Development In Flood-prone Areas Research Articles

Advanced floodplain mapping: HEC-RAS and ArcGIS pro application on Swat River

AbstractFloods stand out as one of the most devastating environmental threats worldwide resulting in the tragic loss of human lives and significant damage to our essential infrastructure. This study focuses on creating floodplain maps for the two important reaches of Swat River in the Khyber Pakhtunkhwa Province of Pakistan, namely, Kalam–Khwazakhela and Khwazakhela–Chakdara reaches. The Advanced Land Observing Satellite Phased Array Type L-band Synthetic Aperture Radar (ALOS PALSAR) 12.5 m Digital Elevation Model (DEM) data has been used for this purpose. Furthermore, the sensitivity of the flood model was assessed for the Flood 2022 event, considering simulated flood depth, extent, and velocity in relation to various terrains derived from the 12.5-m ALOS PALSAR data. To estimate extreme flows for different return periods (2, 5, 10, 25, 50, and 100 years), the Log Normal (LN), Log Pearson III (LP3), and Generalized Extreme Value (GEV) distributions were employed for the frequency analysis. The GEV distribution turned out to be the best fit for modeling the Swat River for both the Chakdara and Khwazakhela gauge stations. To predict flood levels for the peak floods identified through frequency analysis and for the specific return periods the Hydrologic Engineering Center's River Analysis System (HEC-RAS) 2D simulations were performed. Subsequently the outcomes of this model were used to create floodplain maps using Geographic Information System Professional (ArcGIS Pro) software customized for various return periods. The analysis revealed a linear increase in flood inundation area with longer return periods. The floodplain maps developed hold significant importance for the governing authorities of the Swat region. These maps serve as essential tools for implementing proactive measures against potential infrastructure damage, thereby protecting against economic losses and enhancing public safety. This research effectively combines hydrological modeling and geospatial technology offering practical solutions for managing flood risks. It serves as a valuable guide for making well-informed decisions and promoting sustainable development in flood-prone areas.

Reevaluating the benefit of flood risk management for flood-prone livelihoods

As flood risk is projected to increase, effective flood risk management (FRM) is crucial not only for mitigating direct flood damage but also for contributing to the long-term improvement of livelihoods and hence the socioeconomic development of flood-prone areas in developing countries. While many studies have assessed avoided damage as the benefit of flood countermeasures, few recognize the impact on improvements in livelihood resulting from risk reduction. We present a novel framework that captures the dynamic relationship between decreasing flood risk perception and improvements in household livelihoods. Using the case of flood-prone Bago, Myanmar, we apply this framework to evaluate 127 flood management strategies under different assumptions of future climate change and socioeconomic features. We show that the benefits of improved livelihoods, when quantified alongside avoided flood losses, have a significant impact enough to change the cost-efficiency rankings of flood management strategies. The findings highlight the importance of incorporating livelihood improvements into FRM decision making to promote the sustainable development in flood-prone areas.

Navigating Climate Challenges: A Comprehensive Assessment of Climate Change Impact and Preparedness in Sunyani Municipal

This study intends to analyze climate change impact and readiness in the Sunyani Municipality, with an emphasis on land cover changes, climate mitigation activities, and disaster risk mapping. Land cover mapping using satellite photos from 1990 to 2020 shows a significant conversion of rural lands into agricultural and urban regions, with 62% of agricultural lands being repurposed for physical development. Climate change prevention initiatives by key organizations, such as NADMO and GNFS, are praiseworthy, but they confront problems such as limited resources. The Vulnerability Theory is used to identify the linked components that influence sensitivity to climate change impacts. Disaster risk mapping identifies flood-prone areas, putting 7,695 buildings and critical facilities at risk, underlining the importance of strong emergency response strategies. The report suggests improved spatial planning, regular reviews of development in flood-prone areas, and stakeholder collaboration to achieve full climate resilience. Finally, the findings emphasize the importance of proactive steps in moving Sunyani Municipality toward a more resilient and climate-ready future.

