60+ River Features For Fantasy Worldbuilding31 min read

Springs and streams, rivers and rapids! Welcome back, Outlander, to the 4th entry in Mythic Ecology, my series on how learning real-world landscape features can enrich our fantasy worldbuilding and storytelling. In this post I return to my minimalist framework for Dungeon Masters, Game Masters, fiction writers, and similar worldbuilders to merge the realms of general myth and geomorphology. Last week we looked at lakes. As I resume my journey sketching a framework for designing Yridia, my unique D&D 5e fantasy world, let’s learn some river terms, with a visual guide!

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Let’s revisit my minimalist framework for my worldbuilding, which will unfold gradually. The six archetype tags with which I will flag all the various real-world land features in my Mythic Ecology Series:

1. Settlements: habitable regions of either Work or Play, Familiar or Exotic, offering diverse narrative functions: a Day in the Life, Home Base, Personal Reasons, Gathering Supplies. Can subvert tropes with Ruins or Escape.
2. Omens: sensational, temporal, or particularly pointed features that offer narrative functions of forshadowing, and good or evil portents. Can subvert tropes with a Wild Goose Chase.
3. Overlooks: sites of magnitude and grandeur, living monuments which can function narratively for finding resolve, invoking spirits, or as a Call to Adventure. Can subvert tropes with Dread or Betrayal.
4. Passageways: transitional journeylands, including magical portals, functioning narratively for initiation and return, thresholds and tests, shortcuts and setbacks.
5. Abyss: a void or confined space presenting scarcity or temptation, desperation and danger. Can subvert tropes with a Timely Rescue or Secret Refuge.
6. Battlegrounds: sites fit for epic, sprawling encounters and climax conflicts. Can subvert tropes with Alternative Solutions.

Feel free to submit your own ideas, or draw outside the lines. Alright, let’s see how rivers fit in.

A “river” refers to a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake, or another river, sometimes drying before arrival. It arises as precipitation collects in drainage basins from surface runoff, groundwater recharge, springs, ice and snowmelt.

Terms for small rivers include: stream, creek, brook, rivulet, and rill. Usually, but not always, a river appears larger than a “creek”.

A rivers originates at a source or sources, follows a course, and ends at a mouth or mouths. Usually it lays within a channel, composed of a streambed between banks. Larger rivers can have a flooplain, where flood-waters overfill the channel, potentially in a wide area. Rivers tend to flow down mountains, through valleys or depressions, and along plains, and can create canyons or gorges.

Seepage Spring / Seep / Flush – moist or wet spot where water, normally groundwater, reaches the surface from an underground aquifer.

Fracture Spring – discharge from faults, joints, or fissures, where springs follow a natural course of voids or weaknesses in bedrock.

Tubular Spring – water flows from underground caverns.

Headwaters – the part of the river closest to its source.

Brook – a stream smaller than a creek, usually fed by a spring or seep. Usually small and shallow, easily forded.
[Passageways]

Creek – regionally either (a) small to medium natural stream, navigable but sometimes intermittent; or (b) a tidal inlet like a salt marsh or mangrove swamp, or tidal stream of seawater between enclosed and drained former salt marshes or swamps.
[Passageways]

Runnel – a linear and narrow channel in the ground for liquid to flow through, usually between the ridges or bars of shoreline beach or river floodplain.
[Omens, Passageways, Abyss]

Tributary / Affluent / Branch / Fork – a stream or river which flows into larger stream, main stem river, or lake.
[Settlements, Passageways, Battlegrounds]

Confluences – joined tributaries.
[Settlements, Omens, Passageways, Abyss]

Distributary – opposite of a tributary, streams branching off into forks and flowing away, creating river deltas.
[Omens, Battlegrounds]

Chemistry and sediment can affect color in interesting ways; these appear particularly in the Amazon.

