TMDL watershed modeling with SWAT+
We deliver a SWAT+ model of your watershed that simulates daily flow in every stream segment and reports it at each of your stations, so every station has the flow record its flow-duration and load-duration curves need.
What the model is built from
Each model is built from NHDPlus High Resolution streams and catchments, USGS 3DEP elevation, gSSURGO soils, NLCD land cover, PRISM climate, and USGS stream gauges.
National data carries no permitted point-source discharges, so the model has none until your facilities' records are added in the project.
Nitrogen, phosphorus and sediment
The model also simulates the daily sediment, nitrogen and phosphorus leaving every reach, so a plan can see which subwatersheds carry the most.
Sediment, nitrogen and phosphorus are simulated, not fitted to measurements, unless fitting them to your monitoring data is part of the project.
SWAT+ as we build it does not simulate bacteria: the model supplies the flow, and the criterion and the monitoring data are your plan's.
Calibration, a separate step
Calibration fits the simulated streamflow to the observed daily discharge of a USGS gauge.
Calibration runs in the cloud and is reported with the run's chart and scores.
Where no USGS gauge measures your watershed, we tell you before the project starts which of three it gets: calibration at the larger gauged watershed that contains it; parameters carried over from a neighbouring watershed's calibration; or no calibration, labelled as such.
We have calibrated 43 automatically built models, 25 of them validated on years their calibration did not use.
What your team receives
You receive the SWAT+ project itself: your team opens it in SWAT+ Editor and runs it, and the files are yours.
We quote each TMDL project from its watershed, its monitoring stations and the loads it needs.
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