Climate change is leading to an increased frequency and intensity of extreme weather events, like floods ^[1][2][1,2]. The occurrence of such phenomena poses significant hazards to both human life and property. As a result, these catastrophes tend to inflict greater harm on households, communities, and nations, primarily due to factors such as uneven distribution of hazards, exposure, and vulnerability [3]. Worldwide, climate change is contributing to a rise in flood occurrences and intensity [4]. Warming temperatures are responsible for more extreme weather phenomena, such as intense rainfall and snowfall, leading to flooding ^[5][6][5,6]. Additionally, rising sea levels caused by melting glaciers and ice are exacerbating coastal flooding ^[6][7][8][6,7,8]. Deforestation contributes to climate change by releasing stored carbon, intensifying greenhouse gases and global warming. This alteration in climate patterns increases the likelihood of heavy rainfall and floods. Moreover, deforested regions are more susceptible to flooding due to the diminished vegetation’s capacity to absorb water and stabilize soil ^[9][10][11][9,10,11]. The global population residing in urban areas is continuously expanding [12], leading to urban sprawl and soil sealing [13]. The interplay of extreme weather and climate change impacts rainfall patterns in water catchment regions [14], consequently leading to higher flow rates and faster runoff generation ^[14][15][14,15]. The combination of urbanization growth and expected climate shifts will lead to heightened extreme weather events, resulting in more frequent and severe urban flooding occurrences. These inundations may arise from either river floods or rainfall-related floods (pluvial floods). Furthermore, there is a global trend of an increasing elderly population residing in urban areas [16].

The term “flood” refers to the “transient inundation of land that is conventionally non-submerged” [14]. Though alterations in precipitation within a drainage basin are the predominant catalyst for river flooding ^{[9][17][18][19]}[9,17,18,19], other factors, such as swift snow thaw in mountainous regions ^[20][21][20,21] and dam malfunctions, may also contribute to this phenomenon ^[22][23][22,23]. Storm surges [24] and tsunamis [24] are two coastal phenomena that may lead to inundation. Flooding resulting from river and coastal events is typically an outcome of natural occurrences, and the severity and frequency of such events are connected to specific areas. The sheer force of water [25] associated with these events may often result in significant damage. Moreover, in addition to the physical harm inflicted by water, its force can act as a powerful agent of erosion [26]. This can lead to the degradation of materials situated beneath the foundations of buildings, ultimately resulting in their collapse [26]. Subsequent to the recession of a flood, the aftermath may exacerbate owing to several factors, such as power and water shortages, coupled with the dissemination of ailments such as cholera, leptospirosis, and typhoid fever ^[27][28][27,28], These circumstances can lead to additional economic and personal losses in the affected region [29]. Although these floods result from natural factors, the majority of the damage is attributed to human habitation in flood-prone regions ^[30][31][32][30,31,32]. People often reside in these areas due to the limited availability of alternative locations for construction within a municipality. The presence of modern engineering infrastructure can create a false sense of security, as it does not entirely eliminate the risk of flooding [33]. Consequently, recent shifts in land use are primarily driven by population growth and economic development in flood-prone regions, rendering societies more vulnerable to such occurrences ^[34][35][34,35]. Hence, rainfall plays a vital role in assessing climate change, particularly concerning floods. To classify a flood event, essential elements like flood severity, duration, and inundation area are examined [36]. These factors act as key indicators for understanding and characterizing floods. Utilizing quantitative assessments of flood risks and models is crucial in making informed decisions to prevent disastrous flood incidents [37].

