Continental-Scale Streamflow Simulation Using Kriging in the NGIAB-NRDS NextGen Ecosystem
Hourly streamflow kriging is now operational within the NextGen Research Data Stream, delivering spatially complete estimates for all NextGen v2.2 hydrofabric catchments. This observation-based approach supports streamflow analysis, NWM calibration, forecasting, and data assimilation for ungauged basins.
Kriging-Based Streamflow Estimation
Process-based hydrologic models are subject to structural and forcing uncertainties throughout the modeling domain, yet these can only be evaluated where USGS gauge observations exist. There is a clear need for a data-driven, observation-based framework that provides spatially complete streamflow estimates with well-characterized uncertainty, independent of model structure. Recent results from the CIROH project "Developing and Benchmarking Data Assimilation Methods on a Standardized Testbed" suggest that a simple Kriging interpolation between USGS gauged locations is both scalable and accurate for producing such spatially complete streamflow fields. As a pure data-driven method, this interpolation cannot be used directly for forecasting, but it serves as a valuable "pseudo-observation" for streamflow analysis and historical reconstruction.