Producing valuable information from hydrologic models of nature-based solutions for water

Abstract

Abstract Nature-based solutions (NBS) are an increasingly popular approach to water resources management, with a growing number of projects designed to take advantage of landscape effects on water flow. As NBS for water are developed, producing hydrologic information to inform decisions often requires substantial investment in data acquisition and modeling; for this effort to be worthwhile, the information generated must be useful and used. We apply an evaluation framework of salience (type of information), credibility (quality of information), and legitimacy (trustworthiness of information) to assess how hydrologic modeling outputs have been used in NBS projects by three types of decision makers: advocates, implementers, and analysts. Our findings, based on documents and interviews with watershed management programs in South America currently implementing NBS, consider how hydrologic modeling supports two types of decisions for NBS projects: quantifying the hydrologic impact of potential and existing NBS and prioritizing where NBS might be sited within a watershed. To help inform future modeling studies, we identify several problematic assumptions that analysts may make about the credibility of modeled outputs for NBS when advocates and implementers are not effectively engaged. We find that salient, credible, and legitimate results in applications evaluating NBS for water are not always generated in the absence of clear communication and engagement. Integr Environ Assess Manag 2022;18:135–147. © 2021 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). KEY POINTS Hydrologic information can be evaluated based on salience (relevance of information), credibility (quality of information), and legitimately (trustworthiness of information); our interviews suggest salience and legitimacy are critical to whether model outputs are useful and used. We identified three key target audiences in NBS projects—implementers, advocates, and analysts—with distinct information needs; quantifying the hydrologic impact of NBS is of interest to all three audience types, but for different reasons. Interviews about the type and sophistication of hydrologic models necessary for NBS projects in practice suggest that simpler models that gain legitimacy because they are more easily explained can provide sufficiently credible information to take action. Mutual understanding of the aims of the project among implementors, advocates, and analysts is critical to ensure that the actual variable of interest is identified and modeled and that non-hydrologic constraints are considered.

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