URBAN FLOOD IMPACTS, FLOOD WATER QUALITY AND RISK MAPPING OF OLODO AREA, IBADAN, NIGERIA

This study assessed urban flood impact, flood water quality and vulnerability around Olodo area of Ibadan region, Nigeria. The study employed remote sensing and GIS techniques in creating vulnerability and risk maps. Digital terrain model (DTM) was used to get the topography of the study area. Footprints of buildings along the Egberi riverbank and flood plain in Olodo were created in the GIS environment from high resolution satellite imagery. Buffering operation was conducted to classify the buildings into risk zones based on closeness to the riverbank using ArcGIS 10.0. The study revealed that 326 buildings were within the very vulnerable and vulnerable zones because they were less than 15.2m away from the riverbank. The characteristics of water quality change during the flood and non-flood periods. TSS, DO, NOD, and COD were all higher during the flood event. Microbial analysis showed that water quality levels in the floodwater exceeded water quality standards (e.g., the coliform excess from 10 to 10,000 times), and thus this may be a health risk for local people during flood events. Concentration of Escherichia coli (E. coli) ranged from 484 to 1290 cfu/100 mL during flooding compared to 192 to 295 cfu/100 mL after flood. Salmonella was found to be high ranging from 659 to 1840 cfu/100 mL during flooding compared to 530 to 1034 cfu/100 mL after flooding.

Quantifying National-Scale Changes in Agricultural Land Exposure to Fluvial Flooding

This study quantifies the exposure of agricultural land in Aotearoa-New Zealand’s (A-NZ) flood hazard zones (FHZs). We developed a spatio-temporal flood exposure framework to quantify the extent of the area and yearly earnings before income and tax (EBIT) for arable, forestry, horticulture, sheep and beef, and dairy land in FHZs between 1990 and 2016. In 1990, ~1.57 million hectares of agricultural land were exposed, decreasing slightly to ~1.50 million hectares by 2016. However, there was a change in the lower-value types of agricultural land uses being exposed, such as for sheep and beef farming and forestry, toward dairy farming (from ~364,000 hectares in FHZs in 2008 to ~471,000 hectares in 2016). Dairy farming is more intensively staffed with larger amounts of fixed assets, making them less resilient to flood impacts. Despite this, conversion to dairy farming even within the identified FHZs has been driven by the increasing profitability of the enterprise. As a result of both the production value change and land area increases, the dairy EBIT values within FHZs rose rapidly from NZD 382 million to NZD 1.25 billion between 2008 and 2012, creating significantly more economic exposure for A-NZ. This trend is particularly evident in the Southland, Canterbury, and Waikato regions. Similarly, in the Marlborough, Tasman, and Hawke’s Bay regions, there was an increase in high-value horticultural land—predominantly viticulture—in FHZs (a increase of NZD 321 million in annual EBIT for exposed horticulture across the three regions). Identifying sub-national trends in agricultural flood exposure allows for a detailed analysis of the likely impacts in high-risk areas, which can inform emergency management plans and mitigative actions that diminish the economic impacts from flood events.

Mapping direct flood impacts from a 2020 extreme flood event in Central Vietnam using spatial analysis techniques

Purpose In October 2020, Vietnam was repeatedly hit by large storms, including Linfa, Nangka, Saudel and Molave, causing heavy rains and whirlwinds in the Central provinces of Vietnam. The heavy rain led to severe flooding in many localities. The water levels on major rivers broke records of historical flood events in 1950, 1979, 1999, 2007, 2010 and 2016. In response, this paper aims to quantify the impacts of 2020 flooding to support flood risk management activities and the relief agencies that can use the analysis. Design/methodology/approach This study demonstrates an approach to quickly map flood impacts on population, schools, health-care facilities, agriculture, transportation and business facilities and assess flood risks using available data and spatial analysis techniques. Findings The results show that all districts of Quang Binh were affected by the event, in which 1,014 residential areas, 70 schools, 13 health-care facilities, 32,558 ha of agriculture lands, 402 km road length, 29 km railway, 35 bridges on roads and 239 business facilities were exposed within flooded areas. Research limitations/implications This study is limited to direct or tangible impacts, including flooded residential areas, schools, health-care facilities, agriculture land categories, road networks and business facilities. Indirect or intangible impacts such as health, flood pollution and business disruption should be considered in further studies. Practical implications These detailed impact maps can support decision-makers and local authorities in implementing recovery activities, allocating relief and devoting human resources and developing flood risk management action plans and land-use planning in the future. Social implications This study investigates the context of flood impacts on population, schools, health-care facilities, agriculture, transportation and business facilities. Based on this research, decision-makers can better understand how to support affected communities and target the most at risk people with interventions. Originality/value This paper presents a framework to quantify the impacts of the 2020 extreme flood event using available data and spatial analysis techniques in support of flood risk management activities.

