Streamflow

Streamflow

Streamflow, or channel runoff, is the flow of water in streams, rivers, and other channels, and is a major element of the water cycle. It is one component of the runoff of water from the land to waterbodies, the other component being surface runoff. Water flowing in channels comes from surface runoff from adjacent hillslopes, from groundwater flow out of the ground, and from water discharged from pipes. The discharge of water flowing in a channel is measured using stream gauges or can be estimated by the Manning equation. The record of flow over time is called a hydrograph. Flooding occurs when the volume of water exceeds the capacity of the channel.

Contents

Role in the water cycle

Streamflow is the main mechanism by which water moves from the land to the oceans or to basins of interior drainage.

Measurement

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. For purposes that do not require a continuous measurement of stream flow over time, current meters or acoustic Doppler velocity profilers can be used. For small streams — a few meters wide or smaller — weirs may be installed. One informal method that provides an approximation of the stream flow termed the Orange Method or Float Method is:

  1. 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.
  2. 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.
  3. 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 conditions.[1][2]

Flow monitoring in the United States

In the United States, streamflow gauges are funded primarily from state and local government funds. In Fiscal Year 2008 the United States Geological Survey (USGS) provided 35 percent of the funding for everyday operation and maintenance of gauges.[3]

Relationship to the environment

Runoff of water in channels is responsible for transport of sediment, nutrients, and pollution downstream.

Relationship to society

Streamflow confers on society both benefits and hazards. Runoff downstream is a means to collect water for storage in dams for power generation of water abstraction. The flow of water assists transport downstream. When the flow of water exceeds the capacity of the channel, flooding occurs.

See also

References

  1. ^ R.G. Wetzel, G.E. Likens: Limnological Analyses, pp. 62–63.
  2. ^ U.S. Forest Service. "10. Measuring Discharge."
  3. ^ Delaware River Basin Commission. West Trenton, NJ. "Who Pays for the Maintenance of Gaging-Stations?" 2009-04-30.



Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • streamflow — the discharge that occurs in a natural channel; usually used to describe the discharge in a surface stream. The term streamflow is more general than the term runoff, as streamflow may be applied to discharge whether or not it is affected by… …   Dictionary of ichthyology

  • streamflow — /streem floh /, n. the water that flows in a specific stream site, esp. its volume and rate of flow. [STREAM + FLOW] * * * …   Universalium

  • streamflow — noun The runoff of surface water through a channel …   Wiktionary

  • streamflow — ˈ ̷ ̷ˌ ̷ ̷ noun : water flowing in a stream channel; specifically : the velocity and volume of such water …   Useful english dictionary

  • Natural streamflow —   The rate of flow of water past a given point of an uncontrolled stream or regulated streamflow adjusted to eliminate the effects of reservoir storage or upstream diversions at a set time interval.   U.S. Dept. of Energy, Energy Information… …   Energy terms

  • Maximum streamflow —   The maximum rate of water flow past a given point during a specified period.   U.S. Dept. of Energy, Energy Information Administration s Energy Glossary …   Energy terms

  • Median streamflow —   The middle rate of flow of water past a given point for which there have been several greater and lesser rates of flow occurring during a specified period.   U.S. Dept. of Energy, Energy Information Administration s Energy Glossary …   Energy terms

  • Minimum streamflow —   The lowest rate of flow of water past a given point during a specified period.   U.S. Dept. of Energy, Energy Information Administration s Energy Glossary …   Energy terms

  • Regulated streamflow —   The rate of flow past a given point during a specified period that is controlled by reservoir water release operation.   U.S. Dept. of Energy, Energy Information Administration s Energy Glossary …   Energy terms

  • Stream gauge — A stream gauge, or stream gage, refers to a site along a stream where measurements of volumetric discharge (flow) are made. Measurement of DischargeAutomated direct measurement of streamflow discharge is difficult at present. In place of the… …   Wikipedia

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”