Living modelling record

Modelling Roadmap

This page records the actual development status of the HARE hydrological modelling work. A stage is marked complete only after the corresponding data, model configuration or result has been prepared and checked.

Current position: HEC-HMS design-flood modelling is complete. The SWAT watershed, HRU and climate-input stages are also complete, and two continuous SWAT simulations have been successfully run. Current work focuses on interpretation of hydrology and sediment behaviour, followed by sediment-management design and future historical calibration.

Current modelling stage

Overall Progress

HEC-HMS

Complete

Event-based rainfall-runoff modelling and 50-year design-flood analysis at the Hare diversion weir are complete.

SWAT

2 Runs

Watershed delineation, HRUs, climate preparation and two continuous simulations have been completed.

Current Focus

Results

Hydrology, erosion, sediment routing and field evidence are now being interpreted for engineering application.

Event hydrology

HEC-HMS Roadmap

Stage	Status	Current Record
Catchment delineation	Completed	Hare Weir catchment approximately 162.0 km²
Subbasin configuration	Completed	Five HEC-HMS subbasins
Curve Number development	Completed	Spatially weighted CN values prepared
Loss method	Completed	SCS Curve Number
Transform method	Completed	SCS Unit Hydrograph
Reach routing	Completed	Muskingum routing
Design rainfall	Completed	50-year 24-hour rainfall = 58.98 mm
Design-storm simulation	Completed	72-hour event simulation at 15-minute interval
50-year outlet peak	Completed	114.4 m³/s at Hare Weir
Runoff volume assessment	Completed	Approximately 2.73 million m³
HEC-HMS documentation	Completed	Model setup, results and figures documented

HEC-HMS status: the event-based design-flood assessment is complete and provides the present flood-design reference for the Hare diversion weir.

Continuous watershed modelling

SWAT Roadmap

Stage	Status	Current Record
Watershed delineation	Completed	161.95 km² final SWAT watershed
Subbasin generation	Completed	17 hydrologically connected subbasins
Land-use preparation	Completed	HARE 2026 land-use classes prepared for SWAT
Soil preparation	Completed	SWAT user-soil assignment completed
Slope classification	Completed	Five DEM-derived slope classes
HRU generation	Completed	Full HRU overlay with 0% elimination thresholds
Climate preparation	Completed	NASA POWER daily forcing, 2020–2025
Weather-grid preparation	Completed	16 spatial climate points
Relative humidity conversion	Completed	Percentage values converted to SWAT fractions
Hare-specific weather generator	Completed	HARE01–HARE16 WGEN stations
SWAT input database tables	Completed	Required model tables generated successfully
Simulation 1	Completed	Initial continuous daily simulation
Simulation 2	Completed	Hare-specific WGEN reference run
Hydrological interpretation	In progress	Water balance, daily flow and seasonal response
Sediment interpretation	In progress	Upland erosion, HRU hotspots and channel deposition
Field verification	In progress	Comparison with present Hare weir sedimentation
Historical SWAT calibration	Pending	Requires matching daily climate forcing for the historical 1980–1990 flow period

Current reference simulation

Simulation 2 — Present Reference Results

Mean Annual Rainfall

1665.5 mm

Mean annual precipitation reported by the SWAT Error Checker.

Surface Runoff

267.63 mm

Basin-average annual surface-runoff response.

Groundwater Return Flow

182.06 mm

Simulated groundwater contribution to streamflow.

Largest Daily Flow

211.6 m³/s

Largest current simulated daily outlet flow, occurring on 15 April 2024.

Average Sediment Yield

58.4 Mg/ha

Simulation 2 basin-average upland sediment yield.

Channel Deposition

96.23%

Error Checker indication of very strong simulated in-stream sediment deposition.

Calibration note: these are modelled results from the current reference configuration. They should not yet be treated as formally calibrated hydrological or sediment predictions.

Next engineering stage

Sediment Management and Headworks Reassessment

The SWAT analysis and present field observations both indicate that sediment management is a major issue for the Hare diversion system.

Catchment Measures

Investigate erosion-control measures in the principal sediment source areas, including:

bare-ground stabilization;
agricultural terracing where appropriate;
contour farming;
vegetative strips;
gully stabilization; and
localized check structures.

Headworks Measures

Investigate sediment-control measures at the diversion, including:

undersluices or scour sluices;
sediment flushing routes;
improved intake alignment;
sediment exclusion;
desilting basin requirements; and
operational flushing procedures.

Important: final sediment-control design requires field information on sediment grain size, sediment concentration, river-bed material, intake geometry, river levels and available flushing discharge.

Remaining modelling work

Future Tasks

Future Task	Purpose	Status
Historical climate reconstruction	Prepare daily meteorological forcing corresponding to the 1980–1990 historical flow observations.	Future
Historical SWAT simulation	Run the present watershed and HRU configuration for the historical observation period.	Future
Streamflow calibration	Compare simulated and observed flow using matching dates.	Future
Sediment field investigation	Obtain grain-size, concentration and deposition data.	Recommended
Sediment-control design	Develop the preferred flushing, exclusion and desilting arrangement.	Next engineering stage
Headworks reassessment	Integrate hydrology, hydraulics and sediment behaviour into the reconstructed Hare diversion design.	Ongoing

HARE modelling sequence

From Catchment Analysis to Engineering Design

Rainfall and Catchment Data
↓
HEC-HMS Design-Flood Analysis
↓
SWAT Watershed + HRUs + Climate
↓
Continuous Hydrology
↓
Erosion + Sediment Routing
↓
Field Verification at Hare Weir
↓
Sediment-Management Study
↓
Headworks Reassessment
↓
Historical Calibration + Final Documentation