Community Flood Impacts and Infrastructure: Examining National Flood Impacts Using a High Precision Assessment Tool in the United States

Changing environmental conditions are driving worsening flood events, with consequences for counties, cities, towns, and local communities. To understand individual flood risk within this changing climate, local community resiliency and infrastructure impacts must also be considered. Past research has attempted to capture this but has faced several limitations. This study provides a nation-wide model of community flooding impacts within the United States currently and in 30 years through the use of high-resolution input data (parcel-level), multi-source flood hazard information (four major flood types), multi-return period hazard information (six return periods), operational threshold integration, and future-facing projections. Impacts are quantified here as the level of flooding relative to operational thresholds. This study finds that over the next 30 years, millions of additional properties will be impacted, as aspects of risk are expected to increase for residential properties by 10%, roads by 3%, commercial properties by 7%, critical infrastructure facilities by 6%, and social infrastructure facilities by 9%. Additionally, certain counties and cities persistently display impact patterns. A high-resolution model capturing aspects of flood risk as related to community infrastructure is important for an understanding of overall community risk.

Social Influences on Flood Preparedness and Mitigation Measures Adopted by People Living with Flood Risk

This paper aims to analyse evidence, based on one of the largest and most representative samples of households previously flooded or living with flood risk to date, of social patterns in a range of flood resilience traits relating to preparedness prior to a flood (e.g., property adaptations, contents insurance, etc.) and mitigations enacted during and immediately following a flood (e.g., receiving a warning, evacuation into temporary accommodation, etc.). The data were collected from a 2006 survey of 1223 households from a variety of locations across Scotland between one and twelve years after major local floods. Our analysis identifies remarkably few social differences in flood preparedness and mitigation measures, although some aspects of demography, housing and length of residence in an area, as well as personal flood history, are important. In light of this finding, we argue that social differences in vulnerability and resilience to flooding arise from deep-seated socio-economic and socio-spatial inequalities that affect exposure to flood risk and ability to recover from flood impacts. The engrained, but well-meaning, assumption in flood risk management that impoverished households and communities are lacking or deficient in flood preparedness or mitigation knowledge and capabilities is somewhat pejorative and misses fundamental, yet sometimes invisible, social stratifications play out in subtle but powerful ways to affect households’ and communities’ ability to avoid and recover from floods. We argue that general poverty and inequality alleviation measures, such as tax and welfare policy and urban and community regeneration schemes, are likely to be as, if not more, important in alleviating social inequalities in the long-term impacts of floods than social targeting of flood risk management policy.

Are interactions important in estimating flood damage to economic entities? The case of wine-making in France

Estimating flood damage, although crucial for assessing flood risk and for designing mitigation policies, continues to face numerous challenges, notably the assessment of indirect damage. It is widely accepted that damage other than direct damage can account for a significant proportion of total damage. Yet due to scarcer data sources and lack of knowledge on links within and between economic activities, indirect impacts have received less attention than direct impacts. Furthermore, attempts to grasp indirect damage through economic models have not gone below regional levels. Even though local communities can be devastated by flood events without this being reflected in regional accounts, few studies have been conducted from a microeconomic perspective at local level. What is more, the standard practices applied at this level of analysis tackle entities but ignore how they may be linked. This paper addresses these two challenges by building a novel agent-based model of a local agricultural production chain (a French cooperative wine-making system), utilized as a virtual laboratory for the ex ante estimation of flood impacts. We show how overlooking existing interactions between economic entities in production chains can result in either overestimation (double counting) or underestimation (wrong estimation of the consequences for the activity) of flood damage. Our results also reveal that considering interactions requires thorough characterization of their spatial configuration. Based on both the application of our method and the results obtained, we propose balanced recommendations for flood damage estimation at local level.