Cost-effective adaptation strategies to rising river flood risk in Europe

River flood risk in Europe could rise to unprecedented levels due to global warming and continued development in flood-prone areas. Here, we appraise the potential of four key adaptation strategies to reduce flood risk across Europe based on flood risk modelling and cost–benefit analysis. We find that reducing flood peaks using detention areas is economically the most attractive option. In a scenario without climate mitigation (3 °C global warming), they can lower projected flood losses in Europe by 2100 from €44(30–61) billion to €8.1(5.5–10.7) billion per year and lower population exposed by 84% (75–90%) or achieve a risk level comparable to today. The economic investment required over 2020–2100 would provide a return of €4(3.5–6.3) for each €1 invested. The risk reduction potential of strengthening of dykes is somewhat lower, at 70% (59–83%) for a comparable annual investment. Implementing building-based flood proofing and relocation measures is less cost-effective but can reduce impacts in localized areas.

Strategic land acquisition for efficient and equitable flood risk reduction in the United States

Land acquisition and subsequent prevention of future development in flood-prone areas offers high economic potential in reducing flood damage. However, there is an urgent need to evaluate the social outcome of this flood adaptation policy given the unequal exposure of vulnerable populations to flood impacts. Here, we use two additional evaluation criteria – equity of benefit distribution and population exposure reduction, along with economic benefit, to assess the social and economic outcomes of five land acquisition strategies in the United States. Under an assumed budget of US$1 billion, we found that land acquisition would generate an economic benefit of US$6.06 to $10.56 billion, ensure an equitable distribution of benefit, and remove 266,000 to 593,000 people from future flood risks. Compared to acquiring lands with high benefit-cost ratios, strategically acquiring lands in poorer and more populous areas would improve both social outcomes with only low to moderate reductions (13 %–43 %) in the economic efficiency. As global flood risk is projected to rise with disproportionate impact on the poor, our research highlights the social and economic capacities of strategic land acquisition for nationwide flood adaptation.

Performance of small reservoirs in Tulang Bawang Watershed for microhydro power plant

Recurring floods in the Tulang Bawang River have led to significant losses. In response, the government and local engineers have taken steps to manage flood events and harness excess water for electrical energy generation through the construction of five small reservoirs in the Tulang Bawang watershed. This study evaluates the performance of these reservoirs as micro-hydro power plants, with the aim of mitigating energy challenges in Lampung Province. To achieve this goal, we collected and analyzed hydrological data and calculated the potential electrical power output for each reservoir. By utilizing a 50- meter waterfall height, the sub-watersheds of Way Giham, Way Umpu, and Way Tahmi, with a combined water holding capacity of approximately 2 million cubic meters, are capable of generating around 3 MW of electrical power per reservoir. Similarly, Way Tuba and Way Basei sub-watersheds offer a potential of approximately 4 MW of electrical power per reservoir. Based on these calculations, it is evident that the small reservoirs in the Tulang Bawang watershed hold substantial potential for contributing to the electrical power supply, thereby addressing Lampung Province's energy challenges. These findings underscore the significance of utilizing available water resources to meet energy demands and promote sustainable development in flood-prone areas.

The Safe Development Paradox in Flood Risk Management: A Critical Review

Climate change and continued urban development in flood-prone areas exacerbate flood risks. Flood Risk Management authorities often turn to structural protection measures to minimise losses. However, these measures often lead to infrastructural lock-ins with potential unintended consequences as increased safety can induce increased development, ultimately leading to higher losses in the event of failures of the structural safe-guards in place. This process has been referred to as the Safe Development Paradox: a cross-cutting science-policy-practice challenge that requires a systematic understanding in the context of climate change and the United Nations Sustainable Development Goals. Yet, there are no comprehensive review studies, to date, that summarize the state of knowledge of the Safe Development Paradox. This paper provides the first evidence base through a critical review of the state-of-the-art and quantitative analysis of the peer-reviewed English-language literature since 2000, highlighting key knowledge gaps and issues hindering progress in addressing the Safe Development Paradox. It was identified that current research is compounded by a lack of consistent terminology, limited geographic distribution of case studies, and skewed emphasis on fluvial flooding. The review ends with potential directions across the science, policy, and practice domains for increasing knowledge and tackling the Safe Development Paradox.

