LWI Region 3 Modeling Overview

3 Hydrologic and Hydraulic Modeling Methodology

3.1 ANALYSIS OF RECORD FOR CALIBRATION (AORC) The AORC is a high-resolution, gridded meteorological dataset developed primarily for hydrologic modeling and analysis across the United States. Maintained by the National Weather Service Office of Water Prediction, this dataset provides precipitation and other atmospheric variables on a standardized Standard Hydrologic Grid (SHG). The AORC is widely used in water resource management, flood forecasting, and environmental modeling. AORC precipitation data can be incorporated into hydrologic models as a meteorological boundary condition, typically through the RAS unsteady flow file in HEC-DSS format.

3.1.1 Data Sources and Specifications AORC integrates multiple data sources to ensure accuracy and spatial/temporal coverage: { Next Generation Radar Data (NEXRAD) (National Oceanic and Atmospheric Administration [NOAA]) { Gauge-based precipitation data (National Weather Service, USGS) { Satellite observations { Reanalysis products (e.g., National Centers for Environmental Prediction/National Center for Atmospheric Research Reanalysis)

SPECIFICATIONS:

SPATIAL RESOLUTION: Approximately 4 kilometers TEMPORAL RESOLUTION: Hourly

TIME SPAN : Typically from 1979 to near present

3.1.2 Development Process The AORC dataset is produced through a multi-step process: 1. Data collection: combines radar, satellite, ground-based gauges, and numerical model data 2. Bias correction: adjusts data using ground-truth measurements (e.g., rain gauges) 3. Spatial interpolation: creates continuous, gridded fields 4. Temporal aggregation: compiles data into hourly intervals 5. Validation: compares with independent datasets for model calibration and quality assurance

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LWI REGION 3 TRAINING

LOUISIANA WATERSHED INITIATIVE