1、INTERNATIONAL STANDARD ISO 11329 Second edition 2001-05-01 Reference number ISO 11329:2001(E) ISO 2001 Hydrometric determinations Measurement of suspended sediment transport in tidal channels Dterminations hydromtriques Mesurage du transport solide dans les canaux mareISO 11329:2001(E) ii ISO 2001 A
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5、given below. ISO 2001 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs mem
6、ber body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch Printed in SwitzerlandISO 11329:2001(E) ISO 2001 All rights reserved iii Contents Page 1 Scope . 1 2 Normative reference
7、s . 1 3 Terms and definitions 1 4 Salient features of sediment transport in tidal channels . 2 5 Guidelines for measurement and estimation of suspended sediment transport . 2 6 Selection of sampling site in the tidal channel 3 7 Principles of measurement . 4 8 Estimation of suspended sediment transp
8、ort . 5 Bibliography. 6ISO 11329:2001(E) iv ISO 2001 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO tec
9、hnical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closel
10、y with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to
11、 the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. ISO shall not be held re
12、sponsible for identifying any or all such patent rights. International Standard ISO 11329 was prepared by Technical Committee ISO/TC 113, Hydrometric determinations, Subcommittee SC 6, Sediment transport. This second edition cancels and replaces the first edition (ISO 11329:1998), which has been tec
13、hnically revised.ISO 11329:2001(E) ISO 2001 All rights reserved v Introduction Estuaries and creeks have become regions of major developments pertaining to port and harbour facilities, navigation, reclamation and effluent disposal. Human interference with water bodies, for example, providing navigat
14、ional channels, installing major or minor structures and reclaiming land, need thorough examination of their impact on morphological changes, stability of banks and channels, the consequences of capital and maintenance dredging, and the selection of disposal grounds. For these purposes, it is necess
15、ary to estimate the suspended sediment transport rates in tidal channels, which can be based on data on morphological characteristics of the channel, flowrates and the corresponding suspended sediment concentration. In comparison to the situation in unidirectional flow, the flow as well as sediment
16、concentration at different locations along tidal channels are much more complex. The salt water flow from the sea at one end and the fresh water flow from the river at the other end are responsible for spatial and temporal variations in water and sediment movement in tidal channels. When measuring t
17、he flowrate and suspended sediment concentrations for estimating sediment transport rates, these factors need to be considered.INTERNATIONAL STANDARD ISO 11329:2001(E) ISO 2001 All rights reserved 1 Hydrometric determinations Measurement of suspended sediment transport in tidal channels 1 Scope This
18、 International Standard deals with the method and techniques for the sampling of suspended sediment and esti- mation of sediment transport rates in natural and man-made channels influenced by tidal action. 2 Normative references The following normative documents contain provisions which, through ref
19、erence in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publica- tions do not apply. However, parties to agreements based on this International Standard are encouraged to investi- gate the possibility of
20、 applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain reg- isters of currently valid International Standards. ISO 772, Hydrometric determinations Vocabul
21、ary and symbols. ISO 2425, Measurement of liquid flow in open channels under tidal conditions. 3 Terms and definitions For the purposes of this International Standard, the terms and definitions given in ISO 772 and the following apply. 3.1 mixed tides tides which have two markedly unequal successive
22、 high waters, or two markedly unequal successive low waters, or both, during most of each month 3.2 divergence deviation of the angle between the flood and ebb axes from NOTE In a straight reach, the flood and ebb flow directions are ideally expected to lie on the same axis but in the opposite direc
23、tion, i.e. the change in flow direction is . However, in most situations the directions of flood and ebb flows are not along the same axis, due to prevailing approach conditions from either side. 3.3 flood ebb predominance net flow, in the flood ebb direction, resulting when the flood ebb velocity-t
24、ime curve is such that the net flow integrated over a tidal period, either at a point or over a vertical, is not zero NOTE In a typical situation, one part of a tidal channel may have flood predominance whereas the other may have ebb predominance. 3.4 creek inlet or arm of a river or a small stream
25、joining the coast 180 180 ISO 11329:2001(E) 2 ISO 2001 All rights reserved 4 Salient features of sediment transport in tidal channels Measurement of discharge and estimation of corresponding suspended sediment concentration by analysis of water samples are essential to estimating the rate of sedimen
26、t transport through a channel section. The following aspects shall be taken into account when planning the collection of data and estimation of sediment transport. a) Flow is two-way in tidal channels as a result of tidal fluctuation in the sea. During the flood phase, the water level rises and wate
27、r flows from the sea upstream, whereas during the ebb phase, the water level falls and water flows toward the sea. b) The extent of tidal excursion, magnitude and direction of tidal current, and flood and ebb periods (at any cross- section) differ from tide to tide depending on the tidal range and f
28、reshwater discharge. c) The variation in water level from section to section in a tidal channel depends on the freshwater discharge, tidal range in the sea, the channel bed slope and frictional resistance at the bed and banks of the channel. d) All the above aspects result in temporal and spatial va
29、riation in the sediment transport at all points in a tidal channel. e) The quantity and type of sediment which enters a tidal channel depends on the freshwater discharge, the wave climate and tides in the sea. As a result, there can be a large variation in the amount of suspended load in tidal chann