Clearwater River – has low conductivity and dissolved solids, neutral to slightly acidic pH, and very clear with a greenish hue. Often has fast-flowing section.
[Omens, Passageways]

Blackwater River – also known as black mud rivers, these have slow-moving channel flowing through swamp, with dark stain from decaying vegetation. Lower nutrients and higher ionic concentrations than rainwater.
[Omens, Passageways]

Whitewater River – rivers with high levels of suspended sediments, neutral pH, high conductivity, and pale muddy color.
[Omens, Passageways]

Alluvial – self-formed in unconsolidated or weakly consolidated sediments. They erode their banks and deposit material on bars and floodplains.
[Omens, Passageways]

Bedrock – form when a stream cuts down through its sediment into the underlying bedrock.
[Omens, Passageways]

Mixed – streams which go through both patches of bedrock and patches of deep alluvial cover.
[Omens, Passageways]

Many factors affect in channel type development: stream gradient, substrate composition, riparian vegetation, sediment supply, and discharge. Large woody debris may strongly influence it as well.

Anastomosed River – interconnected multithreaded channel belts on alluvial plains, with banks held together by dense vegetation.
[Settlements, Omens, Passageways, Battlegrounds]

Braided Rivers – unstable multithreaded streams that form in tectonically active areas and have a high gradient and larger sedimentary load than the discharge of the river.
[Omens, Passageways]

Meandering Rivers / Single-Thread Sinuous Rivers – singlethreaded streams of sinuous path in a usually low-gradient plain toward the end of a river system.
[Omens, Passageways]

Straight River – a rare, unstable, and constrained stream with mobile alternate bars and gravel environments.
[Omens, Passageways]

Riffle-Pools – composed of migrating pools and transverse bars called riffles. Gradients of less than 1-2 percent. Can include all low gradient channel forms too.
[Passageways, Abyss]

Step-Pools – composed of channel-spanning pools and boulder/cobble steps that cause subcritical flow in the pool and supercritical flow over the steps. Gradients of 5-20 percent.
[Passageways, Abyss]

Rapids / Plane Bed – section of a river with a relatively deep river bed, increasing the water’s velocity and turbulence. Lacks distinct pools and bars, but commonly has stone cells or clusters. Gradients of 1-5 percent, with “whitewater”.
[Omens, Passageways, Abyss]

Cascades – where boulders and cobbles dominate a steep channel, and channel spanning pools do not exist. Gradients 10-15 percent. Often has pocket pools.
[Omens, Passageways, Abyss]

Arroyo – a dry creek or stream bed with flow after rain.
[Omens, Passageways, Abyss]

Ephemeral / Intermittent River – only flows occasionally, sometimes dry for several years at a time.
[Omens, Passageways, Abyss]

Tidal River – a river with flow and level influenced by tides.
[Omens, Passageways, Abyss]

Wadi – river valley, especially a dry riverbed that contains water only during times of heavy rain.
[Omens, Passageways, Abyss]

Winterbourne – a stream which dries out in the summer months.
[Omens, Passageways, Abyss]

Geyser – a spring with intermittent, turbulent discharge of water and steam.
[Omens, Passageways, Abyss]

Hot Spring – a spring produced by geothermal-heated groundwater rising from the Earth’s crust.
[Omens, Passageways, Abyss]

Karst Spring – a spring usually the end of a cave system where a river cave reaches the Earth’s surface, which often has a very large discharge.
[Omens, Overlooks, Passageways, Abyss]

Mineral Spring – spring that produces water containing minerals like salts, or other dissolved substances like sulfur compounds or gases, that alter taste or give a purported therapeutic value.
[Settlements, Omens, Overlooks, Passageways]

Rhythmic Spring / Ebb and Flow Spring / Periodic Spring / Intermittent Spring – an uncommon cold water spring from which waterflow varies or stops entirely, but over a regular time-scale of minutes to hours.
[Omens, Passageways]

Alluvial Fan – fan- or cone-shaped deposit of sediment crossed and built up by streams.
[Omens, Overlooks, Battlegrounds]

Crevasse Splay – sediment deposited on a floodplain by a stream which breaks its levees.
[Omens, Overlooks, Battlegrounds]

Outwash Fan – a fan-shaped body of sediments deposited by braided streams from a melting glacier.
[Omens, Overlooks, Battlegrounds]

Kame Delta / Ice-Contact Delta / Morainic Delta – glacial landform made by a stream of meltwater flowing through or around a glacier and depositing stratified sediment deposits as it enters a proglacial lake, creating a triangular delta.
[Omens, Overlooks, Battlegrounds]

