Flood vulnerability assessment of donstream area in Mono basin in Yoto district, south-eastern Togo
par Abravi Essenam KISSI
University of Lome - Master 2014
The concepts of hazard, disaster and vulnerability have been extensively used in various disciplines with different meanings. Even for natural hazards, such as floods, no unique definitions and assessment procedures have been widely accepted (Pistrika and Tsakiris, 2007, p 1). Hazard is the probability of occurrence within a specified period of time and within a given area of a potentially damaging phenomenon (Maiti, 2007, p 10). This definition adds both spatial and temporal components to the definition of hazards while another definition from UNISDR (2009, p 17) refers hazard to "a dangerous phenomenon, substance, human activity or condition that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage." Hazard is, in the case of river-floods, a natural event that is perceived as a threat and not as a resource by humans (Fekete, 2010, p 31). For the author, hazard is revealed in the state of exposure, when the natural event actually hits the vulnerable elements. In technical settings, hazards are described quantitatively by the likely frequency of occurrence of different intensities for different areas, as determined from historical data or scientific analysis.
Hazard becomes a disaster when it hits a vulnerable community. It causes disaster when large numbers of people are killed, injured or affected in some ways (Maiti, 2007, p 10). In the same line of thought FAO (2008, p 16) points out that disasters of all kinds happen when hazards seriously affect communities and destroy temporarily or for many years the livelihood security of their members. Another definition from ISDR refers disaster to «a serious disruption of the functioning of a community or a society causing widespread human, material, economic or environmental losses which exceed the ability of the affected community or society to cope using its own resources". A disaster results then from the combination of exposure to a hazard, socio-ecological vulnerability that are present, and the limited capacities of households or communities to reduce or cope with the potential negative impacts of the hazard.
Assessing and measuring vulnerability in the context of natural hazards and climate change requires first and foremost a clear understanding of the concept (s) of vulnerability (Birkmann, 2013, p 9 ). Vulnerability is an important concept in human environment research, its conceptualization has been interpreted in many different ways, according to the perception of the researchers. The word "vulnerability" has created important links between different research communities, particularly disaster risk management (DRM), climate change adaptation (CCA), development and resilience research (Birkmann ,2013, p 9).
Cannon (1990) refers vulnerability only to biophysical exposure, where vulnerability is described as a measure of the degree and type of exposure to risk generated by different societies in relation to hazards.
Some studies found that vulnerability only refers to the susceptibility of a given system; United Nation/ISDR (2004) and the United Nation Development Programme (UNDP, 2004) view vulnerability as a human condition or process resulting from physical, social, economic and environmental factors, which increase the susceptibility of a system to be damaged from impact of a given hazard.
Other authors, like Blaikie et al.(1994) and Wisner, et al. (2004) relate vulnerability of a system or a community only to its capacity to anticipate, cope with, resist and recover from the impact of a hazard.
Adger (1999) views vulnerability as a function of two components: the effect that an event may have on humans, referred to as social vulnerability and the risk that such an event may occur, often referred to as exposure.
According to Chamber (1983), vulnerability has two sides: an external side of risks, shocks to which an individual or household is subjected to climate change and an internal side, which is defencelessness, meaning a lack of means to cope without damaging loss.
Numerous studies define vulnerability as being a function of exposure, susceptibility or sensitivity, coping capacity or resilience. Watson et al. (1996), defines vulnerability as the extent to which climate change may damage or harm a system, depending not only on a system's sensitivity but also on its ability to adapt to new climatic conditions. Kasperson et al., (2000) defines vulnerability as the degree to which an exposure unit is susceptible to harm due to exposure to a perturbation or stress and the ability or lack of the exposure unit to cope, recover or fundamentally adapt to become a new system or to become extinct. According to Tuner et al. (2003, p 8075), vulnerability refers to the degree to which a system, subsystem or system component is likely to experience harm due to exposure to a hazard be it perturbation or stressor. For Balica (2007 p 26), vulnerability is the extent to harms, which can be experienced by a system under certain conditions of exposure, susceptibility and resilience. For Damm, (2010), the term vulnerability is taken as a function of exposure, susceptibility, and capacities. According to Fekete (2010, p 31), vulnerability is both a state and a degree: everyone is vulnerable in the state of exposure to a hazard and is vulnerable to a certain degree: vulnerability changes in time and space and aims at identifying and explaining why the object of research is at risk and how risk can be mitigated.
While, IPCC (2007) relates vulnerability to the character, the magnitude and the rate of climate change and variation in addition to the susceptibility and limited coping capacity of a system and IPCC (2012a, p 32) shows how the concept of vulnerability has served as a guiding element to address disaster risk in the context of climate change and climate variability.
The similarity between all of these studies is that they agree on the three factors that define vulnerability. Thus, the vulnerability of a system is not only a function of exposure to hazards, perturbations and stresses alone but also resides in the sensitivity or susceptibility and in resilience or capacity of the system experiencing such hazards. Birkmann (2013, p 10) reviews vulnerability concept from various researchers and concludes that the concept of vulnerability stresses the fundamental importance of examining the preconditions and the context of societies and communities and elements at risk to effectively promote risk reduction and climate change adaptation.
Based on the various views on vulnerability shown above, flood vulnerability in the current study is viewed as the degree of experienced flood harms under certain condition of exposure, susceptibility and resilience factors within the human-environment systems. Therefore, flood vulnerability is taken here as a function of exposure, susceptibility and resilience.