Causes and Effects of Flooding in Nigeria: A Review

Flooding is an environmental hazard that needs appropriate measures to be instituted to stem the tide of occurrence. The study relied on previous academic/scholarly articles in achieving the aim. It was noted in the study that flooding is caused by natural and human activities. For instance, excessive rainfall, terrain and nature of soils are natural causes of flooding. Furthermore, poor environmental planning/monitoring, housing development in flood prone areas, deforestation, haphazard developments resulting in the blockage of drains, poor waste disposal practices, negligence by government in designing and implementing policies at various levels as well as poor environmental planning and weak enforcement of policies contribute to flood occurrence. To this end, the present study suggested that government should ensure that environmental management policies are properly enforced in the country. Equally, development control activities should be taken seriously to avoid erecting developments on flood plains and flood prone areas. Finally, regular environmental education should be given priority in the society.

Causes and Effects of Flooding in Nigeria: A Review

Flooding is an environmental hazard that needs appropriate measures to be instituted to stem the tide of occurrence. In recent times, flooding has become a regular feature hence, the study focused on examining the causes and effects of flooding in Nigeria. The study relied on previous academic/scholarly articles in achieving the aim. It was noted in the study that flooding is caused by natural and human activities. For instance, excessive rainfall, terrain and nature of soils are natural causes of flooding. Furthermore, poor environmental planning/monitoring, housing development in flood prone areas, deforestation, haphazard developments resulting in the blockage of drains, poor waste disposal practices, negligence by government in designing and implementing policies at various levels as well as poor environmental planning and weak enforcement of policies contribute to flood occurrence. As expected, the effects of flooding are negative. Notably, flooding results in submerging of farm lands, housing properties and loss the lives of victims. Due to the negative effects of flooding, it can be accepted that flooding is a serious environmental threat that demands the institutionalization of appropriate measures in ensuring its management. To this end, the present study suggested that government should ensure that environmental management policies are properly enforced in the country. Equally, development control activities should be taken seriously to avoid erecting developments on flood plains and flood prone areas. Finally, regular environmental education should be given priority in the society.

Building underwater: Effects of community-scale flood management on housing development

The Community Rating System (CRS) program was implemented by the U.S. Federal Emergency Management Agency (FEMA) in 1990 as an optional program to encourage communities to voluntarily engage in flood mitigation initiatives. This paper uses national census tract-level data from 1990 to 2010 to estimate whether CRS participation affects housing development patterns. Our results show that participating in the CRS is associated with reduced rates of new housing construction and mobile homes in flood-prone areas. When we separate flood mitigation activities under the CRS program into information-based and regulation-based activities, we find that regulatory approaches are more effective than informational approaches. These results show a general pattern, nationwide and across decades, of community-scale flood management efforts deterring housing development in flood-prone areas.

Nature-based solutions for managing rising flood risk and delivering multiple benefits

River floods are already the most damaging disaster type globally, with risk projected to rise in much of the world due to climate change, development in flood-prone areas, and/or deteriorating infrastructure. Nature-based solutions, such as using floodplains to manage floodwaters, can contribute to a diversified portfolio for managing flood risks. River floods are already the most damaging disaster type globally, with risk projected to rise in much of the world due to climate change, development in flood-prone areas, and/or deteriorating infrastructure. Nature-based solutions, such as using floodplains to manage floodwaters, can contribute to a diversified portfolio for managing flood risks.