2. Indicators Used to Measure Social Vulnerability in a Flood

The indicators of social vulnerability to floods were most frequently related to demographic characteristics, particularly in the stages of disaster response and recovery. The indicators most frequently detected after these were those related to socioeconomic status, primarily noted during the response phase. The correlation between demographic as well as socioeconomic factors and their impact on susceptibility to inundations highlights the significance of characteristics like ethnicity, gender, age, and income in determining a society’s resilience, response, and recovery from flood-related disruptions. In addition, other significant factors include health, education, risk perception, migration, disability, and disabled persons. Floods can significantly impact both the physical and psychological health of individuals and communities ^[38][58]. Additionally, exposure to contaminated floodwaters can lead to waterborne diseases, posing a severe health risk, while disrupted access to medical assistance during floods can delay treatment for injuries and medical conditions, amplifying health concerns ^[10][39][10,59]. Moreover, the psychological toll of the upheaval caused by floods, including displacement and loss, can lead to heightened stress and emotional distress. Addressing the health impact of floods requires proactive disaster preparedness and response measures, such as early warning systems, evacuation plans, and improved infrastructure. Public awareness and education on flood risks and safety measures are essential to empower individuals and communities to protect themselves during such events ^[38][40][58,60]. By understanding and effectively responding to the health consequences of floods, communities can enhance their resilience and safeguard their well-being in the face of these challenging natural disasters. Meanwhile, education plays a significant role in shaping how individuals comprehend and react to flood-related information as well as resources ^[41][42][61,62]. Education in this context pertains to the level of formal schooling and knowledge acquired by individuals. People with higher levels of education are more likely to comprehend flood warnings issued by authorities, enabling them to take appropriate and timely actions during flood events ^[43][63]. They can also access recovery resources more effectively, utilizing problem-solving skills and resource management capabilities ^[44][64]. On the other hand, individuals with limited formal education may face challenges in comprehending flood warnings and finding recovery resources, potentially making them more vulnerable to the impacts of floods ^[45][46][50,65]. Enhancing education and promoting flood-related awareness can improve preparedness and response among communities, reducing the adverse consequences of floods on vulnerable populations. Moreover, risk perception refers to how individuals and communities perceive the likelihood and severity of potential hazards, such as floods ^[47][66]. It involves people’s subjective judgments and beliefs about the risks that they face, which can be influenced by various factors, including past experiences, cultural beliefs, and access to information ^[48][49][67,68]. Individuals with high risk perception are more likely to take precautionary measures and engage in preparedness actions to reduce their vulnerability to floods ^[10][50][10,69]. They are more likely to pay attention to warnings, plan for evacuation, and implement strategies to safeguard themselves and their properties during flood events. Understanding risk perception is crucial for disaster management and community resilience, as it can help authorities tailor communication strategies, improve preparedness programs, and foster a better understanding of how individuals respond to flood risks ^[51][70]. On the other hand, migration refers to the movement of people from one location to another, often driven by various factors like economic opportunities, environmental changes, or seeking better living conditions. In the context of flood vulnerability, migration can have both positive and negative impacts [21]. People may migrate away from flood-prone areas to avoid the risks associated with floods, reducing their vulnerability. However, migration can also lead to increased vulnerability if people relocate to areas with a higher flood risk or inadequate infrastructure, or if they become displaced during extreme flood events [21]. The term “disability” denotes physical or mental impairments that hinder an individual’s daily functioning, and this can be further exacerbated by flood events. Disabled persons are individuals with disabilities who may encounter additional difficulties in terms of preparing for and responding to flood events. Overall, these factors highlight the complex and multifaceted nature of social vulnerability to floods, as well as the need for a comprehensive understanding of the drivers and impacts of vulnerability in order to effectively address and mitigate flood risks.

