1. Modeling of a Watershed Basic Calibration Workshop LMRFC March 10-13, 2009 slide 1

2. NWS Hydrologic Modeling Basin A Basin B Operations Table Snow model A Rainfall-runoff model A Unit hydrograph A Convert discharge to stage 1 Display results 1 Rout hydrograph 1->2 Snow model B Rainfall-runoff model B Unit hydrograph B Add hydrographs 1+2 Convert discharge to stage 2 Display results 2 1 2

3. Requirements Need models of all process, natural or man-made that occur in a watershed, or adjust the data to remove the effects –Snow accumulation and melt –Soil moisture retention and movement –Flow in channels –Effects of reservoirs –Channel losses Need ability to combine models in the proper sequence to simulate what occurs in the watershed Need ability to combine results of models by adding, subtracting, weighing, etc. Need ability to display results in form of plots, tables, statistics Data for models –Time series of single quantities –‘time series’ of gridded values such as precipitation Operationally, may need to apply state adjustment procedures NWS Calibration Workshop, LMRFC March, 2009 slide 2

4. NWSRFS Operations Table Concept Operation –Hydrologic or hydraulic model –Updating procedure –Display of results (graphical or tabular) –Data manipulation algorithm Operations table –Procedure for combining operations in whatever sequence is needed for a particular application. Information passed from one operation to another by time series All input time series for each operation must have data values Future: pass information from one operation to another in the form of grids NWS Calibration Workshop, LMRFC March, 2009 slide 3

5. Summary of NWSRFS Operations Snow model Conceptual rainfall/runoff models: Sac, Nile Empirical rainfall/runoff models: 7 variations of API Channel response functions (UHG) Hydrologic routing models: Lag/K, layered coefficient, Muskingum Hydraulic (full dynamic) channel routing Reservoir models Stage discharge conversions Time series manipulation –Add –Subtract –Change t –Mult/divide –No missing –Weight Updating procedures: Kalman filtering Glacier model Consumptive use Plotting functions NWS Calibration Workshop, LMRFC March, 2009 slide 4