River Delta – silt deposition landform at the mouth of a river.
[Settlements, Omens, Passageways, Battlegrounds]

Ait / Eyot / Fluvial Island – a river island. A holm also denotes an island in a lake, river, or estuary.
[Omens, Abyss]

Anabranch – stream section that diverts from the main channel and rejoins downstream.
[Settlements, Omens, Passageways, Battlegrounds]

Chalk Stream – streams flowing through chalk hills towards the sea, typically wide and shallow, alkaline and clear.
[Omens, Passageways]

Cut Bank – outside bank of a water channel, continually undergoing erosion. Opposes a point bar, and fits with a meander.
[Omens, Overlooks, Passageways]

Eddy – a circular movement of water, counter to a main current, causing a small whirlpool.
[Omens, Passageways]

Entrenched / Incised / Enclosed / Ingrown Meanders – meanders of a stream or river that has cut its bed down into the bedrock.
[Omens, Overlooks, Passageways, Abyss, Battlegrounds]

Esker – long, winding ridge of stratified sand and gravel associated with former glaciers.
[Omens, Passageways, Battlegrounds]

Estuary – a partially enclosed coastal body of brackish water with one or more streams flowing into it, with a free connection to the open sea.
[Settlements, Omens, Passageways, Battlegrounds]

Exhumed River Channel – a ridge of sandstone that remains after the softer flood plain mudstone erodes away.
[Omens, Passageways, Battlegrounds]

Floodplain – land adjacent to a stream which floods during periods of high discharge.
[Settlements, Omens, Passageways, Battlegrounds]

Fluvial Terrace – elongated terraces that flank the sides of floodplains and river valleys.
[Settlements, Omens, Overlooks]

Knickpoint – point on a stream’s profile with a sudden change in stream gradient.
[Omens, Overlooks]

Misfit Stream – a river too large or too small to have eroded the valley or cave passage in which it flows. Also applies with stream meanders not proportional in size to the meanders of the valley or meander scars cut into valley walls. Includes overfit and underfit streams.
[Omens, Passageways]

Point Bar – a depositional feature of alluvium that accumulates on the inside bend of streams and rivers below the slip-off slope. Opposes a cut bank, and fits with a meander.
[Omens, Overlooks, Abyss]

Riparian Zone/Area – the interface between land and stream.
[Settlements, Omens, Passageways]

Rock-Cut Basin – cylindrical depressions cut into stream or river beds.
[Omens, Overlooks, Passageways, Abyss]

Shut-In – rock formation where streams carve through a mountain range, causing a complex of pools, rivulets, rapids, and plunge pools. Usually confined to a narrow valley or canyon, with a river valley widening out both above and below.
[Omens, Overlooks, Passageways, Abyss]

Stream Pool – a stretch of a river or stream in which the water is relatively deep and slow moving.
[Omens, Passageways]

Subterranean River – rivers flowing underground or in caves, usually with limestone geology, or subglacial.
[Omens, Passageways, Abyss]

Thalweg – line of lowest elevation in a watercourse or valley.
[Omens, Passageways]

Torrent – a stream with a high seasonal variation in its flow.
[Omens, Passageways]

Towhead – exposed land within a river, usually a small islet or sandbar with a thicket of trees
[Omens, Abyss]

Waterfall – place where water flows over a vertical drop in the course of a river.
[Omens, Overlooks, Passageways]

Yazoo Stream – tributary system that runs parallel to, and within the floodplain of a larger river for considerable distance.
[Omens, Passageways]

I hope you enjoyed this fourth entry in my Mythic Ecology series! I look forward to continuing with it, I have some greater ambitions for developing this series into worldbuilding web tools. Give this a share if you liked it, and let me know in the comments if you have any feedback. I publish new posts on Tuesdays. In the meantime, I post original D&D memes and writing updates daily over on my site’s Facebook Page. Also, if you want to keep up-to-date on all my posts, check out my Newsletter Sign-Up to receive email notifications when I release new posts. A big thanks as always to my Patrons on Patreon, helping keep this project going: Anthony, Chris, Eric & Jones, Geoff, Jason, Rudy, and Tom. Thanks for your support!