3. Demographic Characteristics

In contemporary research, demographic characteristics serve as frequent indicators of social vulnerability. Nevertheless, there is often an inconsistency in the academic literature in terms of the exact effect of individual demographic variables on socially vulnerable populations. For example, there are studies that highlight that children are a particularly susceptible demographic in the population; however, they may also act as a driving force for promoting resilience by means of fostering community networks through their education or aiding in household recovery endeavors ^[34][52][53][34,72,73]. It is commonly assumed that the elderly and women are the most vulnerable; however, research on fatalities related to floods reveals that young ^[54][49] and middle-aged men are also at risk due to their inclination towards risky behavior ^[55][52], rescue activities, and health impairments caused by drug or alcohol consumption ^[4][54][4,49]. In the literature, age is widely recognized as the primary demographic factor that influences social vulnerability, mainly due to its pervasive prevalence and consequential impact. The age variable includes the ratio of inhabitants classified into four age groups: those aged 65 and above; aged 4 and below; individuals aged 5–14; and residents aged 15–19 ^{[4][25][26][27][28][29][30][31][32][33][45]}[4,25,26,27,28,29,30,31,32,33,50]. From these findings, a negative outcome has been shown for elderly people, indicating an increased susceptibility to vulnerability. Reducing social vulnerability with regard to age can be accomplished by utilizing prior experience with disasters and taking proactive measures in the mitigation phase; however, studies suggest that the elderly and young are more susceptible to disasters due to their dependence and physical condition, with limited linear connections between age and vulnerability identified. ^[4][54][56][4,49,51]. This indicates that individuals who fall into the categories of “very young” or “very old” may require additional assistance and support during disasters due to their age-related limitations. Disabled populations, including those living in institutions, those with limited abilities to care for themselves, individuals with long-term or chronic illnesses requiring continuous care, and residents of nursing homes, have frequently been identified as the main driver of social vulnerability. According to research, patients in nursing homes and hospitals face significant challenges when it comes to evacuation and seeking shelter in situ ^[56][57][51,54]. Furthermore, in severe situations, family members of patients may hinder the evacuation of those who require self-care. The presence of limited mobility, dependence on care, and reliance on medication as well as other services poses significant challenges to the process of evacuation. In contrast, when services are disrupted, the recovery process may be impeded due to the increasing difficulty in providing care for special needs populations ^[57][54]. Furthermore, recognizing the complex relationship between gender identity and flood susceptibility is essential, as women are disproportionately responsible for taking care of their families ^[58][44]. Gender-based vulnerability was evident in both developed and developing nations, stemming from differences in resource accessibility, opportunities, power, rights, informal sector employment, and income [26]. The only choice available to women is often informal sectors with low wages, which leads to limited opportunities for economic expansion and lower pay than men [27]. The impact of gender on susceptibility to floods is not a simple phenomenon to understand; women are recognized for their superior coping mechanisms, greater commitment to obtaining knowledge related to risk, and stronger social bonds, which account for this [33]. The analysis of individual cases has demonstrated the difficulty in generalizing the vulnerability of women in society. Furthermore, it is important to consider the overall complexity and diversity of individual cases when analyzing the vulnerability of women in society. Even in developing nations with high levels of inequality, social vulnerability cannot be predicted solely by gender. Women’s daily living conditions are affected by their socioeconomic status, household structures, and geographic locations, making it an unreliable indicator [4]. The evidence from several studies conducted in this specific context suggests that gender is not a determining factor in the level of social vulnerability experienced during flooding events ^[59][60][55,57]. The factors of race, class, ethnicity, and immigration status serve as supplementary drivers of social vulnerability to floods. Cultural and linguistic obstacles can impact the selection of residential areas in high-risk zones, pre-disaster mitigation measures, and the availability of post-disaster resources for recovery ^[52][53][61][72,73,74].

