**6. Opportunities for flood risk analyses through simplified approaches and free and open geospatial data in the less developed societies**

Kovacs *et al.* [56] compiled a French technical report of several simplified approaches to flood risk analyses in the developing countries. These techniques are simplified in theory and often require utilise freely available datasets for flood risk analyses and protection of critical infrastructure in the less developed societies. Several other attempts have been made in the literature. The prospects within these simple techniques to enable stakeholders lessen the threats of flooding on critical infrastructure and sustainable development are significant. Hammond *et al.* [57] developed a modified Drivers-Pressures-State-Impact-Response (DPSIR) framework which enables policy makers to evaluate strategies for improving flood resilience in cities. Nkwunonwo *et al.* [49] proposed the new scheme, *GFSP-1,* to model urban flooding using a minimum of data. The model which was implemented in a MATLAB environment was tested using the flooding event of year 2000 in Portsmouth, UK, and later used to simulated the historic flooding of year 2011 in the Lagos area of Nigeria. See *et al.* [58] utilised an open data approach which includes open street map and field paper to map urban drainage infrastructure in the Philippines. Results emerging from these simplified approaches correlate positively with real life data, and have been effective in assessing flood risk and vulnerabilities, and providing realistic feedbacks to stake holders.

The major weakness in these simplified approaches is the lead time in moving towards an integrated flood risk management. This is because of many assumptions made to actualise data fitting in the simple methods, and the inability of the simple techniques to capture all the physical parameters and nexus around the variables that motivate flooding within catchment area. This increases epistemic and aleatory uncertainty, and makes it hard to generalise the methods towards a more effective stimulus in flood risk management. Flood risk is an aggregate of multiple factors – hazard, exposure and vulnerability – drawing from Crichton's risk triangle [59]. Land use analyses and flood modelling are able to evaluate the magnitude of exposure and flood hazard (depth and extent along with velocity of flood water) [9, 60, 61]. Vulnerability is a bit more practical because of its conceptualization and theories that underpin its analyses. In the current literature, flood vulnerability is a measure of elements at risk of flooding because they lack coping capacity or any form of adaptive mechanism. It is an ideal science culture to includes community participation in analysing flood vulnerability. This is

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*Flood Risk Analysis for Critical Infrastructure Protection: Issues and Opportunities in Less…*

standard technique in the developed societies, and few authors have discussed its application in the Lagos area of Nigeria. Although, data paucity and challenges adapting existing methodologies to new case studies often stand in the way of an ideal vulnerability analyses, participatory approaches for collecting informal knowledge on exposed elements and vulnerabilities from the population and local actors is invaluable towards assessment of vulnerability to flooding. Douglas *et al.* [19] Adelekan [13, 15], and Salami *et al.* [62] used this approach in the Lagos area of Nigeria, and the result have been fundamental to decision support in flood risk

One clear insight into stare-of art methodologies for vulnerability assessment is the importance of indicators as proxies to vulnerability variables. Several studies have applied this method for examples Müller *et al.* [63] and Tapia *et al.* [64] and the outcomes demonstrate how the various types of vulnerability – physical, economic and social – not only relate to various dimensions of the society, but also varies according to the complexity and main determinants of sustainable development. This understanding plays important roles in protecting critical infrastructure from flooding, bearing in mind the question of what makes a critical infrastructure vulnerable? For example, social vulnerability is based on social factor such as age, gender, socio-economic status [65], an idea which Nkwunonwo [41] applied, using demographic distribution from Nigeria's 2006 census to assess the social vulnerability of Lagos to urban flooding. Indicator-based vulnerability analyses is often complicated by the lack of method to measure a particular indicator. In such a situation, expert elicitation based on observed vulnerabilities and impacts following a previous catastrophic event can been used for vulnerability assessment and modelling. This is a simple approach that serves the purpose and addresses the gap

Flooding experiences in the Lagos metropolis of Nigeria are overwhelming and has remained an issue of incessant debate. Although there are present efforts at tackling the hazard, success so far has arguably been limited and ample discussion regarding this condition are critical. Whilst flooding is generally accepted as an inevitable phenomenon in present day environment, reducing its impacts on people and the environment is a significant priority for many regional and international flood management initiatives and directives [3, 66]. To achieve the sole aim of flood risk reduction which is "living with floods rather than fighting them", flood modelling and assessment of vulnerability to flooding are fundamental operations and have been applied in many developed countries such as the United States, United Kingdom and Netherlands [67]. However, for the Lagos metropolis of Nigeria, flood

modelling and assessment of vulnerability to flooding have been skimped.

As a critical focus, this chapter makes attempts to bridge the gaps in knowledge and practice of flood risk reduction in the Lagos area and investigates the key reason why these approaches were skimped in the Lagos area. It is argued that unless these critical issues such as limitation in data, legislation and policy and mismatch in sustainable development, the application of flood modelling and assessment of vulnerability to flooding in the Lagos metropolis of Nigeria will remain unrealistic. Moreover, simplified approaches and freely available and open source datasets create opportunities to undertake flood risk assessment despite the issues that cause severe limitations. Research is needed to provide bespoke methodologies that will take advantage of these resources to provide workable feedbacks to stake holders

*DOI: http://dx.doi.org/10.5772/intechopen.95364*

in flood risk assessment in developing societies.

and flood risk management policy males.

**7. Conclusion**

management within the area.

#### *Flood Risk Analysis for Critical Infrastructure Protection: Issues and Opportunities in Less… DOI: http://dx.doi.org/10.5772/intechopen.95364*

standard technique in the developed societies, and few authors have discussed its application in the Lagos area of Nigeria. Although, data paucity and challenges adapting existing methodologies to new case studies often stand in the way of an ideal vulnerability analyses, participatory approaches for collecting informal knowledge on exposed elements and vulnerabilities from the population and local actors is invaluable towards assessment of vulnerability to flooding. Douglas *et al.* [19] Adelekan [13, 15], and Salami *et al.* [62] used this approach in the Lagos area of Nigeria, and the result have been fundamental to decision support in flood risk management within the area.

One clear insight into stare-of art methodologies for vulnerability assessment is the importance of indicators as proxies to vulnerability variables. Several studies have applied this method for examples Müller *et al.* [63] and Tapia *et al.* [64] and the outcomes demonstrate how the various types of vulnerability – physical, economic and social – not only relate to various dimensions of the society, but also varies according to the complexity and main determinants of sustainable development. This understanding plays important roles in protecting critical infrastructure from flooding, bearing in mind the question of what makes a critical infrastructure vulnerable? For example, social vulnerability is based on social factor such as age, gender, socio-economic status [65], an idea which Nkwunonwo [41] applied, using demographic distribution from Nigeria's 2006 census to assess the social vulnerability of Lagos to urban flooding. Indicator-based vulnerability analyses is often complicated by the lack of method to measure a particular indicator. In such a situation, expert elicitation based on observed vulnerabilities and impacts following a previous catastrophic event can been used for vulnerability assessment and modelling. This is a simple approach that serves the purpose and addresses the gap in flood risk assessment in developing societies.
