312:
509:
involves projecting the curve (graph line) formed when peak annual discharges are plotted against their respective recurrence intervals. However, in most cases the curve bends strongly, making it difficult to plot a projection accurately. This problem can be overcome by plotting the discharge and/or recurrence interval data on logarithmic graph paper. Once the plot is straightened, a line can be ruled drawn through the points. A projection can then be made by extending the line beyond the points and then reading the appropriate discharge for the recurrence interval in question.
554:, the largest ever recorded on the river, was a response to a heavy, long duration spring and summer rainfalls. Early rains saturated the soil over more than a 300,000 square miles of the upper watershed, greatly reducing infiltration and leaving soils with little or no storage capacity. As rains continued, surface depressions, wetlands, ponds, ditches, and farm fields filled with overland flow and rainwater. With no remaining capacity to hold water, additional rainfall was forced from the land into tributary channels and thence to the
343:(USGS) personnel. They wade into the stream to make the measurement or do so from a boat, bridge, or cableway over the stream. For each gaging station, a relation between gage height and streamflow is determined by simultaneous measurements of gage height and streamflow over the natural range of flows (from very low flows to floods). This relation provides the streamflow data from that station. For purposes that do not require a continuous measurement of stream flow over time,
414:
300:
558:. For more than a month, the total load of water from hundreds of tributaries exceeded the Mississippi's channel capacity, causing it to spill over its banks onto adjacent floodplains. Where the flood waters were artificially constricted by an engineered channel bordered by constructed levees and unable to spill onto large section of floodplain, the flood levels forced even higher.
137:, during both dry and rainy periods. Because of the large supply of groundwater available to the streams and the slowness of the response of groundwater to precipitation events, baseflow changes only gradually over time, and it is rarely the main cause of flooding. However, it does contribute to flooding by providing a stage onto which runoff from other sources is superimposed.
504:
For large basins, where unit hydrograph might not be useful and reliable, the magnitude and frequency method is used to calculate the probability of recurrence of large flows based on records of past years' flows. In United States, these records are maintained by the
Hydrological Division of the USGS
529:
downstream. Without streamflow, the water in a given watershed would not be able to naturally progress to its final destination in a lake or ocean. This would disrupt the ecosystem. Streamflow is one important route of water from the land to lakes and oceans. The other main routes are surface runoff
162:
runoff that begins as thin layer of water that moves very slowly (typically less than 0.25 feet per second) over the ground. Under intensive rainfall and in the absence of barriers such as rough ground, vegetation, and absorbing soil, it can mount up, rapidly reaching stream channels in minutes and
495:
using the unit hydrograph method would be difficult because in a large basin geographic conditions may vary significantly from one part of the basin to another. This is especially so with the distribution of rainfall because an individual rainstorm rarely covers the basin evenly. As a result, the
483:
This method involves building a graph in which the discharge generated by a rainstorm of a given size is plotted over time, usually hours or days. It is called the unit hydrograph method because it addresses only the runoff produced by a particular rainstorm in a specified period of time—the time
474:
For most streams especially those with a small watershed, no record of discharge is available. In that case, it is possible to make discharge estimates using the rational method or some modified version of it. However, if chronological records of discharge are available for a stream, a short term
508:
The data from each gauging station apply to the part of the basin upstream that location. Given several decades of peak annual discharges for a river, limited projections can be made to estimate the size of some large flow that has not been experienced during the period of record. The technique
487:
Once a rainfall-runoff relationship is established, then subsequent rainfall data can be used to forecast streamflow for selected storms, called standard storms. A standard rainstorm is a high intensity storm of some known magnitude and frequency. One method of unit hydrograph analysis involves
546:
of water abstraction. The flow of water assists transport downstream. A given watercourse has a maximum streamflow rate that can be accommodated by the channel that can be calculated. If the streamflow exceeds this maximum rate, as happens when an excessive amount of water is present in the
381:
Express velocity in meters per second. If the measurements were made at midstream (maximum velocity), the mean stream velocity is approximately 0.8 of the measured velocity for rough (rocky) bottom conditions and 0.9 of the measured velocity for smooth (mud, sand, smooth bedrock) bottom
391:
In the United States, streamflow gauges are funded primarily from state and local government funds. In fiscal year 2008, the USGS provided 35% of the funding for everyday operation and maintenance of gauges. Additionally, USGS uses hydrographs to study streamflow in rivers. A
104:
underground full of water by discharging water downward through their streambeds. In addition to that, the oceans stay full of water because rivers and runoff continually refreshes them. Streamflow is the main mechanism by which water moves from the land to the oceans or to
149:. Much of this water is transmitted within the soil, some of it moving within the horizons. Next to baseflow, it is the most important source of discharge for streams in forested lands. Overland flow in heavily forested areas makes negligible contributions to streamflow.
