why can't q river flow more than 10 times its width without changing course

Why does the width of a river increase as it flows downstream?

River Flow Regimes. The temporal patterns of high and low flows are referred to collectively as a river’s flow regime. The flow regime plays a key role in regulating geomorphic processes that shape river channels and floodplains, ecological processes that govern the life history of aquatic organisms, and is a major determinant of the biodiversity found in river ecosystems.

How does the cross profile of a river change?

Cubic feet per second (cfs) is one of the key indicators of river or creek conditions. The mathematical formula is: river width x depth x speed (flow and gradient) = cfs. Cfs readings …

How to determine the flow regime of rivers?

 · West Branch Susquehanna River, Pennsylvania Credit: Wikipedia. If you read our discussion on the role the oceans play in the water cycle, you know that evaporation from the …

What are the three ways in which a river changes over time?

Hydrometry, a science distinct and complementary to hydrology (science of water in its natural environment) and hydraulics (physics of flows), is the discipline that seeks to measure river …

What happens when a river is widened?

River management The river channel may be widened or deepened allowing it to carry more water. A river channel may be straightened so that water can travel faster along the course. The channel course of the river can also be altered, diverting floodwaters away from settlements.

What causes a river to change course?

Due to constant deposition of river sediments on the slower side and the vast amount of erosion that takes place on the faster side. This process keeps on continuing till the curves get sharpened, so that river cuts through the curve and forms another path and thus river changes its course.

What factors affect flow rate of river?

The velocity of a river is determined by many factors, including the shape of its channel, the gradient of the slope that the river moves along, the volume of water that the river carries and the amount of friction caused by rough edges within the riverbed.

How does the width of a river change?

The slope of a river decreases as it flows progressively downstream. Gravitational force is stronger uphill, but gentle in the lower course. The water tends to flow slowly due to higher water friction, hence the width increases. Towards the mouth, the gradient is lower, enabling water to flow on a wide surface area.

Do some rivers change their course?

We know that rivers are natural water bodies that flow from one place to another place. At a particular interval of time, rivers change their course and move in different directions due to the rocks present at the shores.

How can you change the flow of a river?

Human actions that can change streamflow patterns include dam building, stream diversion, pumping of shallow groundwater, and covering the landscape with impervious surfaces such as pavement and roofs. Changes in climate also can alter flow by altering timing and amount of precipitation.

What affects the flow of water?

Fluid flow in pipes is affected by many different factors: The viscosity, density, and velocity of the fluid. Changes in the fluid temperature will change the viscosity & density of the fluid. The length, inner diameter, and in the case of turbulent flow, the internal roughness of the pipe.

What changes the speed of a river?

Factors that affect the speed of a river include the slope gradient, the roughness of the channel, and tides. Rivers tend to flow from a higher elevation to a lower elevation.

What makes a river flow faster?

Generally a narrower, more circular river channel allows faster flow of water. Broader flat channels tend to slow a river down. 2. Smoother channels also allow faster flow of water; rougher channels slow water flow.

Why did the river become wider than it was in the past?

It's well known that rivers increase in size as they transport water from their source in their headwaters to the mouth. The river channel becomes wider and deeper and as a result its cross-sectional area increases. We can also observe along the river's course an increase in both quantity of water and bedload.

Why does width and depth increase downstream?

Both width and depth increase downstream because discharge increases downstream. As discharge increases the cross sectional shape will change, with the stream becoming deeper and wider.

Why do river channels in the lower course tend to be wider than the upper course?

Erosion is the most dominant action of river in the upper course. In the lower course, the river moving down stream across a broad, level plain is loaded with debris brought down from its upper and middle courses. Therefore the river channels are wider in the lower course compared to the upper course.

Why do rivers have variability?

The vast majority of rivers are known to exhibit considerable variability in flow over time because inputs from the watershed, in the form of rain events, snowmelt, groundwater seepage, etc., vary over time. Some rivers respond quickly to rainfall runoff or snowmelt, while others respond more slowly depending on the size of the watershed, ...

