The impacts of flooding and methods of assessment in urban areas of Bangladesh
This research is the first of its kind in Bangladesh. It focuses upon flood losses in urban sectors of the country’s economy. The broad research question is whether flood impacts in urban or non-agricultural sectors are important in Bangladesh, given that it is currently an agricultural economy. The research examines the applicability of existing urban flood impact assessment methods, and develops methods suitable to Bangladesh. An important aim is to accumulate a knowledge base of flood impacts in the urban or non-agricultural sectors. With appropriate modifications, flood loss assessment methods generated in developed countries may be applied in a developing country such as Bangladesh. However, the ‘synthetic’ approach of constructing standard potential flood loss data sets is not feasible. Using surveys of actual floods, the construction of reasonably high-quality ‘average’ data sets proves to be feasible, as floods in Bangladesh are not sparse. The construction of data sets through regressions is preferred because it is more realistic and cost-effective. The widely used unit-loss model is found to be applicable to appraisals of urban protection schemes. However, the successful application of the model depends on the accuracy of land use and land level survey data, and detailed hydraulic and hydrological information. In Bangladesh, this form of modelling is found to be suitable for project appraisals ranging from small to intermediate scale. Some methods, however, are suitable for up to full scale appraisals. The major achievement of the research is that flood loss potential for urban Sectors has been thoroughly investigated, providing flood loss data of a significantly higher quality that are available hitherto in Bangladesh. In providing these data the research is a significant advance upon the methods recommended within the existing FPCO Guidelines for project assessment, and those used in recent FAP urban protection studies. The assessments methods developed and the standard damage data sets constructed may now be used to appraise urban protections, which will also facilitate evaluation of agricultural projects more comprehensively through incorporating non-agricultural losses that can be averted in such schemes. The research reveals that the urban sectors of the economy are highly vulnerable to floods. Induced by rapid urbanisation, potential urban flood losses in Bangladesh are expected to be progressively more important in the future. Poverty is found to be fundamental to flood hazard vulnerability: the poorest of the poor have the most to lose in proportional (to value) terms. A high priority can now be given to protect urban and commercial centres in Bangladesh. Given limited resources in Bangladesh, low-cost non-structural measures are also important. Local knowledge and informal flood warning systems have a positive bearing on resilience building. Community cohesion, together with family kinships, are also important in this respect. Different types of floods (e.g. river flood, flash flood and tidal surge) are associated with differential impacts: tidal floods prove the most destructive. Flood impacts at the macro-level are not found to be as severe as those at the micro-level. The findings suggest that floods deepen poverty and help widen the income gap between rich and poor. This problem poses further research questions regarding ‘equity’ and sustainable development. Project appraisal methods using conventional ‘economic efficiency analysis’ need to be re-calibrated in order to confront the problems relating to inequity and sustainable development, especially in the context of existing socio-economic conditions in Bangladesh.