The Ndak had a few early engineering achievements, most notable of which was a canal (the name of which is no longer remembered) from a branch of the lower Aiwa twenty miles to the nearest arm of the sea. It was dug over the course of a generation by slave labor, building on the previous aborted attempts by the Ngauro to do the same. it did not actually connect to the Aiwa at the upper end; instead, a long ramp rose out of the end of the canal and descended into the Aiwa on the other side, with ships being pulled across the ramps over log rollers by - you guessed it - up to several hundred slaves pulling ropes tied to the ship.
The canal is represented on the map by a blue line, just north of the final D of "Kasadgad".
The original canal did not include the ramp, the waterway opening directly into the Aiwa, but this arrangement caused most of the river to divert down the narrow canal in a torrent sufficient to prevent upstream travel.
The canal was necessary for ships to get from the river to the sea or vice versa; the Aiwa does not empty into the sea by a single channel, but instead splits and splits again into a thousand small and shallow channels winding though the flat, swampy delta, which change course every time the river floods.