Using the National Weather Service Hydrologic Laboratory Research Distributed Hydrologic Model to Estimate Real-time Soil Moisture

For over 10 years the National Weather Service (NWS) River Forecast Centers (RFC) have been using the Hydrologic Laboratory Research Distributed Hydrologic Model (HL-RDHM) to forecast surface flow for the production of flash flood products and channel streamflow prediction. The output from this model has been quite beneficial in producing more useful products and services delivered from the NWS.

            As a by-product from the HL-RDHM streamflow forecasts, the Arkansas-Red Basin River Forecast Center (ABRFC) has also been producing daily soil moisture states computed from the HL-RDHM’s Sacramento Soil Moisture Accounting Heat Transfer (SAC-SMA-HT) operation for both upper and lower soil zones. However these products do not have a direct comparable relationship to actual soil saturation at specific soil depths. The ABRFC has since activated the frozen ground technique to its HL-RDHM SAC-SMA-HT operation to allow 4-km gridded soil moisture amounts to be computed at designated depths. These computations and resulting RFC products is of value to agricultural and other soil moisture interests.  

These computations should allow direct comparisons to be made versus actual soil moisture observations. A study was done using average and daily computed soil moisture output compared to in-situ soil moisture observations and their monthly average at various locations. Results of this study will be shown in this presentation.