An hourly‐scale scenario‐neutral flood risk assessment in a mesoscale catchment under climate change

Abstract

Reliable assessments of flood risks are essential to formulate robust adaptation policies to climate change. Although the scenario-neutral flood assessments have reduced the dependency on uncertain climate predictions, coarse temporal resolutions of rainfall-runoff modelling adopted for the stress tests may introduce appreciable bias to flood risks driven by climatic stresses. To refine the temporal scale of flow estimates, this study proposes to incorporate a multiplicative random cascade (MRC) scheme and a simple catchment model in the bottom-up flood risk assessment. Results showed that use of a daily flow indicator for the stress tests could considerably underestimate the impact of climatic change on flood risks. The non-linearity between daily and hourly peak flows could increasingly amplify flood risks as the mean and variance of daily precipitation become greater in the study catchment. The first-order catchment model combined with the MRC could acceptably estimate hourly peak flows and the catchment recession behaviours at high flows. This study suggests that subdaily flood indicators should be used in the scenario-neutral assessments for small or mesoscale catchments to prevent underprediction of flood risks. To expand the applicability of the bottom-up framework, we also suggest developing efficient tools that can perturb high-resolution weather time series for the stress tests. KEYWORDS climate change and flood risks, peak flow responses to climate change, scenario-neutral flood assessment, temporal scales of the response surfaces

Multivariate Flood Risk Analysis at a Watershed Scale Considering Climatic Factors

“…A scenario hypothesis is used to simulate the hydrological response of flooding under a certain climate scenario in the future and then analyze the flood risk [31][32][33]. The hydrological response to climate change is the basis of the study on the influence of climate change on flood risk.…”

Mapping the Sensitivity of Population Exposure to Changes in Flood Magnitude: Prospective Application From Local to Global Scale

“…To overcome the uncertainties and problems associated with model cascades, alternative approaches are currently being developed (Guo et al, 2017;Knighton et al, 2017;Kim et al, 2018;Broderick et al, 2019;Keller et al, 2019a;Keller et al, 2019b). In studies investigating the impacts of climate change on hydrology, a scenario-neutral approach has been used to analyze the sensitivity of river flows to changes in temperature and precipitation, where the observed rainfall and temperature data are modified by stepwise increases or decreases in the value of associated parameters.…”

Incorporating the logistic regression into a decision-centric assessment of climate change impacts on a complex river system

“…Among the decision-centric frameworks, the assessments based on the response functions of system performance have provided convenience in defining decision thresholds at which adaptation actions are required (e.g., Kim et al, 2018;Steinschneider et al, 2015a;Turner et al, 2014;Whateley et al, 2014;Brown et al, 2012;Prudhomme et al, 2010). They developed the relationships between system performances and climatic stressors (hereafter referred to as the response surfaces) via stress tests.…”

“…Nonetheless, uncertainty of the response surfaces cannot be neglected due to assumptions and simplifications associated with the stress tests. Kim et al (2018), for instance, showed how climate change risks could be underestimated if a modeling scale was inappropriately chosen. Kay et al (2014) emphasized the importance of uncertainty allowances being used alongside the response surfaces.…”