How is the amount of water moving down a river measured?

The amount of water moving down a river at a given time and place is referred to as its discharge, or flow , and is measured as a volume of water per unit time, typically cubic feet per second or cubic meters per second. The discharge at any given point in a river can be calculated as the product of the width (in ft or m) times the average depth (in ft or m) times average velocity (in ft/s or m/s).

How to measure river discharge?

Now the final measurement you want to take at your site, to work out the discharge of the river, is a flow reading. You want to work out how fast that water is rushing past your feet. Now for this, the flow meter is the best option. However, if you do not have a flow meter, you can use a float and a tape measure and work out how fast that float flows down 10 meters of your stream. You can then convert that into a speed. With the flow meter, the propeller on the end spins as the water rushes past it and you get a reading in meters per second. As we take three readings across our river, you want to do it a quarter of the way across, a half of the way across, and three-quarters of the way across channel, making sure that you or anyone else in the group are with you, are not stood directly in front or behind the flow. You want to place the flow meter into the river 1/3 of the way down and record the flow in meters per second from the electronic box, every 10 seconds for one minute you. So here our first reading is naught .94 meters per second. Now we leave it another 10 seconds. Our next is naught .78. And you would then repeat this every 10 seconds for one minute, giving you six readings for the left-hand bank, one-quarter of the way across the river. You then repeat this at the halfway mark. So you're halfway across your river again, you want to place that flow meter a third of the way down into the channel. And again, every ten seconds for one minute record how fast that water is flowing in meters per second. You then repeat that on the right hand back three-quarters of the way across the river.

What do you need to measure the discharge of a river?

Ben: Now today I'm going to be showing you how to measure the discharge of a river. Now for this what you're going to need is a tape measure , a meter stick, a flowmeter, a couple of stakes to help you out, and a recording sheet to record your data.

Why divide width by 11?

The reason we divide it by 11 is because we're going to take a measurement at each of the banks.

What size tape measure should I use for river bank?

Now as I said before, for this you're going to need a tape measure, preferably let's say a 30-meter tape measure. Now from the left-hand bank, you want to have your 0-end of your tape measure.

What is the flow regime of a river?

The temporal patterns of high and low flows are referred to collectively as a river’s flow regime. The flow regime plays a key role in regulating geomorphic processes that shape river channels and floodplains, ecological processes that govern the life history of aquatic organisms, and is a major determinant of the biodiversity found in river ecosystems. There are five components that characterize the flow regime:

What is the term for the regularity of occurrence of different flow events?

Predictability: regularity of occurrence of different flow events. Rate of change or flashiness: how quickly flow changes from one magnitude to another. River in regions with similar climate, geology, and topography tend to have similar flow regimes.

What are the components of a flow regime?

There are five components that characterize the flow regime: Rate of change or flashiness: how quickly flow changes from one magnitude to another. River in regions with similar climate, geology, and topography tend to have similar flow regimes. For example, rivers draining high mountains, such as the Logan River, tend to have relatively infrequent, ...

Can natural flow regimes be determined from watershed characteristics?

Also, although general patterns in flow regime can be determined from watershed characteristics, yearly variation in precipitation patterns means that many years of flow monitoring will be required to fully characterize the flow regime of individual rivers.

How to measure river volume?

River volume is also sometimes measured in gauge feet. To get a handle on this concept, imagine a big ruler attached to a rock wall or stuck in the river; the gauge-feet flow is represented by where the waterline hits that ruler, (e.g. the 4' hash mark). Sometimes gauge feet can be equated with cfs; at other times, though, gauge feet is the only available indicator of water volume, and local historical knowledge (or your neighborhood paddle shop) will be needed to determine when that river or creek is best run. Other good sources for information are government websites, guidebooks, local boat shops, friends, or paddle clubs. It's a good idea to learn all you can beforehand about specific characteristics of the rivers you want to run this coming season.

Is it better to run the Salmon River or the Middle Fork?

