1. Rainfall
Daily rainfall record, annual maxima, frequency analysis, adopted design rainfall and 24-hour design-storm preparation.
Rainfall workspace →HARE Revisited · Event-based flood modelling
HEC-HMS
The HEC-HMS branch converts design rainfall into catchment runoff and a flood hydrograph for the 162.035 km² Hare River watershed. The present reference simulation is the completed 50-year design event at the Hare Weir / irrigation headworks.
Accepted reference result:
58.98 mm / 24 h design rainfall →
114.4 m³/s peak discharge at
Sink-1 / Hare Weir, with
16.84 mm runoff depth and approximately
2.73 million m³ of simulated storm runoff.
Reference simulation
Current HEC-HMS model snapshot
Watershed area
162.035 km²
Subbasins
5
Routing reaches
2
Reference event
50-year
24-h rainfall
58.98 mm
Outlet peak
114.4 m³/s
Runoff depth
16.84 mm
Runoff volume
≈ 2.73 million m³
Peak timing:
the 50-year outlet peak is recorded at approximately
16:15 on 1 January 2000 in the simulation control period.
The outlet is Sink-1 / Hare Weir.
Build sequence
HEC-HMS work packages
The model is documented page by page so that the rainfall inputs, basin configuration, methods, simulation settings and final outputs can be reviewed independently.
2. Basin Model
Five subbasins, two routing reaches, two junctions and the final outlet at Sink-1 / Hare Weir, with documented areas and drainage structure.
Basin model →3. Methods & Parameters
SCS Curve Number loss, SCS Unit Hydrograph transform, no baseflow, Muskingum routing, lag times and adopted parameter values.
Methods & parameters →4. Simulation Runs
Meteorologic model, basin model, control specifications, 15-minute computation interval, return-period scenarios and simulation run log.
Simulation runs →5. Results
Accepted 50-year outlet hydrograph, peak discharge, runoff depth, runoff volume, routed-flow behaviour and graphical result elements.
Results →6. Validation & 1995 Check
Engineering comparison between the modern HEC-HMS rainfall–runoff simulation and the historical 1995 Log-Pearson Type III flood estimate.
Validation & 1995 comparison →How the model works
Rainfall to design flood
1 · Design rainfall
The adopted rainfall event is transformed into a 24-hour storm for use by the HEC-HMS meteorologic model.
2 · Rainfall losses
The SCS Curve Number method estimates infiltration and other abstractions before rainfall excess becomes direct runoff.
3 · Runoff transformation
The SCS Unit Hydrograph converts effective rainfall into subbasin runoff hydrographs using the adopted basin lag times.
4 · Channel routing
Muskingum routing transfers the upstream hydrographs through reaches R_1 and R_2 before they arrive at the Hare Weir outlet.
Accepted reference result
50-year design-event summary
| Watershed | Hare River watershed |
|---|---|
| Catchment area | 162.035 km² |
| Design return period | 50 years |
| 24-hour design rainfall | 58.98 mm |
| Outlet | Sink-1 / Hare Weir |
| Peak discharge | 114.4 m³/s |
| Peak time | 1 January 2000 · approximately 16:15 |
| Runoff depth | 16.84 mm |
| Approx. runoff volume | 2.73 million m³ |
| Historical 1995 50-year estimate | 59.183 m³/s |
Interpretation:
the HEC-HMS result is the hydrologic input to the hydraulic design of the
diversion works. The peak discharge must be used together with hydrograph
timing, runoff volume, hydraulic capacity, sediment passage, scour,
freeboard and river morphology.
Next hydrologic stage
Independent SWAT watershed simulation
The HEC-HMS reference simulation is now documented as the event-based rainfall–runoff model for the Hare headworks. The next independent modelling stage is the SWAT watershed simulation, which will provide a second hydrologic line of evidence for the reconstructed HARE Irrigation Project study.
Continue to the SWAT workspace →