Every rainstorm turns a small urban creek into a conveyor belt of plastic that rides the current to the sea. Cities want to catch it, but the engineering studies that pick a single boom location routinely cost six figures and take most of a year.
We built GRIME to shrink that gap: a free browser tool that scores every meter of any stream a user draws on a map. It runs a D8 flow model on USGS 3DEP ten-meter elevation data, then blends 27 parameters spanning litter generation, hydrologic transport, downstream ecological and environmental-justice impact, and deployment feasibility into a two-level weighted score, cross-checked against Manning’s equation and stress-tested with a 10,000-iteration Dirichlet Monte-Carlo run.
Applied to Ellerbe Creek, GRIME flagged 8 of 10 debris hotspots a local group had logged over a decade (80% sensitivity; 95% Wilson CI 49–94%) and cut estimated planning cost by more than 95%.
On an independent statewide test against 27 anthropogenic litter-trap sites documented by Waterkeepers Carolina, it recovered 22 (81.5%).
A bridge-anchored boom, sized to the sites GRIME picks, completes the pipeline from pixel to hardware.
