rivulet

A rivulet is a small natural stream, typically smaller than a brook or creek. It is a minor watercourse that carries surface water along a distinct channel, though some rivulets are intermittent and flow only after rainfall, while others are perennial in wetter regions or certain seasons. They arise from precipitation, snowmelt, or groundwater discharge, and collect runoff from a local catchment before draining into a larger river, a lake, wetland, or another stream.

Morphology and movement vary with climate and terrain. Rivulets are usually narrow and shallow, with a gravelly or silty bed. The channel may be straight or winding, and can become braided in conditions of high sediment supply or fluctuating flows. Erosion and deposition along a rivulet can carve small valleys and create riffles, pools, and pockets of vegetation along the banks.

Hydrology and ecology. Rivulets contribute to landscape hydrology by delivering water during rain events and, in some climates, sustaining baseflow in connected networks. They provide habitat for aquatic invertebrates, algae, and early-stage aquatic plants; their banks support moisture-loving vegetation and small wildlife. Their course can shift over time, and they may dry up during droughts or be reactivated after rainfall.

Regional usage and terminology. The term rivulet is often used to describe a very small stream, especially in literary or poetic contexts. In some regions rivulet may be used interchangeably with brook, creek, or stream, while in others it denotes a distinctly minor watercourse. Etymology traces to Middle English rivule, from Old French rivule, a diminutive related to rivier or river.