## 2 Risk Redistribution under the Kaldor-Hicks Compensation Principle
### Risk-Based Flood Management  
Management and coordination of measures/actions that are used to reduce flood problems can be considered to be flood management [32]. An effective flood strategy reduces risk by reducing hazards (by reducing the probability and/or intensity of flooding) or vulnerability (by reducing the susceptibility and/or exposure). The measures are selected and designed to achieve the desired results within the economic, social, and environmental limitations. Evaluation criteria need to be clear, transparent, and object-oriented and include social appraisal and economic and environmental evaluation due to nonstructural and structural technical requirements. The reliability of evaluation depends on the correct assessment of the inputs, such as flood frequency, the vulnerability of the exposed asset, and other risk factors [3].  
\"Flood management\" refers to the overall process involved in mitigating the extent of flooding and the resulting damage by flooding [18], whereas \"risk-based flood management\" is the combination of all actions that aim to meliorate overall activities in a floodplain [33]. Risk-based management is geared towards evaluating the projects for reducing, but not necessarily eliminating, the flood risk [34]. In practical terms, the chance of flooding can never be eliminated. However, the consequences of flooding can be mitigated by appropriate behaviors and actions [2]. The basic principle of flood risk management should be \"adjusting from both ends to achieve moderation\" [35]. Vulnerability and/or hazard parameters can be adjusted to improve the floodplain functions. The flood management options available can be defined as those that reduce the challenge and those that enhance the individuals' and society's ability to cope with the flood. Typically, a mixture of methods would be the most effective management technique.  
The most important task regarding flood management is to select the most effective and suitable measure from direct (flood abatement, flood control, and flood alleviation) and indirect measures (involving structural and nonstructural measures) [17; 36]. A risk-based assessment enables policy-makers to focus on the outcomes and, thus, results in a set of the most suitable flood management measures. Risk-based flood management provides a rationale to spend resources on flood management options [3]. Resources can be spent in proportion to the risk involved, whereas the risk arises due to the combined environmental, social, and economic impacts of flooding. Hence, risk-based flood management facilitates the effective selection of different options. The research conducted by [PERSON], et al. [37] discussed the meteorological, hydraulic, and statistical fields of knowledge. In another similar attempt, a multivariate statistical model was set up to represent a typical probability distribution of measured river or sea level data at multiple locations by [PERSON] et al. [38] for the development of a risk-based assessment methodology for the UK. A proposed stepwise framework to evaluate the efficiencies of the flood management scheme is presented in Figure 1. The proposed framework is fitted into the recommended context of ISO Guide 31000 [39] to ensure the standardization of the approach.