Sandbag replacement systems - A nonsensical and costly alternative to sandbagging?

Abstract

In addition to flood defence with sandbags, different sandbag replacement systems (SBRSs) have been available for a number of years. The use of sandbags is time-consuming as well as highly intensive in terms of materials and personnel. In contrast, SBRSs are reusable and require lower costs in terms of helpers and logistics, offsetting the comparatively higher initial investment costs through repeated use. So far, SBRSs have rarely been used in Germany in operational flood protection. The reasons lie in different financing modalities of investment, operational costs and low confidence in the technical performance of SBRSs. These problems are addressed by a research programme at the Institute of Hydraulic Engineering (IWA), City University of Applied Sciences, Bremen. A series of systematic large-scale tests of sandbag systems and SBRSs with a focus on functionality, stability and handling was carried out. The results showed that the majority of the SBRSs tested are able to provide protection comparable to that of sandbag systems but with a significantly reduced use of materials, simplified logistics and fewer helpers. Nevertheless, it is advisable to develop and perform well-defined certification tests for SBRSs, in order to define clear instructions for and to identify limits to the use of certain SBRSs. For example, not all systems work equally well on different surfaces. Supplementary to the practical tests, costs of the procurement and use of various sandbag systems and SBRSs were determined on the basis of realistic scenarios. This provides a methodology as well as concrete figures to cost the provision and use of different protection systems from a holistic perspective. It turns out that the higher investment costs of the SBRSs investigated compared to sandbag systems are already offset on the second use of the reusable systems.