Great Dyke

The Great Dyke of Floodwake, also known as Runehildr's Bulwark after its planner and builder, is an elevated ring of earth which surrounds the run-down district of Floodwake in the City State of Styx.
Ever since its foundation as a hamlet on lowlying lakeside marshland the district had been plagued by periodic floodings that lead to rampantly spreading disease and misery among its populace.
The Temple Parliament had always considered the district a lost cause and made no effort to solve the issue so the inhabitants took matters into their own hands.
One booze filled night one particularly dastardly patron of the Whyrl's Bottom, the dwarven corsair Runehildr Úlfsdottir had what the people of Floodwake call a Schnappsidee, an idea hatched while drunk that will most likely not work out,,, except it did.
The very night the corsair had the idea she and her crew of miscreants got to work and if one is to believe the legends the Great Dyke was finished and fine by the next morning.
If the tales are true and construction happened this rapidly, there had to have been foul Witchcraft involved, says the Church of Serkatha.