Development, Responsibility, and the Creation of Urban Hazard Risk

Scholarly attention has recently shifted to the creation and redevelopment of urban hazardscapes. This body of work demonstrates how housing is deployed in close proximity to hazards, and how the attendant risks have been communicated—or not—to potential residents. Utilizing the case of Calgary, Alberta, this article uses interview data collected from flood-impacted residents, and looks at their perceptions of development and risk creation. The analyses focus on how people attribute responsibility for development in flood-prone areas, and their views on future development in these areas. Results reveal that many residents argued for more government regulations preventing new development in floodplains. Moreover, they viewed developers as narrow-interested capitalists who fail to protect public safety and work to conceal risk from the public. Others wished to see large structural mitigation projects—dams, levees, or floodwalls—or insisted that homebuyers be informed of flood risk prior to purchase. The article concludes by addressing the implications for scholarly work in urban sociology, environmental sociology, and the sociology of disaster—all of which grapple with tensions between place-making and risk creation.

High-resolution urban change modeling and flood exposure estimation at a national scale using open geospatial data: A case study of the Philippines

Many developing countries in Asia are experiencing rapid urban expansion in climate hazard prone areas. To support climate resilient urban planning efforts, here we present an approach for simulating future urban land-use changes and evaluating potential flood exposure at a high spatial resolution (30 m) and national scale. As a case study, we applied this model to the Philippines – a country frequently affected by extreme rainfall events. Urban land-use changes were simulated to the year 2050 using a trend-based logistic regression cellular automata model, considering three different scenarios of urban expansion (assuming low/medium/high population growth). Flood exposure assessment was then conducted by overlaying the land-use simulation results onto a global floodplain map. We found that approximately 6040–13,850 ha of urban land conversion is likely to be located in flood prone regions between 2019 and 2050 (depending on the scenario), affecting approximately 2.5–5.8 million additional urban residents. In locations with high rates of future urban development in flood prone areas (Mindanao Island, in particular), climate resilient land-use plans should be developed/enforced, and flood mitigation infrastructure protected (in the case of “nature-based” infrastructure) or constructed. The data selected for our land-use change modeling and flood exposure assessment were all openly and (near-)globally available, with the intention that our methodology can potentially be applied in other countries where rapid urban expansion is occurring. The 2050 urban land-use maps generated in this study are available for download at https://www.iges.or.jp/en/pub/ph-urban2050/en to allow for their use in future works.

How effective are drainage systems in mitigating flood losses?

The impacts of flooding can be devastating. Huge financial burden often follows major storm events to recover from structural damage. Well-designed drainage systems allow for effective discharge of stormwater, reducing property losses and expenditures on recovery. However, a lack of empirical studies on the topic has impeded the determination of which drainage method might be the most effective in preventing or minimizing property losses from flooding. This study assessed the economic impacts of three drainage systems − storage-, conveyance-, and infiltration-based facilities – on reducing flood damage recorded from 2009 to 2012 by Federal Emergency Management Agency in the Buffalo Bayou watershed in Houston, Texas, USA. Ordinary least squares and spatial autoregressive models were developed with a group of variables featuring drainage system, housing structure, geophysical environment, and storm characteristics. The results show that storage-based systems outperform conveyance-based mechanisms. Infiltration-based facilities are found to be less effective in reducing property damage because green spaces disconnected from sewer systems are rapidly inundated after being saturated while excessive overflow is not properly drained. This study confirms that the performance of a drainage system varies by facility type and environmental setting. The results encourage the recovery of wetlands and integration of retention/detention basins into community development in flood-prone areas to prevent potential future economic losses.

