BS ISO 26906:2015 pdf download

BS ISO 26906:2015 pdf download.Hydrometry — Fishpasses at flow measurement structures
1 Scope
This International Standard specifies requirements for the integration of fishpasses with flow measurement structures. It identifies those fishpasses which have satisfactory hydrometric calibration data and gives methods for computing combined flows and uncertainties. NOTE Flow measurement structures and fishpasses have inherently different hydraulic performance criteria. Flow measurement structures perform better with uniform flow patterns; conversely, fish passage performance is improved by the variability of the flow conditions that allow fish and other aquatic inhabitants to select the passage conditions that best meet their mode of movement. This International Standard does not suggest that the fishpasses discussed are the preferred methods of fish passage or that they are good enough that passage performance can be sacrificed to obtain a single structure that meets both the fish passage and flow measurement requirements.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 772, Hydrometry — Vocabulary and symbols
ISO 14139, Hydrometric determinations — Flow measurements in open channels using structures —Compound gauging structures
3 Terms and definitions
For the purpose of this document, the terms and definitions given in ISO 772 and the following apply.
3.1 fish pass design range
range of flows within which fish require passage
Note 1 to entry: This may be defined on an annual or a seasonal basis, e.g. for spawning.
Note 2 to entry: In some countries the design range is determined in terms of flow statistics. For example, the design range for coarse fish in the UK is usually between the estimated mean daily flow that is exceeded 95 % of the time and the mean daily flow that is exceeded 20 % of the time. While for migratory salmonids including sea trout and salmon, it is 95 % and 90 % to 10 % respectively.
5 Principle
The discharge over a flow measurement structure is a function of the upstream head (plus a measure of the downstream head in the case of those structures designed to operate in the non-modular flow range). When a fishpass is placed alongside a flow gauging structure, an additional flow path is created. In certain circumstances, where the fishpass has a well-defined hydrometric calibration, total flows and uncertainties may be calculated. Thus the fishpass becomes an integral part of the flow measurement system. This International Standard provides the necessary design and performance information for this type of arrangement.