Evaluating flood control and drainage management systems from a productive efficiency perspective : a case study of the southwest coastal zone of Bangladesh

Abstract

Performance evaluation of flood defence systems is invariably carried out from an engineering perspective overlooking the productivity perspective, thereby leaving a gap in the literature of performance evaluation in the water resources management sector. Two competing flood control and drainage management (FCDM) systems, namely, the ‘silt-dredging and regulative-drainage management (SRM)’ and the ‘tidal river-basin management (TRM)’ systems were implemented in the Southwest coastal zone of Bangladesh as safeguards to protect agricultural production. There is a longstanding debate over the appropriateness of these systems in terms of providing conditions for sustainable agriculture. The lead executing agency, Bangladesh Water Development Board, was adamant to implement the hard engineering structural system, the SRM, while the stakeholders (i.e., the farmers and the fisher folk) insisted on the non-structural system, the TRM. However, this work evaluates these two contrasting and competing FCDM systems in terms of productive efficiency, in order to address primarily the gap in the literature of performance evaluation. The study develops separate econometric models for paddy production and fisheries production with each of the FCDM systems and estimates these models using stochastic frontier analysis to obtain technical efficiency (TE), yield-gap and potential yield increment (PYI) for paddy production, and cost efficiency (CE), cost-gap and potential cost saving (PCS) for fisheries production. The study results reveal that mean TE, CE, yield-gap and cost-gap are respectively 0.782, 0.807, 719.181 (kg) and 12542.71 (tk) with the SRM system, while these estimates are 0.769, 0.762, 807.324 (kg) and 14440.39 (tk) with the TRM in order. These findings indicate that SRM system marginally outperforms TRM system in terms of agricultural productivity. This is despite the SRM being more expensive to deliver, as well as the fact that, due to rise of relative sea-level with the SRM system, it is likely to become increasingly more expensive in the future. In contrast, the TRM system benefits from counteracting the rise of relative sea-level through land accretion by sedimentation in the floodplains in an environmentally friendly way, keeping the maintenance costs low.