Independent Consultant, Madrid, Spain.
Inter-American Development Bank, Washington, DC, USA.
Risk Anal. 2021 Aug;41(8):1345-1361. doi: 10.1111/risa.13642. Epub 2020 Nov 27.
Existing and projected economic losses caused by floods all over the world have generated a growing consensus about the need for investment in flood risk mitigation. Most of the evidence on the returns to risk reduction is based on cost-benefit analysis performed for specific measures, lacking a comprehensive appraisal of alternatives. This article presents an integrated approach to consistently prioritize potential flood mitigation measures in a river basin and determine the economically desirable investment level in flood risk reduction. An optimization model is developed to select the type, size, and schedule of flood risk mitigation measures over a planning horizon. The model is formulated as a dynamic mixed integer linear program and applied to a river basin where severe floods have occurred historically. A variety of individual and combinations of risk reduction measures are used as inputs for the model. Initial analysis is conducted for different scenarios of flood damage growth, investment financing constraints, and decisionmakers' preferences toward extreme and future losses. Results show that investment in flood risk reduction is economically justified in the basin. Investment is greater for higher rates of damage growth and aversion to extreme flood losses. Financing constraints only affect the rate of implementation of risk reduction measures in the initial periods. The proposed integrated approach can inform the design of investment plans for flood risk reduction based on sound economic principles, providing valuable support to decisionmakers.
现有的和预计的全球洪水造成的经济损失使得人们越来越认识到需要投资于洪泛区风险管理。关于减少风险的回报的大部分证据是基于对特定措施进行的成本效益分析，缺乏对替代方案的全面评估。本文提出了一种综合方法，用于在流域内始终如一地优先考虑潜在的洪泛区缓解措施，并确定减少洪泛区风险的经济上可取的投资水平。开发了一个优化模型，用于在规划期内选择洪水风险缓解措施的类型、规模和进度。该模型被制定为动态混合整数线性规划，并应用于历史上发生过严重洪水的流域。该模型将各种单独和组合的风险降低措施作为输入。针对不同的洪水破坏增长、投资融资约束以及决策者对极端和未来损失的偏好情景，对模型进行了初始分析。结果表明，流域内减少洪水风险的投资在经济上是合理的。对于更高的破坏增长率和对极端洪水损失的厌恶，投资更大。融资约束仅在初始时期影响风险降低措施的实施速度。所提出的综合方法可以根据可靠的经济原则为洪水风险管理投资计划的设计提供信息，为决策者提供有价值的支持。
