1 C1 neutral
Of a waterway, harbor, or channel: to become blocked or filled with deposited silt and sediment over time.
"The old harbor has completely silted up and can no longer receive large vessels."
inseparable
silt up
C1 neutral inseparable transitive/intransitive
To become blocked or filled with silt, sediment, or fine sand, usually in a waterway.
In plain English
When mud and sand slowly fill up a river, harbor, or channel so that water can't flow properly.
What does "silt up" mean?
2 meanings, ordered from most common to least. Color-coded by CEFR level.
2 C1 neutral
To cause a waterway to become blocked with silt.
"Years of agricultural runoff have silted up the river delta."
separable
Literal vs figurative
Words literally mean
Silt (fine sand and mud) moves upward to fill a space — the process of sediment accumulation.
Actually means
When mud and sand slowly fill up a river, harbor, or channel so that water can't flow properly.
Usage tip
Primarily used in geographical, environmental, and engineering contexts. Often refers to rivers, harbors, canals, and reservoirs. Can be used transitively ('Silt has silted up the harbor') or intransitively ('The river silted up'). More common in British English.
Words that pair with "silt up"
Natural word combinations native speakers use most often.
harbor river canal reservoir estuary channel
How to conjugate "silt up"
The five tense forms you'll use most often.
Base
silt up
I/you/we/they
3rd person
silts up
he/she/it
Past simple
silted up
yesterday
Past participle
silted up
have + pp
-ing form
silting up
continuous
Hear "silt up" in the wild
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