For boaters, too much or too little flow can affect the runnability as well as the difficulty posed by a river. The Middle Fork of the Salmon, for example, is best run at 1,500-5,000 cfs, while the Lower Salmon River is best run around 15,000-20,000 cfs.

Streamflow and the Water Cycle

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Importance of rivers

Rivers are invaluable to not only people, but to life everywhere. Not only are rivers a great place for people (and their dogs) to play, but people use river water for drinking-water supplies and irrigation water, to produce electricity, to flush away wastes (hopefully, but not always, treated wastes), to transport merchandise, and to obtain food.

Streamflow is always changing

Streamflow is always changing, from day to day and even minute to minute. Of course, the main influence on streamflow is precipitation runoff in the watershed.

Hydrologists study streamflows with hydrographs

USGS uses a hydrograph to study streamflow in rivers. A hydrograph 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 water-quality parameters can also be plotted.

Precipitation influences streamflow

On Dec. 24, 2002, about two inches of rainfall fell in the Peachtree Creek watershed. This provides a good example to describe streamflow characteristics during a storm since the rain fell for only a few hours on that day and Peachtree Creek was at base-flow conditions before the rain started.

Mechanisms that cause changes in streamflow

Rivers are always moving, which is good for everything, as stagnant water doesn't stay fresh and inviting very long. There are many factors, both natural and human-induced, that cause rivers to continuously change:

Streamflow and global water distribution

Even though the water flowing in rivers is tremendously valuable to not only people but also to much of life on Earth, it makes up just a miniscule amount of Earth's water.

Why is it important to predict river flows?

Predicting and managing river flows is a necessity for flood control, water supply, agriculture and energy production. However, knowing how to measure these flows is a prerequisite. This constitutes hydrometry, a science distinct and complementary to hydrology (science of water in its natural environment) and hydraulics (physics of flows).

How much water flows through rivers each year?

On a global scale, nearly 36,000 km3 of water flows through rivers each year.

What is hydrometry process?

Finally, hydrometry is a process in the making: the availability of new imaging (LSPIV) and communication technologies (telephony, internet) will increase the flow of collected data. Questions will quickly arise about the processing of this information, its criticism and homogenization, its conservation, and the skills that accompany this massification of information. All this is in response to a real social demand for a better knowledge of the environment, a reduction in vulnerability to hazards, in the current context of climate change and the preservation of biodiversity.

How does hydrometry affect the environment?

Hydrometry is also a complex process, as it affects the natural environment, with all its associated hazards, and where the maturation times of the data can potentially be long. Thus, between information given on the spot (or even used to make a decision) and consolidated data after criticism or discovery of new elements, significant differences may appear (twice as much for an extreme regime value, in flood or drought) several years after their occurrence.

How many gauges per year for hydrometry?

It is considered that on the best stations (i.e. those where the calibration curve can be followed at a rate of less than 4 or 5 gauges per year), the current flows – encountered 80% of the time – are consolidated to within 5%.

What is the last part of hydrometry?

The conversion of heights into flow, the critique of the results, the archiving in the database are the last part of the hydrometry business.

What is direct flow measurement?

Direct flow measurement is a complex operation that can only be performed occasionally. Except in very specific cases, direct and continuous monitoring of the flow cannot be carried out. It is the water level that is measured continuously, after having previously connected it to the flow rate by a calibration curve.

Introduction to USGS Streamgaging

The U.S. Geological Survey (USGS) started its first streamgage in 1889 on the Rio Grande River in New Mexico to help determine if there was adequate water for irrigation purposes to encourage new development and western expansion.

How Streamflow is Measured

As you're enjoying yourself sitting on the peaceful bank of a local river, one question you may ask yourself is "How much water is flowing in this river?" You've come to the right place for an answer.

Measuring stream stage

Most U.S. Geological Survey (USGS) streamgages measure stage and consist of a structure in which instruments used to measure, store, and transmit the stream-stage information are housed. Stage, sometimes called gage height, can be measured using a variety of methods.

