The monitoring network within this area

Hydrionis holds 523 values from 2 gauges within it. Discharge is a property of a gauge and its reach, not of this drainage area, so this page reports the network and its records rather than a single figure.

Gauges

523

Values held

1899–2026

Record spans

Gauges within the Upper Roanoke huc8 subbasin

2 monitoring points, positioned as the publisher records them.

Flood peaks, as measured

This gauge's flood record, as measured. Unlike a daily mean it is the discharge at the moment the river was highest, which is the figure flood frequency analysis is built on.

Largest measured flow of each year at ROANOKE RIVER AT ROANOKE, VA

The highest instantaneous discharge the publisher recorded in each year — a flood peak as measured, not a daily average of one. 1899–2025.

Show relevant events (1 event)Shading marks when something was recorded, not what caused the line.

Published by the gauge's own operator from its sub-daily record; Hydrionis stores the figure rather than recomputing it. A year the gauge did not cover produces no value rather than a low one, and the gaps are stated below the chart. A peak is a property of this gauge and its reach: a larger flood upstream or downstream of it is not in this series.

What the shaded periods are (1 event)

A shaded period marks when something was recorded, not what caused the shape of the line. Where the two coincide, they coincided.

Documented record — A documented event, compiled from cited sources after it happened. The dates are as good as the record, which for older events can mean the month rather than the day.

Event	Type	Period	Standing	Authority
Hurricane Katrina water and sanitation collapse	Flood	2005-08-29 – 2005-09-30	Documented record	Compiled record

Not shown on this chart

The 1976 drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
The 2022 drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Yorkshire drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Cantareira water crisis, São Paulo — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Cape Town Day Zero — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
European drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.

View the data behind this chart

Underlying data
Period	ROANOKE RIVER AT ROANOKE, VA (m³/s)
1899	311
1900	143
1901	538
1902	433
1903	289
1904	82.1
1905	419
1907	281
1908	334
1910	266
1911	86.1
1912	254
1913	258
1914	78.7
1915	228
1917	182
1918	182
1919	190
1920	121
1921	399
1923	156
1924	272
1925	36.8
1926	63.4
1928	640
1929	147
1931	98.3
1932	63.4
1934	186
1935	323
1936	294
1937	260
1939	240
1940	646
1941	111
1942	163
1943	166
1944	135
1945	428
1946	153
1947	169
1948	337
1950	197
1952	186
1953	204
1954	135
1956	121
1957	252
1958	163
1959	422
1960	147
1961	113
1962	239
1964	110
1965	161
1966	157
1967	311
1968	110
1969	150
1971	145
1972	716
1973	368
1974	134
1975	351
1976	110
1977	311
1978	682
1979	337
1980	260
1981	83.0
1982	186
1983	377
1984	193
1985	323
1987	422
1988	41.3
1989	337
1991	178
1992	623
1993	311
1995	306
1996	408
1998	365
1999	102
2000	159
2001	90.9
2002	92.0
2003	493
2004	609
2005	136
2006	357
2008	78.4
2009	71.6
2011	136
2013	453
2014	114
2015	462
2017	292
2018	289
2020	484
2022	138
2023	153
2024	360
2025	0

About this series

Everything below is a property of the data rather than a rating of it. There is deliberately no single confidence score: how much a gap matters depends on what you are about to do with the series, and only you know that.

Source	United States Geological Survey — National Water Information System · US Government work — public domain
How the values came to exist	Measured
Period held	1899–2025
Completeness	81.9% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	23 separate periods inside 1899–2025 hold no value. They are drawn as breaks in the line and are never interpolated across.
Continuity	The record begins in 1899 and is not continuous from it: 127 years separate the first value from the last, and 82% of the years between them are held. The span is not the record.
Last read from the publisher	2026-08-31
Redistribution	Permitted by the upstream licences
Commercial reuse	Permitted by the upstream licences. No Hydrionis access tier can widen this.
Methodology	How this was produced

How much of the rain came back out

A discharge in cubic metres per second cannot be compared with anything: the larger number may only mean the larger catchment. Divided by the area draining to the gauge it becomes a depth of water over that land, which answers a question a reader already has — of the rain that fell here, how much came back out as river?

