1. Modelling the rainfall-runoff process
Available Rainfall Runoff (RR) models:
UHM
NAM
SMAP
URBAN

2. Modelling the rainfall-runoff process (NAM)
POTENTIAL EVAPORATION
MODEL
PARAMETERS
RUNOFF COMPONENTS
EVAPORATION
RECHARGE

3. NAM : “nedbør-afstrømnings model”
Describes the land phase of the hydrological cycle
The NAM is a lumped, conceptual model:
lumped catchment regarded as one unit.
parameters are average values
conceptual based on considerations of the
physical processes
Similar models: Stanford, SSARR, HBV, SMAR,..

4. Types of Application General hydrological analysis
- runoff distribution
- estimates of infiltration / evaporation
Flood Forecasting
- subcatchment inflow to river model
- links to meteorological models
Extension of streamflow records
- advanced gap-filling
- improved basis for extreme value analysis etc.
Prediction of low flow
- for irrigation management
- for water quality control

5. The NAM Model
equations

6. NAM, Initial conditions
Data to be specified:
Initial Water Content of Surface and Root zone storages
Initial values for Overland flow and Interflow
Initial Groundwater Depth
Recommended to disregard the first half year or so of the results to eliminate erroneous Initial Conditions!

7. NAM, Model Calibration
Most NAM Parameters of empirical nature => values must be determined by Calibration:
Water balance in system
Runoff hydrographs, peak and shape
Comparison of Runoff results with observations
Generally recommended to change only one parameter between each run !

8. NAM, Model Calibration
1. Manual Step-by-step procedure (changing one variable at a time)
2. Autocalibration Automatic optimisation routine using multi-objective optimisation strategy objectives: 1) Overall Volume error (= water balance) 2) Overall root mean square error (= hydrograph shape) 3) average root mean square error of peak flow events 4) average root mean square error of low flow events
Easy to use - BUT EVALUATION OF VARIABLE VALUES
REQUIRED TO JUDGE HYDROLOGICAL SENSIBILITY

9. NAM simulation, Liver creek

10. RR Parameter editor
Editing of Model-specific parameters for Rural Catchments :
NAM Model-specific parameters comprise:
Surface, Root-zone and Snow melt data
Ground water data
Initial Conditions
Irrigated Area
Editor-file: *.rr11

11. RR Parameter editor (NAM)
Example:
Surface-Rootzone variables

12. RR Input to HD Simulation
Inclusion of Runoff results in River model:
1) RR-simulation (produce RR Result-file)
2) Specify Catchment definitions in Network Editor (input to single points or distributed along reach)
3) Specify RR Result-filename in Simulation Editor