Description
The Flood Drainage Channels form an intricate network beneath and between the settlement's structures, carved into the coral bedrock and lined with fitted stones where the natural rock proves too porous. The system follows the natural contours of the Spine Bars, using gravity to guide water from the highest points of the settlement down toward the tidal flats where it can safely rejoin the sea. The main channels are approximately two feet wide and eighteen inches deep, sized to handle the volume of water that accumulates during the worst storm surges while remaining narrow enough to step across easily during normal conditions.
The channel walls are lined with carefully fitted stones, their surfaces carved with traditional wave patterns that serve both decorative and functional purposes. The carved grooves actually help direct water flow and reduce turbulence, allowing the channels to move water more efficiently than smooth surfaces would. At regular intervals, the channels pass through carved stone grates that catch debris swept along by floodwaters, preventing blockages further downstream. These grates are designed to be easily lifted for cleaning, with carved handholds that allow workers to remove them without tools. The channel bottoms are slightly roughened to slow water velocity and reduce erosion, while still maintaining enough slope to ensure complete drainage.
Secondary channels branch off from the main arteries, running alongside walkways and around the foundations of important structures. These smaller channels, approximately one foot wide, collect water that would otherwise pool around buildings and direct it toward the main drainage system. Special attention has been paid to protecting the freshwater cisterns, with raised stone barriers and dedicated drainage channels ensuring that floodwater flows around rather than into these crucial resources. The cistern protection system includes one-way valves made from fitted wooden flaps that allow overflow water to escape during heavy rains while preventing saltwater intrusion during floods.
The channel system terminates at multiple outflow points along the settlement's perimeter, where the water empties onto the tidal flats through carved stone spillways. These spillways are positioned to take advantage of natural drainage patterns, ensuring that discharged water flows away from the settlement rather than pooling nearby. During extreme events, the combined capacity of all channels can drain the entire settlement area in less than an hour after floodwaters recede, dramatically reducing the time structures spend submerged and minimizing salt damage to buildings and stored goods. A team of channel wardens maintains the system, clearing debris after storms, repairing any damage to the stone lining, and ensuring the grates remain functional.
Benefits
The Flood Drainage Channels generate 3 Prestige, demonstrating the settlement's engineering sophistication and their mastery over the challenging tidal environment. The drainage system reduces flood damage to structures by 50%, as water is rapidly channeled away rather than being allowed to pool and soak into foundations. The protection of freshwater resources during floods grants the settlement immunity to the water contamination that typically follows storm surges, ensuring clean drinking water remains available even after severe weather events. Additionally, the rapid drainage significantly reduces the growth of mold and mildew that would otherwise plague structures in this humid environment, granting a +2 bonus on checks related to maintaining building integrity and preventing rot.