Making room for nature? Applying the Dutch Room for the River approach to flood risk management in Alberta, Canada

ABSTRACT Transferring the Dutch Room for the River (RftR) to other jurisdictions is not just about changes in technology. It also requires a fundamental shift in culture and governance, and hence is challenging to implement. Through a qualitative case study and applying a frame/framing analytical lens, we examine how the Dutch RftR was perceived and implemented in southern Alberta, Canada in three projects. Overall, Alberta interviewees perceived the RftR projects as triggering a paradigm shift from ‘fighting water’ to ‘living with water’ and as opening opportunities to expand this approach into future flood risk management projects across the province. But did this support translate into policies and practices? We explore the extent to which Alberta adopted four features of the RftR approach: (a) shifting away from mega-infrastructure, (b) making space for rivers, (c) moving people, and (d) regulating floodplain development. Also drawing on policy adoption models, we assess whether the RftR approach resulted in a significant shift towards more preventative, environmentally sustainable flood mitigation to reduce disaster risks and damages or whether a business-as-usual approach of undeterred development in flood-prone areas was undertaken with resulting reliance on disaster relief programmes.

Were the floods in the UK 2007 and Germany 2013 game-changers?

This paper examines recovery after major floods in the UK and Germany. It focuses on two areas that were badly hit by flooding: Catcliffe, near Sheffield in the UK, and Passau in Bavaria, Germany. It reports on surveys of residents and businesses in each place and on surveys of national flood experts in both countries. The two events were comparable in terms of impacts, levels of preparedness and government response and show similar patterns of speed and quality of recovery. In Germany, it took about 18 months for 90% or more of residents to get back to normal, while in the UK it took a year longer. This difference may be related to funding; in the UK, over 90% of funding came from household insurance while in Germany over 60% came from federal aid, which may have been quicker. In both countries, the economy had recovered to near normal within 12-18 months. The majority of people surveyed in both countries (74% in Germany and 67% in the UK) believe that their homes and businesses are as just as vulnerable now as they were before the respective floods. However, in the UK, half of the respondents thought their neighbourhood was safer and better prepared compared to only 11% in Germany. This may be because substantial progress has been made in improving protection in the UK in areas flooded in 2007. Both floods were considered to be 'game-changers' and resulted in a heightened awareness of flood risk, increased investment in flood defences and an increasing emphasis on citizens taking more responsibility for flood preparedness. However, the Environment Agency in the UK lacks powers to prevent development in flood-prone areas, in Germany there are issues of coordination across large catchments that cross state boundaries and the insurance sector could play a bigger role in 'building back better'. Many homes and businesses continue to be at risk from major floods and more progress needs to be made in making them more resilient. This article is part of the theme issue 'Urban flood resilience'.

Guiding developments in flood-prone areas: Challenges and opportunities in Dire Dawa city, Ethiopia.

One of the biggest challenges that developing countries are facing today is the management of development in flood-prone areas. Ethiopia is no exception, as it has suffered perennial floods in different parts of the country with devastating consequences. Floods in Dire Dawa are occurring more frequently than before and this is attributed to climate change, among other reasons. This study looks at guiding development in flood-prone areas in Dire Dawa. In this study, data were collected from selected kebeles (zones). Questionnaires, interviews and observation were used as data collection methods. Respondents were randomly selected from the communities for the administration of questionnaires. Analysis revealed that the return period of floods in Dire Dawa is getting shorter. The local authorities have come up with coping strategies, which are falling short of the expected outcome, with poor implementation being the major problem. The study concludes by recommending that the administration needs to identify and prioritise existing opportunities by implementing the already existing strategies. The city administration needs to establish a specific body for watershed management and flood protection responsible for carrying out research, early warnings, designs, pooling resources, implementing and managing interventions.