The discharge measurement

Discharge is the volume of water moving down a stream or river per unit of time, commonly expressed in cubic feet per second or gallons per day. In general, river discharge is computed by multiplying the area of water in a channel cross section by the average velocity of the water in that cross section:

The stage-discharge relation

Streamgages continuously measure stage, as stated in the "Measuring Stage"" section. This continuous record of stage is translated to river discharge by applying the stage-discharge relation (also called rating).

Streamflow summary

Streamgaging involves obtaining a continuous record of stage, making periodic discharge measurements, establishing and maintaining a relation between the stage and discharge, and applying the stage-discharge relation to the stage record to obtain a continuous record of discharge.

How does the size of a river change as it moves from the source to the mouth?

As the river moves from the source to the mouth – both the depth of the river and the width of the river will both increase. The load of a river will also change as it is transported and eroded along the river's profile. As a result, the size and shape of stones will change as they journey through the river profile.

What will happen to the discharge as the river approaches the sea?

The discharge will increase as the river approaches the sea.

What is the area of land that it drained by a river and its tributaries?

The drainage basin. A drainage basin is the area of land that it drained by a river and its tributaries. When a droplet of water falls onto the land (as precipitation), gravity will make sure that the water is ‘pulled’ downhill to return to the sea. Part of.

Where is the source of a river?

The source of a river is often, but not always, in an upland area. Near the source, a river flows over steep slopes with uneven surfaces.

What makes a river wider?

Lateral erosion makes a river wider. This occurs mostly in the middle and lower stages of a river.

What is the term for large materials rolled and pushed along the river bed by the force of the river?

Traction is when large materials such as boulders are rolled and pushed along the river bed by the force of the river.

How to tell the difference between competence and capacity?

The competence is the maximum size of load a river is able to carry whereas capacity is the total volume of material a river can transport . The competence of a river is the maximum particle size that a river can transport at a particular point. The Hjulström curve shows the relationship between river velocity and competence. It shows the velocities at which sediment will normally be eroded, transported or deposited. The critical erosion velocity curve shows the minimum velocity needed to for the river to erode (pick up) and transport material of different sizes (e.g. as bedload or in suspension). A greater velocity is required to erode material compared to just transporting it. The mean settling velocity curve shows the velocities at which different sized particles are deposited.

Why do rivers get muddy?

Suspension is when material made up of very fine particles such as clay and silt is lifted as the result of turbulence and transported by the river. Faster-flowing, turbulent rivers carry more suspended material. This is why river appear muddy as they are approaching bankfull discharge and towards the mouth of the river (where velocity is greater as is the occurrence of finer sediment).

What happens when a river scours the bed?

Where depressions exist in the channel floor the river can cause pebbles to spin around and turn hollows into potholes.

What are the processes of erosion?

There are four main processes of erosion that occur in rivers. These are: 1 hydraulic action; 2 abrasion / corrasion; 3 attrition; and 4 corrosion.

What is vertical erosion?

Vertical erosion makes a river channel deeper. This happens more in the upper stages of a river (the V of vertical erosion should help you remember the V-shaped valleys that are created in the upper stages).

How does the cross profile of a river change?

The cross profile of a river changes as it moves from the upper to lower course as a result of changes in the river’s energy and the processes that the river carries out.

How does load particle size affect river?

Load particle size decreases along the long profile of a river. Bedload becomes less angular along the course of a river.

Why does river discharge increase as you move downstream?

This is because tributaries will feed the river leading to an increase in discharge.

What is a hypothesis question?

A hypothesis is a statement, usually an educated guess, that you will either prove or disprove through the data you collect as part of your investigation.

What is the perimeter of a wetted river?

The wetted perimeter or occupied channel width is the entire length of the bed and river bank (sides) in contact with water.

How to measure dry bank?

Extend a tape measure from the point where the dry bank meets the water on one side of the river to the same point on the other side (hold it taut about 20cm above water level). Record the length, viewing the reading from directly above the tape measure.

What is the velocity of a river?

The velocity of a river is the speed the water flows. The velocity will change along the course of a river.