30、els. f) The variation in the strength of the current from spring to neap or from neap to spring results in significant changes in the bed configuration along the channel. Variation in the freshwater discharge also causes such changes. g) The directions of flood and ebb currents in a cross-section of
31、 the tidal channel do not necessarily differ by (i.e. complete reversal) as the flow is governed by the bed and bank configurations upstream of flow. Furthermore, the flood flow may dominate one part of the cross-section whereas the ebb flow dominates the other part. h) The time of reversal and the
32、direction of transport are commonly different across the cross-section of the tidal channel and at different depths on a vertical. i) In a wide channel near the mouth, the time of reversal from flood to ebb or from ebb to flood differs appreciably from one part to another in the section, resulting i
33、n a large circulation. j) The difference in densities of sea water and river water affects the mixing characteristics of tidal and freshwater flows, depending on their relative magnitudes. The flow in the channel can be well-mixed, partially mixed or stratified. k) Water level is affected by atmosph
34、eric pressure fluctuations and wind drag. l) Biological effects can determine the erosivity within an estuary, which can affect the suspended sediment concentrations in time and space. m) Variations in temperature change water viscosity and also affect the settling velocity of different sediments, t
35、hus affecting the suspended sediment load throughout the year. n) Human activities, such as dredging, disposal and trawling, will also influence the amount of suspended sediment within the water column. 5 Guidelines for measurement and estimation of suspended sediment transport Consideration should
36、be given to the following points for the measurement and estimation of suspended sediment transport in a tidal channel. a) Long-term measurements of flow and simultaneous water sampling are required for estimating sediment transport in tidal channels. For regular semidiurnal tides, data should be co
37、llected for a minimum of . However, in the case of diurnal tides or where there is a strong diurnal component (mixed tides), an observation period of is recommended. The time interval between the observations shall also be kept as small as possible (no more than ) due to the unsteady nature of tidal
38、 flow. b) The period of data collection may need to cover various ranges of tide, from neap to spring, to account for the variation in velocity and suspended sediment concentration if morphological changes are to be estimated. 180 13 h 25 h 0,5 hISO 11329:2001(E) ISO 2001 All rights reserved 3 c) Du
39、ring the preliminary survey, the mixing characteristics of the tidal channel shall be identified by taking simultaneous observations at the surface and at the bed. If the flow is stratified, it may be necessary to extend the observation period to cover a period from neap to spring tides. d) As the p
40、resence of freshwater discharge affects the flow field and sediment transport, collection of data is necessary to cover both dry and freshet seasons. e) Items a) through d) emphasize the need for long-term observations. Depending on the hydraulic conditions, a decision should be taken on the require
41、d period and time of observations necessary to serve the purpose for which the investigation is undertaken. It may also be possible to limit the field observations if suitable numerical models are available to simulate the range of prevailing hydraulic conditions. f) The scatter in data for suspende
42、d sediment concentration is more than for unidirectional flow in tidal channels, due to the variable nature of the flow. Repeated observations for the same tidal conditions are therefore necessary to arrive at a reliable estimation of sediment transport. g) The sampling points on a vertical need to
43、be changed with variation in flow depth in a tidal cycle. The sampling points should be selected on the basis of depth of stratification for stratified flow. h) The level of the sampling point with respect to the water surface is easily measured. However, the elevation of water surface itself change
44、s with time. This change shall be taken into account while analysing and interpreting the data in absolute terms. The simultaneous measurement of water level with respect to a known datum is necessary. i) Simultaneous observations are desirable at several verticals in a section of the tidal channel,
45、 as well as at a number of sections, depending on the reach to be covered. This requires more resources with respect to boats, equipment and personnel so as to determine the effects of variations on flows. j) Point sampling is better than depth-integrated sediment sampling in tidal channels. k) Duri
46、ng the collection of data over long observation periods (even covering one tidal cycle), problems may arise due to ships in the navigation channel and dredging activity. Considering these problems, as well as the limitation of resources in carrying out simultaneous observations at a number of locati
47、ons, it may be necessary to utilize data collected from different tides of the same range to cover the different locations, keeping at least one common observation station for reference. l) Though the values of suspended sediment flux during the flood and ebb phases can be very large, the value of t
48、he net flux (algebraic sum of flood and ebb fluxes) can be very small. Errors in the estimation of flood and ebb sediment fluxes may therefore result in a significant error in the magnitude and perhaps even in the direction of the net flux. Therefore great care shall be taken to minimize errors in t
49、he basic measurements. 6 Selection of sampling site in the tidal channel 6.1 Choice of cross-section It is desirable to carry out a preliminary survey to choose a suitable site preferably satisfying the conditions given be- low, in addition to those conforming to ISO 2425. a) The banks of the cross-section of the tidal channel should not be too flat, in order to avoid large intertidal variation in water-surface width. b) There should not be appreciable divergence between predominant flood and
