Open Channel 4. It should be noted that depth of flow varies in a section of a stream across the main flow direction.

See our Privacy Policy and User Agreement for details. 0000006304 00000 n If the side and bottom of the stream are far enough from the perimeter of the weir notch, the water particles approach the notch in converging paths in all directions, and continue to travel in curvilinear paths for some distance after leaving the notch, and cause the nappe to contract. For obtaining the average velocity in a strip, one can, alternatively, measure velocity only at 0.6 h depth below the free surface and take it equal to the average velocity in the strip. 0000015242 00000 n Only sharp crested weirs are commonly used. INTRODUCTION • As we know that the Precipitation, Evaporation and Evapotranspiration are all difficult to measure exactly but the Stream flow is the only part of the hydrologic cycle that can be measured accurately. Once the flow velocity is known, discharge can be calculated using Eq. 0000003181 00000 n At times, flood level marks on the banks can also be used for this purpose. The wetted perimeter (Wp) is the surface which is in con­tact with water. This would give surface velocity of the stream. Privacy Policy3. Discharge up to 75 sec-ft. or more can be measured with this weir. Flow in the river is measured as volume per unit of time. ... Hydrology, Irrigation, Methods for Steam Gauging, Stream Gauging. Discharge Measuring Structures. Unlike cup meters, propeller meters are sensitive to oblique flow, and the horizontal axis should be kept parallel to the direc­tion of the current. STREAM FLOW MEASUREMENT We will also measure the flow at a location on M ānoa stream itself, downstream from the lo‘i. The total discharge of the stream is the sum of such computations for the entire cross-section. I also ordered from, There is a useful site for you that will help you to write a perfect and valuable essay and so on. For the same area of cross-section, A, of the stream, the larger the wetted perimeter, the less is the velocity, v, of the stream and vice-versa, due to more frictional resistance.

The total discharge in the stream can be obtained by obtaining the sum of products of the average velocity and area of the strip for all the individual strips, i.e.. in which Bi, hi, vi and Qi, are width, average depth, average velocity and discharge of ith strip and the flow cross-section has been divided into N strips. The cable or rod is usually marked in feet. Check out, please ⇒ ⇐, No public clipboards found for this slide. for measuring flows ranging from 0.01 to 0.60 sec-ft. (ii) Intermediate-size flumes with throat widths of 6 in. HYDROLOGY - STREAMFLOW MEASUREMENT (SUPPLEMENTAL READIG) We will be making some stream flow measurements in an ‘auwai (irrigation ditch) that takes water from M ānoa Stream and diverts it to the Hawaiian Studies Dept.’s kalo lo‘i. 0000001424 00000 n in which Cd is the Coefficient of discharge, B the length of weir and g is the acceleration due to gravity. The velocity of flow in the channel is directly proportional to √R. For rating, the meter mounted on a trolley as moved with a definite velocity in still water cistern and the revolutions minute are recorded for each velocity and plotted on a graph. 688 0 obj << /Linearized 1 /O 691 /H [ 1640 3053 ] /L 917343 /E 118064 /N 84 /T 903464 >> endobj xref 688 52 0000000016 00000 n 0000001409 00000 n 0000001498 00000 n 0000004693 00000 n 0000004990 00000 n 0000005061 00000 n 0000005082 00000 n 0000005247 00000 n 0000005268 00000 n 0000005432 00000 n 0000005453 00000 n 0000005764 00000 n 0000007003 00000 n 0000007165 00000 n 0000007187 00000 n 0000007497 00000 n 0000008735 00000 n 0000009151 00000 n 0000009172 00000 n 0000009302 00000 n 0000009324 00000 n 0000010562 00000 n 0000010871 00000 n 0000011185 00000 n 0000013392 00000 n 0000013415 00000 n 0000014657 00000 n 0000016252 00000 n 0000016275 00000 n 0000016298 00000 n 0000016320 00000 n 0000017378 00000 n 0000017402 00000 n 0000032195 00000 n 0000032217 00000 n 0000033275 00000 n 0000033299 00000 n 0000099660 00000 n 0000099682 00000 n 0000100740 00000 n 0000100764 00000 n 0000114009 00000 n 0000114031 00000 n 0000115089 00000 n 0000115111 00000 n 0000115610 00000 n 0000115632 00000 n 0000116690 00000 n 0000116712 00000 n 0000117862 00000 n 0000001640 00000 n 0000004670 00000 n trailer << /Size 740 /Info 686 0 R /Encrypt 690 0 R /Root 689 0 R /Prev 903453 /ID[] >> startxref 0 %%EOF 689 0 obj << /Type /Catalog /Pages 667 0 R /JT 685 0 R /Outlines 665 0 R >> endobj 690 0 obj << /Filter /Standard /R 2 /O (m[@��@��\r'\r��c�?x=���z�o�+�$�) /U (���gU3O��@'> endobj 738 0 obj << /S 4407 /O 4909 /Filter /FlateDecode /Length 739 0 R >> stream The most commonly used structure for the purpose of discharge measure­ment in a river is a weir which is, generally, either triangular (for relatively small discharges) or rectangular (for relatively large discharges) in shape. A more workable and satisfactory formula carefully examined experimentally is the Manning’s formula given below (metric unit), n = roughness coefficient of the channel (Table 3.14).

