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Evaluation of CMIP6 HighResMIP for Hydrologic Modeling of Annual Maximum Discharge in Iowa
Journal article   Open access   Peer reviewed

Evaluation of CMIP6 HighResMIP for Hydrologic Modeling of Annual Maximum Discharge in Iowa

Alexander T. Michalek, Gabriele Villarini, Taereem Kim, Felipe Quintero, Witold F. Krajewski and Enrico Scoccimarro
Water resources research, Vol.59(8), e2022WR034166
08/2023
DOI: 10.1029/2022WR034166
Appears in  UI Libraries Support Open Access
url
https://doi.org/10.1029/2022WR034166View
Published (Version of record) Open Access

Abstract

The High‐Resolution Model Intercomparison Project (HighResMIP) experiments from the Coupled Model Intercomparison Phase 6 represent a broad effort to improve the resolution, and performance of climate models. The HighResMIP suite provides high spatial resolution (i.e., 25‐ and 50‐km) forcings that have been shown to improve the representation of climate processes. However, little is known about their suitability for hydrologic applications. We use outputs from the HighResMIP suite to simulate annual maximum discharge with the Hillslope‐Link Model (HLM) at ∼1,000 river communities across Iowa. First, we assess whether the runoff from the climate models can be directly routed through the river network model in HLM to estimate annual maximum discharge. Runoff‐based simulations can capture the empirical distribution of flood peaks in five of the 10 models/members assessed. Next, we force the HLM with precipitation, temperature, and potential evapotranspiration from HighResMIP models to simulate flood peaks, finding all models/members produce empirical distributions similar to our reference. However, significant biases exist in the model/member forcings as correct flood response is being generated for the wrong reason. To improve their suitability for community‐level assessment, we use nine statistical approaches to bias‐correct and downscale HighResMIP precipitation to a 4‐km resolution. The bias‐correction and downscaling of climate model precipitation performs well for all models/members. Furthermore, we do not find significant changes in the magnitude flood peak projections for Iowa based on the HLM forced with HighResMIP outputs, or based on routed runoff, while there are indications that the variability in flood peaks is projected to increase across the state. Key Points High‐Resolution Model Intercomparison Project (HighResMIP) runoff routed through a hydrologic model generates realistic distributions of annual maximum discharge for 5 of 11 realizations assessed HighResMIP precipitation forcings generate realistic flood peaks for all realizations assessed after bias‐correction and statistical downscaling Changes in flood peaks are not detected for the future but there is an overall increase in variance at 24% of the location in Iowa
 bias‐correction downscaling floods global climate models HighResMIP hydrologic modeling UIOWA OA Agreement

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