Water leaving the catchment above ROANOKE RIVER AT ROANOKE, VA, as a depth

The year's flow spread over the land draining to this gauge, in millimetres — the same unit rainfall is measured in. 1900–2025.

Show relevant events (1 event)Shading marks when something was recorded, not what caused the line.

Computed by Hydrionis from the published annual mean flow and the catchment area the station's own publisher states. It is not a water balance: the difference between rainfall and runoff is not evaporation alone but also change in groundwater storage, water abstracted and taken elsewhere, and water imported by transfer schemes — which is why a catchment can yield more runoff than the rain that fell on it without anything being measured wrongly. A different area figure rescales every value here by the ratio between them.

What the shaded periods are (1 event)

A shaded period marks when something was recorded, not what caused the shape of the line. Where the two coincide, they coincided.

Documented record — A documented event, compiled from cited sources after it happened. The dates are as good as the record, which for older events can mean the month rather than the day.

Event	Type	Period	Standing	Authority
Hurricane Katrina water and sanitation collapse	Flood	2005-08-29 – 2005-09-30	Documented record	Compiled record

Not shown on this chart

The 1976 drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
The 2022 drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Yorkshire drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Cantareira water crisis, São Paulo — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
Cape Town Day Zero — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.
European drought — This event’s area does not contain this chart’s subject. Sharing a country is not sharing an event, so it is not drawn.

View the data behind this chart

Underlying data
Period	ROANOKE RIVER AT ROANOKE, VA (mm)
1900	407
1901	778
1902	408
1903	508
1904	209
1905	397
1906	404
1907	462
1908	461
1909	391
1910	300
1911	325
1912	468
1913	309
1914	370
1915	430
1916	313
1917	250
1918	490
1919	346
1920	262
1921	284
1922	352
1923	270
1924	386
1925	156
1926	223
1929	518
1930	135
1931	178
1932	323
1933	266
1934	231
1935	385
1936	464
1937	474
1938	284
1939	246
1940	416
1941	156
1942	253
1943	301
1944	268
1945	301
1946	312
1947	371
1948	499
1949	513
1950	383
1951	313
1952	325
1953	263
1954	200
1955	295
1956	218
1957	403
1958	371
1959	284
1960	355
1961	311
1962	347
1963	189
1964	253
1965	235
1966	236
1967	280
1968	266
1969	233
1970	201
1971	375
1972	538
1973	447
1974	261
1975	343
1976	285
1977	278
1978	456
1979	472
1980	317
1981	102
1982	319
1983	427
1984	326
1985	319
1986	230
1987	503
1988	148
1989	400
1990	400
1991	317
1992	401
1993	412
1994	409
1995	283
1996	490
1997	266
1998	472
1999	161
2000	183
2001	173
2002	160
2003	599
2004	431
2005	280
2006	270
2007	208
2008	113
2009	375
2010	336
2011	313
2012	195
2013	452
2014	323
2015	435
2016	396
2017	331
2018	535
2019	433
2020	689
2021	348
2022	288
2023	263
2024	247
2025	267

About this series

Source	United States Geological Survey — National Water Information System · US Government work — public domain
How the values came to exist	Derived Computed by Hydrionis
Period held	1900–2025
Completeness	98.4% of the periods in that span are held. Gaps are drawn as breaks and never interpolated.
Known gaps	One period inside 1900–2025 holds no value: 1927 to 1928, 2 years with no reading. It is drawn as a break in the line and is never interpolated across.
Continuity	The record begins in 1900 and is not continuous from it: 126 years separate the first value from the last, and 98% of the years between them are held. The span is not the record.
Last read from the publisher	2026-08-24
Redistribution	Permitted by the upstream licences
Commercial reuse	Permitted by the upstream licences. No Hydrionis access tier can widen this.
Methodology	How this was produced

