Distributed Parameter Hydrologic Modeling and NEXRAD for River Forecasting: Scale Issues Facing the National Weather Serviceby Michael Smith,
Dong Jun Seo,
Abstract: With the advent of NEXRAD (Next Generation RADar), the National Weather Service has the opportunity to move from current lumped parameter modeling to more of a distributed parameter hydrologic modeling approach for river forecasting. However, this high resolution precipitation data poses the problem of calibration at one spatial and temporal scale while using the models operationally with NEXRAD data at a finer spatial and temporal scale. Until national NEXRAD coverage exists for a long enough time period to prove useful for calibration, understanding must be gained as to how to adjust calibrated model parameters to account for runoff volume differences resulting from using high resolution rainfall inputs. To examine this, a synthetic watershed was modeled using various sized computational elements using 9 months of archived NEXRAD rainfall data. Results indicate that finer spatial and temporal scales result in the generation of more total runoff and fast response runoff. Tests indicate that hydrologic model parameters are not transferrable across scales. When calibrating at a lumped scale and then disaggregating the basin for operational forecasting, certain parameters must be adjusted in order to recalibrate the hydrologic model.
Subject Headings: Hydrologic models | Parameters (statistics) | Data processing | Calibration | Scale models | Forecasting | Runoff | Rivers and streams
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