Hydrology of Tollen

The ancient core of Tollen sits on a low rise on the north and northeast side of the Volta, across from generally swampy southern riverbanks prone to flooding, especially at high tide. Two significant rivers (the Little River and the Greywash), one minor river (the Muddy River), and two small brooks (Fat Brook and the Carnbrook) join the Volta in the area around Tollen.

They are, from east to west:

The Little River, to the west, is the largest of the Tollen rivers. It enters the city at the Tanner’s Gate, and flows through Brooklawn Inner before meeting the Volta. The Little River flows from the north, draining the line of hills northeast of Tollen. Its lower reaches are marshy and prone to flooding. The Little River and the swampy area at its mouth have long been a center for tanning, dye-making, and other water-intensive industries. In recent years, the lower Little River has been channeled and straightened, though it is still a critical waterway for industrial use.

The Muddy River, a straightened drainage-channel running north through the reclaimed marshes of the south bank, forms the border between Fenslane and Tideswell. Is the only tributary to enter Tollen from the south, its reed-choked banks flooding the low wards whenever the Volta runs high. This river spreads into many minor streams in the swampy area southwest of Tollen proper.

Fat Brook drains a small catchment of low rises east of the Little River. Fat Brook and the small unnamed trickles that feed it run along the east edge Fairgate Outer before disappearing into a culvert and crossing under the walls between Temple Gate and Guild Gate. It then flows along the eastern edge of Guildgate and Gold Street, in channels and culverts, before emptying into the Volta.

The Carnbrook runs through Nordgate, and then along the dividing line between Bridgeward and Aesganstrad. It is a small brook that vanishes into covered culverts in the city.

East of the city is the Greywash, a broad, silty, tidally-influenced tributary of the Volta, prone to flooding. A large marshlands spreads along the confluence of the Volta and the Greywash, forming a major barrier to eastward expansion of the city.