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Research

Publications

Everything on this platform is documented research: open national datasets with citable DOIs, an open accelerated modeling engine, and the coupled surface-water–groundwater methods behind them.

Read the preprint (SSRN) Reproducibility code & data
CONUS map of the national groundwater well inventory, wells colored by data tier
Simulated groundwater PFOS plume at a legacy AFFF site over satellite imagery
National map of measured soil PFAS sampling locations
Thread-scaling curves for the parallel SWAT+ engine across three processor generations

Data and code are released first — the manuscripts documenting each method carry an honest status label until they complete peer review.

Open national data

Released, versioned, and citable — the datasets are the deliverable; the papers document the methods.

A national inventory of well lithology and hydraulics for the conterminous United States
Submitted for peer review (2026)

A national inventory of well lithology and hydraulics for the conterminous United States

A living CONUS well-lithology database harmonized from state agency sources — the subsurface layer that turns a watershed model into a groundwater model. Openly released and citable.

An open, depth-resolved inventory of measured soil PFAS concentrations
Submitted for peer review (2026)

An open, depth-resolved inventory of measured soil PFAS concentrations

30,972 depth-resolved soil PFAS records from public agency reports across 41 states — the source-term layer for coupled PFAS modeling. Openly released and citable.

Coupled surface water – groundwater – PFAS modeling

Two-way SWAT+/MODFLOW 6 exchange carrying PFAS through soil, aquifer, and stream in one mass balance.

Legacy groundwater sustains in-stream PFAS loads: the groundwater pathway via two-way coupled SWAT+/MODFLOW 6
Preprint · Under peer review (2026)

Legacy groundwater sustains in-stream PFAS loads: the groundwater pathway via two-way coupled SWAT+/MODFLOW 6

A two-way daily coupling of SWAT+ and MODFLOW 6 carrying PFAS through both compartments — quantifying how much of the in-stream PFAS load arrives through legacy groundwater discharge rather than over the land surface.

Wurtsmith AFB: from contaminated soil to aquifer to stream, 1971–2024
Research demonstration

Wurtsmith AFB: from contaminated soil to aquifer to stream, 1971–2024

A five-decade coupled reconstruction of a legacy AFFF site — reproducing the "clean water table over a contaminated aquifer" enigma with measured soil concentrations as the only source term.

Platform & engine

The model-generation pipeline and the accelerated open SWAT+ engine that runs it.

Accelerating a regional hyper-resolution SWAT+ model without changing the science
In peer review (2026)

Accelerating a regional hyper-resolution SWAT+ model without changing the science

A reproducible profiling-to-parallelization methodology and a routing-aware shared-memory wavefront: up to 5.33× at 24 threads, ~7× end-to-end versus our single-core baseline build (near 8× versus unmodified upstream), byte-identical to the serial engine at every thread count. Open source.

Featured

Preprint · Under peer review (2026)

Automating High-Resolution SWAT+ Watershed Model Generation from NHDPlus HR and National Environmental Datasets

Vahid Rafiei (2026) · ORCID. Available as a preprint on SSRN (Elsevier's early-stage research platform) while under peer review.

The paper describes how SWATGenX turns public national data into inspectable, downloadable SWAT+ setups: NHDPlus HR hydrography, catchment preparation, HRU delineation, climate and soils inputs, QA checks, and the reproducible pipeline that assembles them at CONUS scale.

Cite this work

Rafiei, V. (2026). Automating High-Resolution SWAT+ Watershed Model Generation from NHDPlus HR and National Environmental Datasets. SSRN. https://ssrn.com/abstract=7022809

The reproducibility repository also ships a CITATION.cff for automatic citation. Journal, volume, and DOI will be added on acceptance.

More from this author

Further work — including vadose-zone PFAS transport (see the Wurtsmith case study above) — is in preparation. Track new work on the SSRN author page or the ORCID record.

Next steps

Example SWAT+ models
Methodology
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Page updated 2026-06-30.