334:
are utilized. There are a variety of ways to measure the discharge of a stream or canal. A stream gauge provides continuous flow over time at one location for water resource and environmental management or other purposes. Streamflow values are better indicators than
488:
expressing the hour by hour or day by day increase in streamflow as a percentage of total runoff. Plotted on a graph, these data from the unit hydrograph for that storm, which represents the runoff added to the pre-storm baseflow.
530:(the flow of water from the land into nearby watercourses that occurs during precipitation and as a result of irrigation), flow of groundwater into surface waters, and the flow of water from constructed pipes and channels.
176:
Rivers are always moving, which is good for environment, as stagnant water does not stay fresh and inviting very long. There are many factors, both natural and human-induced, that cause rivers to continuously change:
396:
is a chart showing, most often, river stage (height of the water above an arbitrary altitude) and streamflow (amount of water, usually in cubic feet per second). Other properties, such as rainfall and
378:
Place an orange at the starting point and measure the time for it to reach the finish point with a stopwatch. Repeat this at least three times and average the measurement times.
375:
Measure a length of stream, and mark the start and finish points. The longest length without changing stream conditions is desired to obtain the most accurate measurement.
92:
that is essential for all life on Earth. A diversity of biological species, from unicellular organisms to vertebrates, depend on flowing-water systems for their
163:
causing sudden rises in discharge. The quickest response times between rainfall and streamflow occur in urbanized areas where yard drains, street gutters, and
709:
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for large streams. For a basin with an area of 5,000 square miles or more, the river system is typically gauged at five to ten places.
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collect overland flow and route it to streams straightaway. Runoff velocities in storm sewer pipes can reach 10 to 15 feet per second.
326:
Streamflow is measured as an amount of water passing through a specific point over time. The units used in the United States are
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Streamflow confers on society both benefits and hazards. Runoff downstream is a means to collect water for storage in
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117:
Stream discharge is derived from four sources: channel precipitation, overland flow, interflow, and groundwater.
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enters the streambed where the channel intersects the water table, providing a steady supply of water, termed
125:
is the moisture falling directly on the water surface, and in most streams, it adds very little to discharge.
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basin does not respond as a unit to a given storm, making it difficult to construct a reliable hydrograph.
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435:
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is water that infiltrates the soil and then moves laterally to the stream channel in the zone above the
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710:"How do I interpret gage height and streamflow values? — USGS Water Data for the Nation Help System"
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of conditions along the whole river. Measurements of streamflow are made about every six weeks by
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are major aquatic landscapes for all manners of plants and animals. Rivers even help keep the
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velocity profilers can be used. For small streams—a few meters wide or smaller—
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56:. Water flowing in channels comes from surface runoff from adjacent hillslopes, from
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One informal method that provides an approximation of the stream flow termed the
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watercourse, the channel cannot handle all the water, and flooding occurs.
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forecast of discharge can be made for a given rainstorm using a hydrograph.
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Construction, removal, and sedimentation of reservoirs and stormwater
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occurs when the volume of water exceeds the capacity of the channel.
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796:"Streamflow - Environmental Science: In Context | Encyclopedia.com"
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taken for a river to rise, peak, and fall in response to a storm.
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In dry regions, cultivated, and urbanized areas, overland flow or
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flow out of the ground, and from water discharged from pipes. The
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672:"Streamflow - The Water Cycle, from USGS Water-Science School"
623:"Streamflow - The Water Cycle, from USGS Water-Science School"
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that alter rates of erosion, infiltration, overland flow, or
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Runoff of water in channels is responsible for transport of
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cubic meters per second measured daily at
Vicksburg, MS, US.
