropogenic and natural causes of flood risks in six representative cities in the Gangwon Province of Korea. Flood damage per capita is mostly explained by cumulative upper 5% summer precipitation amount and the year. The increasing flood damage is also associated with deforestation in upstream areas and intensive land use in lowlands. Human encroachment on floodplains made these urban communities more vulnerable to floods. Without changes in the current flood management systems of these cities, their vulnerability to flood risks will remain and may even increase under changing climate conditions.     

山丘平圩混合区小流域水文分析计算方法研究

洪水灾害常常给社会造成严重的经济损失,小流域洪水汇流速度快,易对下游造成瞬时毁灭性灾害,采取有效的小流域治理措施是必须的。根据山丘平圩区小流域特点分析比较设计洪水的计算方法,推荐采用瞬时单位线法,同时对小流域分片设计洪水组合进行了研究分析。以团结河流域上段治理为例进行具体分析,计算出该流域20年一遇防洪设计流量为472.60m3/s,为类似该地区的山丘、平原、圩区混合区设计洪水分析总结经验,提供参考,具有现实意义。     

Assessment of flood hazard,vulnerability and risk of mid-eastern Dhaka using DEM and 1D hydrodynamic model

Floods are regular feature in rapidly urbanizing Dhaka, the capital city of Bangladesh. It is observed that about 60% of the eastern Dhaka regularly goes under water every year in monsoon due to lack of flood protection. Experience gathered from past devastating floods shows that, besides structural approach, non-structural approach such as flood hazard map and risk map is effective tools for reducing flood damages. In this paper, assessment of flood hazard by developing a flood hazard map for mid-eastern Dhaka (37.16 km²) was carried out by 1D hydrodynamic simulation on the basis of digital elevation model (DEM) data from Shuttle Radar Topography Mission and the hydrologic field-observed data for 32 years (1972–2004). As the topography of the area has been considerably changed due to rapid land-filling by land developers which was observed in recent satellite image (DigitalGlobe image; Date of imagery: 7th March 2007), the acquired DEM data were modified to represent the current topography. The inundation simulation was conducted using hydrodynamic program HEC-RAS for flood of 100-year return period. The simulation has revealed that the maximum depth is 7.55 m at the southeastern part of that area and affected area is more than 50%. A flood hazard map was prepared according to the simulation result using the software ArcGIS. Finally, to assess the flood risk of that area, a risk map was prepared where risk was defined as the product of hazard (i.e., depth of inundation) and vulnerability (i.e., the exposure of people or assets to flood). These two maps should be helpful in raising awareness of inhabitants and in assigning priority for land development and for emergency preparedness including aid and relief operations in high-risk areas in the future.     

美国20世纪洪水损失分析及中美90年代比较研究

分析了美国20世纪洪水损失的演变情况及洪水损失对国民经济的影响,探讨了美国的洪水响应政策,并对中国和美国20世纪90年代的洪水损失进行比较研究.主要结论如下:①美国20世纪年均洪水损失以1.58%的增长率缓慢上升,20世纪末年均损失约为55.6亿美元;②洪水损失占GDP的比重逐渐下降,由20世纪30年代的0.334%下降到90年代的0.068%;③美国许多重大洪水政策的调整几乎都与特大洪水发生有关,呈由"遏制洪水"、"控制洪水"发展到"洪水管理"的演变历程;④通过比较研究发现,整个90年代是中国和美国洪水频发的时期,中国的年均洪水损失为1343.1亿元,损失占全国GDP的2.386%;而美国年均洪水损失虽然也达到了55.6亿美元,但只占全美GDP的0.068%;洪水对中国国民经济的影响远远大于对美国的影响.     

People at Risk of Flooding: Why Some Residents Take Precautionary Action While Others Do Not

Self-protective behavior by residents of flood-prone urban areas can reduce monetary flood damage by 80%, and reduce the need for public risk management. But, research on the determinants of private households’ prevention of damage by natural hazards is rare, especially in Germany. To answer the question of why some people take precautionary action while others do not, a socio-psychological model based on Protection Motivation Theory (PMT) is developed, explaining private precautionary damage prevention by residents’ perceptions of previous flood experience, risk of future floods, reliability of public flood protection, the efficacy and costs of self-protective behavior, their perceived ability to perform these actions, and non-protective responses like wishful thinking. The validity of the proposed model is explored by means of representative quantitative telephone surveys and regression analyses, and compared with a socio-economic model (including residents’ age, gender, income, school degree and being owner or tenant). Participants were 157 residents of flood-prone homes in Cologne, Germany, a city that has traditionally been subject to minor and major flood events. Results of the study show the explanatory power of the socio-psychological model, with important implications for public risk communication efforts. To motivate residents in flood-prone areas to take their share in damage prevention, it is essential to communicate not only the risk of flooding and its potential consequences, but also the possibility, effectiveness and cost of private precautionary measures.     

What do people think about the flood risk? An experience with the residents of Talcahuano city,Chile

In the province of Concepción (Chile), floods are considered one of the main natural hazards. One of the most important cities of this area is Talcahuano. During the last years, Talcahuano has been affected by a number of flood episodes, as a consequence of an increase in the frequency of extraordinary atmospheric events, along with a higher exposure to the flood risk caused by an intense urban development. On 27 February 2010, an 8.8° earthquake (Richter scale) occurred in central southern Chile and originated the tsunami which flooded a large percentage of the residential area and military base of the Talcahuano city. This flood event affected a population higher than 180,000 people (including 23 casualties and invaluable economic and environmental losses). The objective of this study is to investigate the social perception and knowledge of Talcahuano residents affected by different types of flood, including tsunami, emphasizing which are their risks, vulnerability, resilience and coping capacity concepts. In addition, the kind of measures that have been proposed to improve their capacity to face floods after having suffered the natural disaster will be determined. This social assessment has been carried out based on a survey to permanent residents. Research results reveal that their endogenous and exogenous characteristics have resulted determinant to explain their perception.