4. Socioeconomic Status

The elements that determine socioeconomic status are commonly utilized as primary features in measuring social vulnerability in different geographic locations. In social vulnerability studies, several common indicators of socioeconomic status are measured, such as household composition, poverty, profession, academic background, economic and employment status, and property ownership. At the individual level, social vulnerability may arise from a variety of factors, including resource constraints, power dynamics, poverty, and marginalization. These factors can limit access to resources, influence coping behaviors, and induce stress [8]. Similarly, at the community level, social vulnerability is determined by factors such as income distribution, resource accessibility, and economic asset variety ^[62][46]. Within this specific context, income and poverty are the foremost factors that significantly impact social vulnerability. The primary reason for this is that income is intricately connected with other forms of capital that could potentially act as alternative indicators for social vulnerability to floods. To assess social vulnerability to floods, various indicators can be used, such as access to education, affluence, occupational category, overcrowding in residences, home or car ownership, and unemployment [19]. Education is an important factor in the correlation between income and other forms of capital. Individuals who are educated have a greater advantage in all areas of life compared to those who have not received education or have only received minimal education. Moreover, it can lead to better-paying jobs and ultimately result in higher incomes [31]. As a result, this may lead to an increase in asset ownership, though at a higher cost for wealthier households specifically in regard to flood damage; however, flood damage expenses make up a smaller fraction of the total income and capital of wealthier households [32]. On the contrary, a lower level of education is correlated with poverty, unemployment, overcrowding, marginalization, and income inequality. Low-income groups tend to experience more severe negative effects from detrimental flood incidents, and recovering from a moderately damaging event may take years for individuals who lack adequate financial resources, as indicated by [27]. Moreover, individuals with a higher level of education are less likely to be vulnerable to any form of hazard. According to [19], someone who has sufficient education and knowledge about a certain issue will have a more thorough understanding of the nature of a hazard and its potential effects on them.

5. Health

Health is a primary indicator of social vulnerability to flooding. Furthermore, flooding causes adverse consequences on fatality rates and bodily as well as psychological health. In particular, the most significant impact of floods on human health is the fatalities resulting from drowning. Thus, variables such as medical services, health issues, and proximity to healthcare facilities are crucial components in evaluating social vulnerability ^{[4][54][56][57]}[4,49,51,54]. Deaths resulting from flood-related illness can be influenced by various factors, such as age, gender, medication disruptions, and public water consumption ^[54][49]. Meanwhile, the impact of flooding on psychological well-being may vary depending on individual factors, such as anxiety and stress levels, age, gender, pre-existing health conditions, and recovery duration [4]. Additionally, floods can also have a significant impact on mental health, which can be prolonged due to conflicts with insurance companies and homeowners, as well as the disruption of various public, commercial, and health services ^[4][30][4,30]. Despite establishing the key determinants of vulnerability to health issues caused by floods, current research does not come to a consensus on the demographic and societal aspects linked to health outcomes from floods. In addition, the influence of flood circumstances in worsening health concerns and mortality is still inconclusive.

6. Coping Capacity

Analyses of social vulnerability often focus on identifying social characteristics that increase susceptibility to negative impacts; however, it is important to recognize that social vulnerability also includes individuals’ ability to manage the impacts of hazards in the short term and adapt to them in the long term ^[63][64][75,76]. Coping capacity refers to the capacity of individuals and communities to effectively manage the adverse effects of hazards, especially natural disasters like floods. Coping strategies are successful when they allow individuals to access or allocate resources to meet immediate needs without putting assets and income sources at risk. These resources can be both individual, such as personal skills and knowledge, and social, such as support networks and community organizations. Successful coping strategies involve accessing or allocating these resources in a way that allows people to overcome immediate challenges while also maintaining their long-term assets and livelihoods. This means that people need to be able to balance their short-term needs with their long-term goals. The concept of coping capacity is important because it helps us understand why some individuals and communities are better able to recover from disasters or crises than others. The specific strategies adopted vary depending on social, physical, and geographic contexts. In the literature, the evaluation of coping capacity involves examining not only proactive measures taken before flooding, such as preventive and adaptive actions, but also reactive strategies implemented immediately after an event ^[65][77]. This means that coping capacity can be understood as both proactive measures taken before a disaster occurs and reactive measures taken in response to a disaster. Coping capacity refers to the ability of individuals and communities to deal with and recover from the impacts of disasters. Preventative measures are actions taken before a disaster occurs to reduce the impact of a disaster. In the case of floods, preventative measures include accumulating food and medicine supplies, saving finances, arranging construction materials, and obtaining insurance coverage ^[66][67][78,79]. These measures can help individuals and communities prepare for a flood and reduce the damage caused by a flood; however, the use of preventative strategies is constrained by income and land tenure. This means that individuals and communities with limited financial resources or insecure land tenure may not be able to take these preventative measures. Instead, the majority of pre-flood actions focus on elevating structures and their contents in order to protect residences from flooding. Structural mitigation refers to physical changes made to buildings to reduce the impact of a disaster. In the case of floods, this may involve elevating the building or its contents to prevent damage from floodwaters ^[68][80]. While these structural mitigation measures can be moderately effective in reducing damage, they may not be accessible to all individuals and communities. This highlights the importance of addressing social and economic inequalities in disaster risk reduction efforts.