158:
is usually a major source of streamflow. Overland flow is a
352:
211:
539:
295:
Stream gauge § Streamflow discharge measurement
757:Delaware River Basin Commission. West Trenton, NJ.
244:
River-flow regulation for hydropower and navigation
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Surface-water withdrawals and transbasin diversions
759:"Who Pays for the Maintenance of Gaging-Stations?"
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46:component, the movement of water from the land to
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852:
64:of water flowing in a channel is measured using
204:Ground-water recharge from surface-water bodies
648:Landscape Planning: Environmental Applications
442:. Unsourced material may be challenged and
172:Mechanisms that cause changes in streamflow
72:. The record of flow over time is called a
16:Flow of water in streams and other channels
772:"USGS WaterWatch -- Streamflow conditions"
533:
83:
478:
462:Learn how and when to remove this message
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696:"MISSISSIPPI RIVER AT VICKSBURG, MS"
440:adding citations to reliable sources
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201:Ground-water discharge from aquifers
88:Streams play a critical role in the
303:Mississippi River streamflow in log
260:Drainage or restoration of wetlands
13:
192:from soil and surface-water bodies
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872:
491:To forecast the flows in a large
186:Runoff from rainfall and snowmelt
646:Marsh, William M. (2010-07-06).
412:
400:parameters can also be plotted.
358:
330:, while in most other countries
38:, and is a major element of the
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513:Relationship to the environment
341:United States Geological Survey
316:United States Geological Survey
844:"The Water Cycle: Streamflow."
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500:Magnitude and frequency method
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820:"The Great USA Flood of 1993"
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318:stream gaging station on the
552:1993 Mississippi river flood
220:Formation or dissipation of
50:, the other component being
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573:List of rivers by discharge
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107:basins of interior drainage
68:or can be estimated by the
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747:"10. Measuring Discharge."
732:R.G. Wetzel, G.E. Likens:
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253:Stream channelization and
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588:Runoff model (reservoir)
236:Human-induced mechanisms
714:help.waterdata.usgs.gov
534:Relationship to society
332:cubic meters per second
84:Role in the water cycle
568:Hydrological modelling
479:Unit hydrograph method
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745:U.S. Forest Service.
734:Limnological Analyses
650:(5 ed.). Wiley.
328:cubic feet per second
322:at Lac qui Parle Dam.
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800:www.encyclopedia.com
436:improve this section
96:and food resources.
842:USGS, Atlanta, GA.
776:waterwatch.usgs.gov
347:meters or acoustic
824:www.nwrfc.noaa.gov
355:may be installed.
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272:evapotranspiration
181:Natural mechanisms
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452:February 2024
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421:This section
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434:Please help
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369:float method
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268:urbanization
257:construction
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165:storm sewers
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42:. It is one
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761:2009-04-30.
404:Forecasting
382:conditions.
337:gage height
289:Measurement
190:Evaporation
147:water table
131:Groundwater
58:groundwater
48:waterbodies
40:water cycle
829:2016-05-06
805:2016-05-06
781:2016-05-07
719:2016-05-06
681:2016-05-07
632:2016-05-06
609:References
593:Stream bed
394:hydrograph
387:Monitoring
293:See also:
283:Irrigation
277:Wastewater
230:permafrost
226:snowfields
160:stormwater
74:hydrograph
34:and other
20:Streamflow
861:Hydrology
527:pollution
523:nutrients
423:does not
143:Interflow
62:discharge
855:Category
562:See also
519:sediment
279:outfalls
264:Land use
222:glaciers
216:wetlands
135:baseflow
121:Channel
102:aquifers
78:Flooding
36:channels
444:removed
429:sources
349:Doppler
345:current
113:Sources
94:habitat
32:streams
654:
525:, and
228:, and
98:Rivers
44:runoff
353:weirs
255:levee
212:lakes
28:water
22:, or
652:ISBN
550:The
542:for
540:dams
427:any
425:cite
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214:and
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367:or
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