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| void | surfqual_initState (int subcatchIndex) |
| | Initializes pollutant buildup, ponded mass, and washoff.
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| void | surfqual_getBuildup (int subcatchIndex, double tStep) |
| | Adds to pollutant buildup on subcatchment surface.
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| void | surfqual_applyAPIBuildup (int subcatchIndex) |
| | Applies the buildup of a pollutant over a subcatchment for a given time step.
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| void | surfqual_sweepBuildup (int subcatchIndex, DateTime aDate) |
| | Reduces pollutant buildup over a subcatchment if sweeping occurs.
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| void | surfqual_getWashoff (int subcatchIndex, double runoff, double tStep) |
| | Computes new runoff quality for a subcatchment.
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| double | surfqual_getWtdWashoff (int j, int p, double f) |
| | Finds wtd. combination of old and new washoff for a pollutant.
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Subcatchment water quality functions.
- Author
- L. Rossman
- Date
- Created: 2023-07-14 (Build 5.2.4)
-
Last edited: 2026-07-11
- Version
- 5.3
Subcatchment water quality functions.
Update History
Build 5.1.008:
- Pollutant surface buildup and washoff functions were moved here from subcatch.c.
- Support for separate accounting of LID drain flows included. Build 5.1.014:
- Fixed bug in computing effective BMP removal by LIDs. Build 5.2.4:
- Set low runoff flow concentrations to zero before computing runoff mass loads rather than after so that they match wet weather mass inflows reported for conveyance system nodes. Build 5.3.0
- Added support for API provided pollutant build up and washoff.
- Fixed the runoff quality continuity error introduced in Build 5.2.4. Zeroing the low runoff concentration ahead of the mass balance bookings (rather than only ahead of the reported load) left any pollutant load generated in that step assigned to no output category, so the mass was silently dropped. The washoff concentration is now computed whenever there is inflow. This affects subcatchments with LID controls (where capture approaching 100% drives the surface + underdrain outflow below the cutoff) and subcatchments without LID controls (wet deposition and/or runon while runoff is below the cutoff). Note the Build 5.2.4 rationale does not require zeroing the concentration: no cutoff is applied to node mass inflow, and the only cutoff lives in subcatch_getResults(), which zeroes the reported runoff rather than the newRunoff used for routing.
- Pollutant mass carried into the native soil by LID infiltration is now reported under Infiltration Loss (INFIL_LOAD) instead of being lumped into BMP Removal, so infiltration loss, treatment removal and underdrain/surface overflow export are accounted for separately. \TODO: Add support for tracking the mass balance of API provided pollutant build up and washoff seperately. \TODO: Concentration-based LID treatment (pollutant mass stored in the LID and released through the drain, overflow and infiltration) is not yet modeled; LID removal is still driven by volume reduction plus the underdrain REMOVALS fraction.
1.13.2