Flood protection ecosystem services in the coast of Puerto Rico: Associations between extreme weather, flood hazard mitigation and gastrointestinal illness

Floods are becoming increasingly influential in coastal cities due to the intensification of extreme weather events. The impacts of flooding go beyond damages to infrastructure, it also affects human health. During floods, discharge of sewage into streets increases exposure to pathogens causing gastrointestinal (GI) illnesses. A potential strategy for coastal protection during weather hazards is the use of flood protection ecosystem services, but their effectiveness at ameliorating the impact of floods on GI illnesses remain understudied. Here we explore the relationship between extreme rainfall, flood protection ecosystem services, and the occurrence of Medicare claims for gastrointestinal (GI) illnesses in Puerto Rico. We first conducted model averaging to detect variables explaining flood impact for the years (1999–2014), and then used these variables as predictors in a spatio-temporal analysis of GI illness in the same period (1999–2013). Our results show that flood impact varies proportionally with extreme rainfall, and inversely with flood protection ecosystem services, particularly due to the presence of karst soils. The protective effect of karst soils is lost when there is a high percentage of people living in flood prone areas, as suggested by a significant interaction effect between these two variables. In support of our hypotheses, cases of GI illness also spike after extreme rainfall events and are affected by the interaction effect of karst soils and people living in flood prone areas. Our results support the linkage between extreme weather events, flood damages and GI illnesses, and suggests a buffering role of ecosystem services that promote rainfall infiltration. The relevance of these ecosystem services, however, is affected by planning decisions such as residential development in flood prone areas. Our results help inform planning strategies for future weather hazards, accounting for the role of natural and built infrastructure on minimizing flood impacts and human health effects.

Coastal and river flood risk analyses for guiding economically optimal flood adaptation policies: a country-scale study for Mexico.

Many countries around the world face increasing impacts from flooding due to socio-economic development in flood-prone areas, which may be enhanced in intensity and frequency as a result of climate change. With increasing flood risk, it is becoming more important to be able to assess the costs and benefits of adaptation strategies. To guide the design of such strategies, policy makers need tools to prioritize where adaptation is needed and how much adaptation funds are required. In this country-scale study, we show how flood risk analyses can be used in cost-benefit analyses to prioritize investments in flood adaptation strategies in Mexico under future climate scenarios. Moreover, given the often limited availability of detailed local data for such analyses, we show how state-of-the-art global data and flood risk assessment models can be applied for a detailed assessment of optimal flood-protection strategies. Our results show that especially states along the Gulf of Mexico have considerable economic benefits from investments in adaptation that limit risks from both river and coastal floods, and that increased flood-protection standards are economically beneficial for many Mexican states. We discuss the sensitivity of our results to modelling uncertainties, the transferability of our modelling approach and policy implications.This article is part of the theme issue 'Advances in risk assessment for climate change adaptation policy'.

Drivers and Spatial extent of Urban Development in Flood-prone Areas in Metropolitan Lagos

Urban development in flood-prone areas has created many environmental challenges in many cities in Nigeria. This survey-based study examined the drivers and spatial extent of development in floodplains in metropolitan Lagos. A total of 1,031 (7.2%) buildings out of 14,273 were systematically selected along 211 streets out of 1,403 prone to flood, and a structured questionnaire was administered to heads of households to determine the factors influencing development in floodplains. A Thematic Mapper of 1990, Enhanced Thematic Mapper of 2000 and the Google Earth Landsat of 2014 were also analysed in ILWIS 3.3 Academic and Arc-GIs 10.2 to determine the extent of development in floodplains. The study revealed, in order of significance, closeness to place of work, nearness to market, closeness to children’s schools, low rent, low income, and family affinity as factors that influenced the development in floodplains in the Lagos metropolis. Ineffective control of development and inadequate compliance with planning and building regulations were additional factors. Urban development in flood-prone areas in Lagos increased from 9.3 km2 in 1990 to 10.50 km2 in 2000 and 17.80 km2 in 2014. The study recommends that floodplains should be acquired and effectively protected to prevent any form of physical development; they should serve as natural sink for storm water and urban green for passive recreation. Urban development regulations should be strictly enforced by the relevant government agencies, such as the Lagos State Building Control Agency in the Ministry of Physical Planning and Urban Development.