7. Risk Perception

The evaluation of risk perception centers on comprehending the manner in which perception influences conduct and mitigates susceptibility. In the context of flood-related calamities, numerous case studies have frequently noted the influence of risk perception on societal vulnerability. Previous research endeavors have delved into diverse aspects of flood perception, encompassing flood awareness, antecedent experiences, trust, appraisal of flood risk, as well as demographic characteristics [25]; however, the findings regarding perception and vulnerability were often contradictory in nature. The issue of flood awareness and knowledge has frequently been the subject of investigation, with the underlying belief that awareness serves as a crucial prerequisite for preparedness ^[69][81]. Emotions such as fear, uncertainty, and concern are important intermediaries in the relationship between cognizance and safeguarding measures ^[64][70][76,82]. Indeed, several studies have reported a correlation between a lack of awareness regarding floods and a limited uptake of measures aimed at flood protection and preparedness ^[46][71][65,83]. Generally, measures are implemented by considering elevating homes, acquiring flood insurance, accumulating supplies, relocating building contents to higher floors, and carrying out evacuations. Although government dissemination of official flood information can increase awareness, it may not be enough to reduce societal susceptibility.

8. Land Tenure Property

Social vulnerabilities across land tenure categories differ during a disaster, indicating that individuals belonging to a specific tenure category may be vulnerable in one phase of a disaster but not in another. Before a flood occurs, homeowners tend to become more aware of flood hazards ^[72][84], understand alerts better [25], and quickly take steps to prevent damage ^[73][85], and are less likely to seek emergency shelter ^[74][86]. Meanwhile, flood insurance was mainly considered a factor for reducing the impact of floods in studies conducted in developed countries ^[57][54]. Nevertheless, the connection between tenure and flood insurance is not straightforward. In the aftermath of the flooding, tenants experienced a greater number of health-related consequences and stress compared to property owners during the flood event [8]. Furthermore, they continued to rely on property owners during the recovery and reconstruction processes. In response to flooding, property owners were also more inclined to engage in structural enhancements to mitigate future flood-related losses [27]. There are multiple factors that contribute to the stronger attachment that homeowners tend to have to their homes compared to renters. These factors include emotional attachment, market conditions, and control over maintenance and repairs.

9. Disaster Management Plans

Disaster management plans are designed to address the unique challenges posed by different types of disasters ^[51][70]. Each disaster requires a tailored approach for an effective mitigation and response. Accordingly, higher-risk areas receive greater attention and allocation of state resources to ensure comprehensive protection ^[62][75][46,87]. In the context of flood management, the flood vulnerability matrix serves as a valuable tool to guide suitable actions. These actions may involve the maintenance of existing reservoirs and the construction of new water storage dams, ranging from small- to large-scale structures ^[51][70]. These reservoirs play a crucial role in regulating water flow, especially during flood events. By strategically managing water release, downstream areas can be safeguarded from excessive flooding. To further mitigate flood risks, it is essential to adopt measures that reduce runoff and divert floodwaters into designated reservoirs [36]. These reservoirs should be strategically located at a safe distance from populated regions to minimize potential damage and protect human lives ^[73][85]. Special attention should also be given to city drainage systems, ensuring the efficient channeling of excess water away from urban areas ^[76][88]. A proactive approach involves diverting runoff water to potential flood pocket zones, which can act as natural storage areas, helping protect cities and communities from the brunt of flood impacts. By employing a combination of infrastructure development, strategic planning, and proper drainage management, disaster management plans can enhance flood resilience and minimize the devastating consequences of flooding events on vulnerable populations ^[71][83].