## 1 Introduction  
The Intergovernmental Panel on Climate Change (IPCC) reports have reported that a significant increase in greenhouse gas emissions is likely to be one of the main causes of climate change, as represented by global warming and it has accelerated frequent and intense disasters in many countries [1; 2; 3]. Natural disasters are one of the serious threats that can lead to the destruction or deterioration of social and economic development. With global warming, there has been a continuous rise in intense climate-related disasters mainly floods and storms worldwide [4]. Moreover, urbanization along with more precipitation has been increasing the risk of runoff and flooding in many parts of the world [4]. The Emergency Events Database (EM-DAT) data [5] over the past 20 years between 1998 and 2017 indicate that floods were the majority of all disasters type accounting for about 43% of all recorded events; they affected the largest number of people at more than two billion people; and storms were also the costliest type of disaster amounting to US$ 1300 billion in recorded damage. Such floods have been aimed at reducing the risk of damage and frequency through mainly various structural measures such as dams and river improvement works in many research and development projects on disaster mitigation plans. It has been however found that the structural flood mitigation alone has significant limitations in the reduction of flood damage caused by super typhoons and local torrential storms due to climate change [6]. In order to provide preemptive information on the process of prioritization and selection of flood mitigation alternatives, non-structural measures become a more essential tool rather than structural measures that are likely to even threaten the ecosystem [7; 8; 9]. The flood vulnerability assessment is one of the main components in the non-structural measures of flood mitigation especially to climate change [10], and one of the best-known definitions of the vulnerability to climate change is proposed in the IPCC Third Assessment Report (TAR) [1]. Based on the IPCC's conceptual framework for the vulnerability to climate change, many studies have conducted vulnerability assessments in various areas such as drought, heat wave, tidal wave, sea level rise, earthquake, biodiversity, fishery, etc. as well as floods [11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35]. The IPCC's framework consists of the three components such as exposure, sensitivity, and adaptability for the vulnerability assessment to climate change [1]. Note that adaptability is usually treated as a synonym for adaptive capacity [1]. According to some literature [11; 12; 13; 14; 15; 28; 29; 30; 31; 32; 33; 34; 35] sensitivity is expressed in other words as fragility or susceptibility, and adaptability is regarded as response capacity, coping capacity, or resilience with a slight difference in meaning between words. As multidimensional concepts are usually measured by a single composite indicator compiled from individual conflicting criteria [46], the vulnerability assessments to climate change have been commonly conducted by a composite indicator compiled from the constituent assessment components. Hence, several methods have been proposed to implement the mathematical and causal relations among the assessment components in measuring the vulnerability of a system to climate change. An approach for assessing the vulnerability was designed as a general equation form by integrating the IPCC's three primary assessment components independently contributing to the vulnerability as representatively suggested by [PERSON] [12]. As such, many flood vulnerability indicators have been derived from the three primary components with equal weights by multiplicative utility functions [13; 14; 15; 16; 17].