Among the issues listed, the most difficult to assign monetary values to the costs and benefits of flood mitigation strategies is protecting ecosystems.
Ecosystems provide a range of services that are often hard to quantify in economic terms, such as biodiversity, water filtration, carbon storage, and recreational benefits. While approaches like contingent valuation and other methods can estimate the economic value of ecosystem services, these valuations can be highly subjective and variable. In contrast, the costs associated with protecting homes, businesses, infrastructure, and communication systems can typically be more easily quantified based on repair or replacement costs, insurance values, and economic impacts from downtimes.