Flood basins & dikes
Optional Enhanced feature: drag earth embankments on the floodplain to seal a basin around farms. After the inundation, sealed land keeps more fertility and moisture. Default is OFF (original Pharaoh farming).
What it does
- Enable Floodplain dikes / basin irrigation under Features → Gameplay.
- Build Dike (Infrastructure, next to Irrigation Ditch / Water Lift) as a drag strip on floodplain or its edge.
- Close a contour around floodplain farms. Use a sluice (road on dike) for cart access without breaking the seal.
- After the flood, sealed tiles get a fertility bump and farms grow a little faster; canals inside decay slower.
- A hole in the contour (or Osiris destroying the crest) drops the bonus until you repair.
This is not Pharaoh/Cleopatra parity — the original has no placeable dike. “Holding water” is a fertility / wet-window bonus after the flood, not a rewrite of how the Nile fills the plain.
Placing dikes
| Allowed | Blocked |
|---|---|
| Floodplain; clear land adjacent to floodplain; replace own dike; road|dike sluice | Deep water, rock, elevation, canals, foreign buildings, meadow far from the plain |
Labor cost is zero. Pure dike tiles are impassable; road on dike walks as a normal road. Dikes survive inundation (crest stays dry).
Sealed bonuses
- Fertility — extra restore when the tile floods (stronger compensation on poor floods).
- Farm progress — about +15% daily growth while labor is present.
- Canal hold — water in sealed canals decays at half rate; irrigation does not stamp across the crest.
Breach
When Osiris curses the city so that the next flood will destroy farms, that same flood also tears 1–3 perimeter dike tiles and posts a message. Perfect/excellent inundation quality alone does not breach dikes. Clear a crest tile yourself anytime to drain a basin on purpose.
Overlay
Overlays → Other → Flood basins tints sealed interiors and highlights dike crests (only useful while the feature flag is on).
Developer Reference
Flag: gameplay_enhanced_flood_basins
Dike placement and sealed flood basins — covered on this page.
Engine: src/building/building_dike.*, src/grid/basin.*, floodplain / canals hooks.
Overlay: src/overlays/city_overlay_flood_basin.*, OVERLAY_FLOOD_BASIN
Tests: tests/96_dike_place.js, 98_flood_basin_seal.js, 99_flood_basin_bonus.js, 107_flood_basin_irrigation_hold.js, 111_flood_basin_breach.js
Message: message_dike_breach (id 523)