Effectiveness of emergency measures for flood prevention

Abstract

Emergency measures, such as sandbags, are often used during flood events to prevent breaches in flood defences. However, there is limited insight into their contribution to flood prevention. This paper describes a method to determine the reliability of a system of flood defences including emergency measures. The reliability of the emergency measure depends on the completion of three events: 'Detection' , 'placement' and 'construction' . Both detection and placement can fail due to human error or insufficient time; construction can fail due to structural failure. The method was applied to a case study in the Netherlands, in which the reliability of a flood defence system including emergency measures was determined. We found that emergency measures can increase the reliability with a factor 1.5-4, depending on the considered failure mode of the dike. Failure of detection and placement, and the underlying human reliability, had the highest contribution to the failure probability. Emergency measures proved to be cost effective, but are still less cost effective as traditional reinforcements. They could play a role as an interim solution to reduce flood risk.

Framework for assessing the performance of flood adaptation innovations using a risk‐based approach

“…Using these methods, updated safety standards for flood defences have been derived based on economic damages and loss of life (Jonkman, 2007;Jonkman, Kok, & Vrijling, 2005;Kolen, 2013;Rijkswaterstaat, 2015;Slijkhuis, van Gelder, & Vrijling, 2001;Vrijling, Van Hengel, & Houben, 1998). The new methods constitute a significant advance in the field of flood risk management (Vrijling, 2001) and provide opportunities to include the effectiveness of previously neglected solutions in the reliability and risk assessment of flood defences as shown by Lendering et al (2016).…”

“…To provide the necessary information to support riskinformed decision making, four performance indicators (PI) are used: effectiveness, durability, reliability, and cost (Table 2). In developing these PIs, different frameworks for evaluating the performance of different types of innovations were reviewed, including temporary flood barriers (Lendering et al, 2016;Margreth & Romang, 2010;Wibowo & Ward, 2016) and early flood warning systems (Sättele, Bründl, & Straub, 2015;Sättele, Bründl, & Straub, 2016). While recognising that tests and results for individual innovations may vary, the PIs are generally applicable and relevant for all flood adaptation innovations.…”

“…The operator error is estimated to be 1/50 per task according to the approach developed by Lendering et al (2016) to assess the reliability of emergency measures for flood prevention, assuming the operator operates at a rule-based level (details are provided in the Appendix S1, Supporting Information). Sliding failure (1/50 per use) will be governing considering the smooth surface of the entrance tiled floor.…”

“…Examples include temporary flood barriers, green infrastructure and early flood warning systems. Due to limited experience with their operational performance, end‐users are often hesitant to implement these innovations as key components in flood risk reduction systems instead falling back on more conventional interventions like sand bags and soil berms even though they have widely recognised limitations (Leeuw, Vis, & Jonkman, ; Lendering, Jonkman, & Kok, ; Wibowo & Ward, ). In addition, risk‐based approaches often require information about the performance of solutions that is not typically provided by innovators.…”

Failure probability of regional flood defences

“…An alternative to this empirical method is to determine the failure probability of the drainstop with a human reliability analysis, an example of such an analysis is given in [5,6].…”