Flash flood impacts on the life and livelihood of women at haor areas in Bangladesh

Flash flood is a common disaster in northeastern haor areas of Bangladesh. It frequently affects the life and livelihood of haor people every year. Women are the most vulnerable in this catastrophic situation compared to men. The present study attempted to explore the effects of flash floods on women at Tahirpur Upazila in the Sunamganj district. A semi-structured questionnaire survey on 172 married women chosen from four villages, seven focus group interviews, and ten key informant interviews was conducted for primary data collection. A Flash Flood Impact Ranking (FFIR) was also prepared to grade the impacts on women based on a 3-points weighted severity scale. The study findings revealed that women suffered from different diseases with physical injuries and faced many difficulties managing the shelter, food, safe water, sanitation, and fuel for cooking during the flood. The FFIR displayed that crops damage, lack of funds, job opportunities, sanitation problems, and food insecurities were the top five disaster impacts on women. It is suggested that Government and other agencies should increase women's coping strategies by ensuring health services and employment opportunities to mitigate damage and flash flood-related problems.

Flood Impacts Analysis and Mitigation Approach towards Community Resiliency at Nageshwari Upazila, Kurigram

Nageshwari is an upazila of Kurigram locality of Bangladesh. It is one of the most vulnerable areas to flood disasters. Every year many devastating floods occurred in this area. One of the main purposes of the study is to identify flood hazards and their impacts on the people's perception of the study area. Another purpose is to recognize mitigation approaches (both scientific and indigenous practices). To complete the aim, semi-structured questionnaires are used. Besides some key informant interviews and focus groups, discussions are also used to validate the collected data. The key findings of the study are the larger impact of inundation on health, agriculture, fisheries, road and transport, water and hygiene, and housing. From the overall impacts in the study area, the most affected sector is agriculture and roads. From people’s perception, many problems are found due to devastating floods. Unemployment, food scarcity, communication problems, etc. are the common problems in the study area. People practice some indigenous knowledge to reduce the flood impacts. Scientific practices are also applied by the authority to mitigate the flood impacts. But these mitigation measures are not enough toward accomplishes the demand. Some appropriate measures must be needed to decrease the flood impacts. Early warning systems and information dissemination on floods are not well developed. Sufficient and frequent training is needed about proper flood management, early warning, and dissemination within the lessons area. People take some adaptation techniques to diminish the flood. The local Government also takes some initiatives to decrease the flood impacts. But proper flood management needs to be improved to decrease the flood impacts. Proper management and awareness-raising programs will reduce the impact of inundation to enhance the community resiliency of the area.

Lessons Learnt From Typhoons Fitow and In-Fa: Implications for Improving Urban Flood Resilience in Asian Coastal Cities

Frequent typhoons are significantly affecting the coastal cities via intensive rainstorms, tidal surges and strong wind. Natural factors such as climate change and global sea-level rise come alongside anthropogenic factors such as rapid urbanisation and land use/land cover change leading to detrimental consequences such as urban floods. This short communication offers various lessons learnt by Ningbo municipality from two strong typhoons that hit the city directly, namely “Fitow” in 2013 and “In-Fa” in 2021. On the one hand, the usage of “Big Data” and “Social Media” for bettering “Preparation” and “Prevention” reduced flood impacts significantly. On the other hand, the implementation of “Flood Insurance” speed up the “Recovery” processes. The successful “Preparation”, “Response” and “Recovery” helped Ningbo to enhance its flood resilience, and thus substantial impacts of injuries, household damages and associated economic loss were avoided. These three key terms should be heeded in typhoon/flood governance in which various stakeholders are involved with, and be incorporated into the city’s long-term strategic development plans to merge with the climate actions towards 2030s and beyond. This will be vitally important in reducing climatic hazards and improving coastal flood resilience under the future climatic uncertainties in Asian coastal cities. (196 words)