GROUP 6. RIMBERIO CO. Bitco Jaranilla Yu. 

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STREAM FLOW. • A stream is defined as a flow channel into which the surface runoff from specified basin drains. • The discharge flowing in a stream is called stream flow. 

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• A stream is defined as a flow channel into which the surface runoff from specified basin drains.  •  The discharge flowing in a stream is called stream flow

STREAM DISCHARGE. Stream discharge is derived from four sources: channel precipitation, overland flow, interflow, and groundwater .. 

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Stream discharge is derived from four sources:  channel precipitation, overland flow, interflow, and groundwater .

where Q is discharge (volume/unit time-e.g. m 3 /second, also called cumecs),  A is the cross-sectional area of the stream (e.g. m 2), and  V is the average velocity (e.g. m/s).

2 STEPS EMPLOYED IN STREAM FLOW MEASUREMENTS. Step 1. 

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2 STEPS EMPLOYED IN STREAM FLOW MEASUREMENTS

Discharge of the stream is related to the stage using a series of measurements. a stage discharge relationship is developed, know as RATING CURVE.

Water level/stage is observed routinely Corresponding discharge is observed from the rating curve.

STAGE MEASUREMENT TECHNIQUES. Non recording/ Manual stream gauges. 

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Staff Gauge Wire Gauge Electric Tape Gauge

VERTICAL STAFF GAUGE. Staff/post with markings for measurement of water level.. 

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Staff/post with markings for measurement of water level.

Fixed either to the abutment, pier or wall.

It may not be possible to read the entire range of  water-surface elevations of a stream by a single gauge.

Such cases the gauge is built in sections at different locations.

WIRE GAUGE. Wire is lowered from the permanent strcutures (E.e. Bridge, Pier) such that the weight attached at the end of the wire touches the water surface.. 

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Wire is lowered from the permanent strcutures (E.e. Bridge, Pier) such that the weight attached at the end of the wire touches the water surface.

The length of the wire coming out of the drum of the gauge is read by a mechanical counter attached to a reel on which the wire or tape is wound.

That length is subtructed from the reference datum.

The weight is replaced by an electric device.

Recorder Approach bridge tage gauge Intake pipes Intake well Stilling well installation. 

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Recorder
Approach bridge
tage gauge
Intake pipes
Intake well
Stilling well installation

AUTOMATIC WATER LEVEL RECORDER OR FLOAT GAUGE RECORDER

Measures water level continuously. It works in the principle of a float. A surface float is connected to one end of the wire which passes through a recorder. Fluctuations in water surface level cause the float, rope and the wheel of the recorder to move. hence, the pully rotates and the stylus records the movement.

STREAM FLOW MEASUREMENT TECHNIQUES. can be broadly classified into two categories:. 

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can be broadly classified into two categories:

DIRECT DETERMINATION. Area Velocity Method. 01. Electro-magnetic Method. 

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the most common method of estimating river flow. As the term implies, the flow is the product of the average velocity in the cross-section and the cross-sectional area of flow.

involves injecting (inserting) a known amount of salt into a stream. This process is technically known as slug injection.

Vibration diagnostics is based on using an external magnetic field.

The velocity of flow is measured by transmitting an ultrasonic pulse diagonally across the channel in both directions simultaneously.

INDIRECT DETERMINATION. Hydraulic Structures. 01. 

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play an important role in drainage, irrigation, and hydraulic projects. If hydraulic structures fail, it may cause serious damages of wealth, properties, and environment as well as losses of life and injury to economy.

is the most commonly used technique of indirect discharge determination. In the slope-area method, discharge is computed on the basis of a uniform-flow equation involving channel characteristics, water-surface profiles, and a roughness or retardation coefficient.

1 . Discharge measurement Using Mid method s 9 10 4 2. 

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1 . Discharge measurement Using Mid method
s 9 10
4
2

2. Discharge measurement Using Mean method
o For first end cross sections
o For last end cross sections

Example: Determine the dischargdusing both mean section and mid section method? vert. 12 13 14 19 Dist. 10 13 14 24 0.00 0.31 040 oss 1.19 0.92 070 063 oss 048 0.00 0.6d 0.000 o. 193 079 0238 0143 0216 ouz 0150 ons 0.000 Veloci , m/s O.2d ous 028 oss 0.317 027 ous 027 028 ous oas 0.8d 026 ozs 028 0.252 0138 0138 027 0.193 0.138. 

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Example:
Determine the
dischargdusing both
mean section and
mid section method?
vert.
12
13
14
19
Dist.
10
13
14
24
0.00
0.31
040
oss
1.19
0.92
070
063
oss
048
0.00
0.6d
0.000
o. 193
079
0238
0143
0216
ouz
0150
ons
0.000
Veloci , m/s
O.2d
ous
028
oss
0.317
027
ous
027
028
ous
oas
0.8d
026
ozs
028
0.252
0138
0138
027
0.193
0.138

Example:. A Velocity of 2ft/s is measured with a current meter placed 0.4 ft above the bottom of a small stream. The estimated cross-sectional area of the stream is 2 sq ft, and the flow depth is 1 ft. What is the estimated flow rate?. 

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A Velocity of 2ft/s is measured with a current meter placed 0.4 ft above the bottom of a small stream. The estimated cross-sectional area of the stream is 2 sq ft, and the flow depth is 1 ft. What is the estimated flow rate?

Example:. Determine the discharge of a stream having a cross-section area of 50 sq ft and a wetted perimeter of 16 ft, using the slope-area method. The difference in elevation of the water surface 500 ft apart is 0.3 ft. The channel has straight banks with some weeds.. 

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Determine the discharge of a stream having a cross-section area of 50 sq ft and a wetted perimeter of 16 ft, using the slope-area method. The difference in elevation of the water surface 500 ft apart is 0.3 ft. The channel has straight banks with some weeds.

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