Every gauge Hydrionis holds within this area

Gauges within the Upper Roanoke and what each holds
Gauge	Measures	Values	Record
ROANOKE RIVER AT ROANOKE, VA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow	288	1899–2026
ROANOKE RIVER AT NIAGARA, VA	burned area within 50 km, catchment area, annual maximum river flow, mean river flow	235	1926–2026

How these gauges were attached to this water

Assigned by the publisher to a numbered basin Every gauge here is assigned to this drainage area by its own publisher, which issues the area an official code — 03010101. A drainage area is not a river: it contains the tributaries as well as the main channel, and a gauge in it may be on any of them.

What each gauge’s link to this water rests on
Gauge	Evidence	Established
ROANOKE RIVER AT ROANOKE, VA	Stated by the publisher — USGS site service, huc_cd field — https://waterservices.usgs.gov/nwis/site/ ; named from the USGS Watershed Boundary Dataset 8-digit HU (Subbasin) layer — https://hydro.nationalmap.gov/arcgis/rest/services/wbd/MapServer/4	2026-08-26
ROANOKE RIVER AT NIAGARA, VA	Stated by the publisher — USGS site service, huc_cd field — https://waterservices.usgs.gov/nwis/site/ ; named from the USGS Watershed Boundary Dataset 8-digit HU (Subbasin) layer — https://hydro.nationalmap.gov/arcgis/rest/services/wbd/MapServer/4	2026-08-26

What this record holds

Hydrionis decides which waters get a page, and which of those are offered to search, from what is actually held rather than from how the page reads. Five signals are counted; this record has 3 of them, which makes it a full profile.

Information-gain signals held for this water body
Signal	Held	Counts
Gauges holding a real record	2	no
Years spanned	128	yes, 20 or more
Values held	523	no
Distinct measurements	4	yes, 2 or more
Publishers measuring it	2	yes, 2 or more
Official identifiers	1	recorded, not counted

Use this data

Machine-readable JSON /api/v1/observations/by-subject/gauge-usgs-02055000.json
How to cite this, and who you must credit
How these figures were produced
Request this at a different scale, format or geography

No bulk download is offered here, which is a licence position rather than a product one: at least one contributing publisher does not permit redistribution. The values can be read on the page, cited, and pointed to at source.

Attribution and citation

Suggested citation for Hydrionis

Hydrionis (2026), Upper Roanoke gauge records, accessed 2026-09-02, hydrionis.com/waters/united-states-upper-roanoke/

Cite Hydrionis where you rely on values Hydrionis computed, on the method that produced them, or on the compilation itself. The underlying measurements remain the publishers’ and their attribution requirements apply to you directly.

Recommended, not required. Hydrionis does not claim rights over unmodified public data it relayed, and doing arithmetic on somebody else’s measurements does not make them Hydrionis’s. Cite the version and the access date: the Upper Roanoke gauge records changes as publishers release and as methods are revised, and a citation without both cannot be checked later. Full guidance is on cite and reuse.

None of the contributing licences requires attribution. Crediting the publishers is still good practice and they are listed above.

Where these figures come from

MeasuredHigh confidence2025-02-16

Source: USGS — National Water Information System, USGS site 02055000, annual peak streamflow. Licence: Open.

Method: The instantaneous maximum discharge of each water year as published by USGS, dated to the day it occurred. One value per October-to-September water year; where the publisher lists both a systematic and a historic peak for a year, the larger is the annual maximum. Values the publisher marks as maximum daily averages are not held here, because they are not instantaneous peaks. Values marked as bounded rather than measured are held as censored observations carrying the bound. Cubic feet per second are converted to cubic metres per second and the publisher unit is recorded alongside.

Rating curves are extrapolated at extreme discharges, so the largest values in a peak series carry the largest measurement uncertainty. Data from the U.S. Geological Survey National Water Information System, a work of the United States government and therefore in the public domain.

Retrieved 31 August 2026.