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Methods for Determining Stream Discharge: 1) Select a site to measure the stream's wetted width, record it, and divide it into at least 10 equidistant intervals (no interval should exceed 3 meters in width). 2) At each interval measure and record the depth. With a current meter (adapted from F.R. Hauer and G.A. Lamberti. 1996. Methods in Stream Ecology. Academic Press.): 3) At each interval, place the current meter into the stream, with the meter facing into the current and the operator standing downstream of the current meter. Make sure that eddies around the operator's legs do not disturb the activity of the current meter. 4) If the depth is less than 60 cm, read the velocity at 0.4 x D, measured upward from the streambed. If depth is greater than 60 cm., read and record velocities for 0.2 x D and 0.8 x D. The mean velocity is the average of the two velocities. 5) It the water column for the cell being measured contains large submerged objects (logs, boulders, etc...) or is disturbed by overhanging vegetation, read and record the velocities at 0.2D 0.4D, and 0.8D. Calculate the mean velocity as V = 0.25(V0.2 + V0.4 + V0.8) 6) If the velocities are extremely high or flood flows exist, measure and record the velocity at the surface. Calculate the mean velocity using the equation V = kVs, where k = 0.85. With a float (adapted from C.C. Harrelson, C.L. Rawlins, and J.P. Potyondy. 1994. Stream Channel Reference Sites: An Illustrated Guide to Field Technique. USDA Forest Service General Technical Report RM-245): 3) Measure a length of stream that approximates two to three channel widths. This is the designated reach length, L. This section should overlap one of the sections being measured for cross-sectional area if possible. Mark the upper and lower ends of this interval with a stake or a string across the stream. 4) Choose a float that is only slightly buoyant (Oranges are commonly used), this will minimize the influence of air currents and provide a more accurate representation of stream velocity. 5) Introduce the float a slight distance upstream of the upstream marker so that the float can reach the speed of the water prior to passing the upstream marker. In large rivers (> 10 m in width), divide the stream into thirds and make several passes with the float in each third to obtain an average velocity. 6) Use a stopwatch or wristwatch to measure the time (t) of travel of the float between the upstream and downstream marks. Record several measurements through each section to obtain an average. Surface velocity is calculated as Vs = L/t. A correction factor, k, for the roughness of the bed must be applied to estimate the mean velocity, V: V = kVs. The correction factor varies between 0.8 for rough beds and 0.9 for smooth beds, but 0.85 is most commonly used. Steps 7 and 8 will require the use of a calculator or a computer and may be completed after leaving the field. 7) Calculate and record the discharge for each cell (n) as Qn = wnDnVn, where wn is the width of the cell (m); Dn, the depth of the cell at the midpoint (m); and Vn, mean velocity of the cell at the midpoint (m/s). 8) Discharge (Q) for the transect is calculated as: Q = sum of Qn = w1D1V1 + w2D2V +.....+ wnDnVn Source: http://waterontheweb.org/curricula/ws/unit_01/Mod_4_5/Measuring%20Discharge.doc
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What does the rate of stream discharge has to do with erosion and deposition?
rate of stream discharge is directly proportional to the erosion i.e the higher the velocity of the stream then it will erode the rock rapidly while the deposition process will be slow when the velocity will be high.
Increasing the steepness of a river's bed is LEAST likely to change the size of the discharge of a stream and the?
volume of water flowing in the stream
How does an increase in a streams velocity affect its discharge and carrying capacity?
When the discharge of a stream increases, so does it's velocity. When it decreases, so does the velocity.
In a typical stream where the gradient is steep the discharge is what?
A steep gradient will force the water to flow downhill faster.
Why is the coefficient of discharge of a venturimeter calculated?
A discharge coefficient is used to account for inaccuracies resulting from assuming plug flow and neglecting friction in the Bernoulli equation.
What happens to stream speed if the discharge in a stream doubles?
If in a given stream the velocity doubles, the discharge: Choose one answer
What happens after stream discharge increases?
After a stream's discharge increases, it overflows its banks and a flood occurs.
In a typical stream where the gradient in steep the discharge is?
In a typical stream where the gradient is steep the discharge is small.
In a typical stream where the gradient is steep the discharge .?
In a typical stream where the gradient is steep the discharge is small.
If a stream's discharge decreases how does it affect the stream's capacity?
The capacity of a stream is the maximum load it can carry. Capacity is directly related to a stream's discharge. The greater the volume of water in a stream is, the greater its capacity is for carrying sediment. So if a stream's discharge decreases, the stream's capacity also decreases.
What happens after a stream discharge increases?
After a stream's discharge increases, it overflows its banks and a flood occurs.
What does A stream discharge .?
Water.
What is a discharge of a stream?
a discharge of a stream is the amount of water flowing past a certain point in a given unit of time.
In a typical stream where the gradient is steep the discharge is?
In a typical stream where the gradient is steep the discharge is small.
Why a stream discharge increase?
Stream discharge would increase if additional water enters it, such as from a rain storm or from melting snow.
What is the definition of stream discharge?
stream discharge is the amount of water flowing through a space OR increases between its source or mouth
When does a stream discharge decrease?
Yea