Standard sharp-crested weirs are of the following types depending upon the shape of the weir notch: Following points must be considered in selecting the type of weir. (With Methods)| Industrial Microbiology, How is Cheese Made Step by Step: Principles, Production and Process, Enzyme Production and Purification: Extraction & Separation Methods | Industrial Microbiology, Fermentation of Olives: Process, Control, Problems, Abnormalities and Developments, The best answers are voted up and rise to the top. Rod suspension is more useful for gaging small streams or ditches. 0000000016 00000 n • A stream is defined as a flow channel into which the surface runoff from specified basin drains. What are the general characters of bryophytes? Area-Velocity Method 2. H and the weir characteristics. Both rotate around a horizontal axis by direct action of the current. The Parshall flume can be constructed in a wide range of sizes to measure discharge from a very small fraction of a second-foot to more than 3,000 sec-ft. Scribd will begin operating the SlideShare business on December 1, 2020 The floor of the throat inclines downward, and the floor of the diverging section slopes upward. Determination of C in Chezy’s formula is comparatively difficult. Hydrology, Irrigation, Methods for Steam Gauging, Stream Gauging. As of this date, Scribd will manage your SlideShare account and any content you may have on SlideShare, and Scribd's General Terms of Use and Privacy Policy will apply.

Name the types of nitrogenous bases present in the RNA. A weir consists of a bulkhead of timber, metal or concrete with an opening of fixed dimensions cut in its top edge. If you continue browsing the site, you agree to the use of cookies on this website. The USGS has been doing this since 1889, when it established its first stream gage on the Rio Grande River in New Mexico to determine how much water was availa… The cup meter has six conical cups mounted on a vertical axis pivoted at the ends and free to rotate between the rigid arms of a U-shaped clevis to which a vaned tailpiece is attached (Fig. This is a question and answer forum for students, teachers and general visitors for exchanging articles, answers and notes. Basically, the current meter is a wheel having several cups or vanes which turn round due to the force of water current.

3.16. Weirs are generally not well suited for water carrying silt which deposits in the channel of approach and destroys the proper conditions for accurate meas­urement. The cup meter and the propeller meter. Water surface slope S can also be computed using the gauge level readings and the distance between the two gauge stations. In the former a vaned tailpiece is used to keep the meter facing into the current. What are the modifications that are observed in birds that help them fly? COOPERATIVE RESEARCH CENTRE FOR CATCHMENT HYDROLOGY iii Summary The usual measurement of the state of a river at a gauging station is that of the stage, the surface elevation. In this method, a float rests on the water in a float well which is connected to the main channel by a pipe or trench. 0000008023 00000 n 3.13). Mean velocity of the stream is often taken as 0.8 to 0.9 of the average surface velocity. This weir gives most accurate results when measuring small discharge of less than 1 sec-ft. to a maximum of 10 sec-ft. The larger-size flumes have an approach floor and wing walls at the upstream end. The traditional unit of measure in the United States is cubic feet per second (cfs), although measurements today are often in cubic meters per second. A number of such observations give a fairly correct surface velocity.

You'll be glad you did. Its value depends upon the nature of soil material, its wetness and density (Table 3.13). With the current meter make the measurements necessary to determine the mean velocity v2 at vertical line 2. 0000005533 00000 n Explain the factors which cause dormancy.

Rotation is made by greater pressure from the current being exerted on the inner side of the cup than its outer side. Weirs and flumes may be constructed across small streams or channels for cal­culating the discharge from the knowledge of depth of overflow, using hydraulic equations. ��D&���8���.���¥}�`}�4�;�o�J~�!�}������

If you wish to opt out, please close your SlideShare account. The screw meter and the spooked meter with vanes. Measuring Streamflow. v1 and v2 = mean velocities in the two verticals d1 and d2. 3.14). The discharge of each segment of the cross-section (area between adjacent verticals) is the product of the area of the segment and the mean velocity in the segment, that is: where, d1 and d2 = depths of flow at two adjacent verticals.

(a) The head should range between 0.2-2 ft. (b) For rectangular and trapezoidal weirs, the head should not exceed 1/3 of the weir length. xref The best method for stream flow measurement would, therefore, be to determine the velocity variation at a channel section and then integrate (i.e., sum) the products of velocity in a small individual elemental area with that area for the whole flow cross-sec­tion. Rating Marts are generally provided by manufacturers along with the instrument, however, the current meter should be rated at-least once a year. 0000007828 00000 n 0000007899 00000 n 0000007763 00000 n The selected length of notch should be more than 3 H to 4 H. The discharge up to 75 sec-ft or more can be measured with the help of trapezoidal weir. Direct and Indirect method to measure streamflow. 0000007093 00000 n to 8 ft. for measuring flows ranging from 0.50 to 130 sec-ft. (iii) Larger-size flumes with throat widths of 10 to 50 ft. adapted to the measurement of stream-flows of 10 to more than 3,000 sec-ft. 3.12, where: t = width of the water surface when the water is at depth d, D = depth of channel after free board is added, 0 = angle between the sloping side and the horizontal. Propeller meters are available in two forms. MOHIT MAYOOR What is seed dormancy? �ɭX�Q?K���ԝM��!�R��0�OW�0���Qx^e!�R�#D�`&ےx펕���?��Ŷ��2�ۨ2�+�!�&��S`�oG=B�ٴx;%�I�;��8��fH��N N����L@�����C�>�7O��!�N2Z�$g ճ҉w��ôFVӇ�Fs>��ٚc��� I:�©,� )�&�Naukc�� 9QZ�ܡ4߂:|��� �������=��uO�ԝ��P).b�U}���U� 1�>Нa#��c�P���Ez����/eQ���9;�Sb膧҅����p[��~�8 0000001037 00000 n Current Meter 2. 28 0 obj <> endobj


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