Abstract
Storm velocity (i.e., direction and speed) and structure (i.e., shape and intensity) play a critical role in streamflow response. These characteristics determine the timing and magnitude of precipitation fluxes across the watershed that drive runoff generation and conveyance along the river network. While previous efforts have used spatially explicit hydrologic models to assess the role of storm properties in streamflow magnitude, their computational demand significantly limits the range of scenarios that can be explored, hindering our ability to systematically identify critical conditions leading to extreme events. To address this technical gap, we introduce the Directional Unit Hydrograph (Directional-UH) model, a parsimonious approach based on the classic theory of the Unit Hydrograph. The Directional-UH extends the original theory by relaxing the assumption of spatial uniform rainfall and incorporating storm direction and speed into the unit hydrograph function. The model conceptualizes storms as rectangular structures with constant intensity moving along a linear trajectory with constant speed. We verify and validate our conceptualization by comparing with simulations, based on observations of extreme rainfall events, of the distributed hydrological model Hillslope-Link-Model (HLM) in the Turkey River basin in Iowa, USA. Then, the Turkey River basin is used as a testbed to illustrate three practical applications of the Directional-UH model. First, we identify the storm trajectory that produces the highest peak flow response. Second, we determine the storm characteristics that maximize the peak flow response by synchronizing storm motion and flood wave; we refer to this as the resonance condition. Third, we systematically explore the compounding effects of consecutive storm events with different trajectories to identify critical combinations that exacerbate the peak flow magnitude. The results on our testbed demonstrate that storm velocity has the potential to increase by a factor of two the peak flow magnitude when compared to stationary storm events. Overall, the parsimonious nature of the Directional-UH model offers a unique and valuable tool for modeling, predicting, and interpreting rainfall-runoff dynamics through the lens of storm direction, speed, and structure.
| Original language | English |
|---|---|
| Article number | 130422 |
| Journal | Journal of Hydrology |
| Volume | 627 |
| DOIs | |
| State | Published - Dec 2023 |
Funding
Notice: This manuscript has been co-authored by staff from UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). This research was funded by the U.S. Department of Energy, Office of Science, Biological and Environmental Research . This work is a product of two programs: (i) Environmental System Science Program, as part of the River Corridor Scientific Focus Area project at Pacific Northwest National Laboratory, the Watershed Dynamics and Evolution (WaDE) Science Focus Area at Oak Ridge National Laboratory, and the IDEAS-Watersheds project, and (ii) Data Management Program, as part of the ExaSheds project. Additional support was provided by the National Science Foundation, USA (awards EAR-1830172 , OIA-2020814 , and OIA-2312326 ). This research used resources of the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under contract no. DE-AC05-00OR22725. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the DOE under contract no. DE-AC05-00OR22725. The scripts to implement the Directional-UH are publicly available at https://github.com/gomezvelezlab/Directional-UH . This research was funded by the U.S. Department of Energy, Office of Science, Biological and Environmental Research. This work is a product of two programs: (i) Environmental System Science Program, as part of the River Corridor Scientific Focus Area project at Pacific Northwest National Laboratory, the Watershed Dynamics and Evolution (WaDE) Science Focus Area at Oak Ridge National Laboratory, and the IDEAS-Watersheds project, and (ii) Data Management Program, as part of the ExaSheds project. Additional support was provided by the National Science Foundation, USA (awards EAR-1830172, OIA-2020814, and OIA-2312326). This research used resources of the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under contract no. DE-AC05-00OR22725. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the DOE under contract no. DE-AC05-00OR22725. The scripts to implement the Directional-UH are publicly available at https://github.com/gomezvelezlab/Directional-UH.
Keywords
- Directional unit hydrograph
- Peak flow
- Storm motion
- Storm velocity
- Width function