Bigbee-x/accra-flood-grid

Interactive 3D flood simulation of Accra's Odaw basin — one self-contained HTML file. 209k real buildings, real terrain, GPU shallow-water sim of the June 2026 storm, and intervention scenarios. # Accra // flood grid An interactive 3D flood simulation of Accra's Odaw basin — **one self-contained HTML file**, no server, no dependencies, works offline (only the optional live-forecast feature calls the internet). 491,187 real building footprints (OSM hand-mapping plus Google Open Buildings gap-fill where OSM is sparse), the city's mapped drainage network, real terrain, a 284-place gazetteer, and a GPU shallow-water simulation of the June 29, 2026 storm (~140 mm in 24h, the worst June on record). Open `dist/accra-flood-grid.html` in any modern browser, press **start storm**, and watch the water obey Accra's actual topography: it pools at Alajo, traces the Odaw corridor through Avenor and Adabraka, and floods Sakumono/Klagon and Mallam — the same neighborhoods in the real June 2026 damage reports. Nobody told the simulation where to flood. ## Why Accra floods every June, and every credible study points to the same causes: a low-lying basin funneled into one silted channel, drains choked with plastic, buildings on floodplains, and drainage built for a much smaller city. This project turns those causes into switches you can flip, each modelling a real fix Accra is debating: - **Clear the drains** — de-silt and de-plastic the storm drains (today's reality vs. maintained) - **Dredge the Odaw channel** — the stalled $350M GARID works - **Restore the wetlands** — give the Ramsar wetlands back so the ground soaks up rain - **Sea level at Korle outlet** — a high tide backs up the outfall and traps water inland And a **split-screen compare**: two full simulations of the same storm run side by side — drains clogged (today) on the left, your chosen fixes on the right — with a draggable wipe divider and a live "X% less flooding" readout. Drag the divider across any neighbourhood to see the two outcomes at the same spot. And it knows the city by name: - **210 real places** from the OSM gazetteer, labeled in the 3D scene with declutter and zoom tiers; flood-history ar …