| PDF Pages<\/th>\n | PDF Title<\/th>\n<\/tr>\n | ||||||
|---|---|---|---|---|---|---|---|
| 3<\/td>\n | TitlePage – Hydrometric determinations\ufffd\u2014 Flow measurement in open channels using structures\ufffd\u2014 Fla… <\/td>\n<\/tr>\n | ||||||
| 5<\/td>\n | TableofContent – Contents Page <\/td>\n<\/tr>\n | ||||||
| 6<\/td>\n | Foreword – Foreword <\/td>\n<\/tr>\n | ||||||
| 7<\/td>\n | Scope – 1\ufffd\ufffd\ufffd Scope NormativeReference – 2\ufffd\ufffd\ufffd Normative references <\/td>\n<\/tr>\n | ||||||
| 9<\/td>\n | Clause1 – 4\ufffd\ufffd\ufffd Symbols <\/td>\n<\/tr>\n | ||||||
| 10<\/td>\n | Clause1 – 5\ufffd\ufffd\ufffd Characteristics of flat-V weirs Clause1 – 6\ufffd\ufffd\ufffd Installation Subclause2 – 6.1\ufffd\ufffd\ufffd Selection of site UntitledSubclause3 – 6.1.1\ufffd\ufffd\ufffd The weir shall be located in a straight section of the channel, avo… UntitledSubclause3 – 6.1.2\ufffd\ufffd\ufffd A preliminary study of the physical and hydraulic features of the p… <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | UntitledSubclause3 – 6.1.3\ufffd\ufffd\ufffd If the site does not possess the characteristics necessary for sati… <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | Subclause2 – 6.2\ufffd\ufffd\ufffd Installation conditions Subclause3 – 6.2.1\ufffd\ufffd\ufffd General requirements Subclause3 – 6.2.2\ufffd\ufffd\ufffd Approach channel UntitledSubclause4 – 6.2.2.1\ufffd\ufffd\ufffd If the flow in the approach channel is disturbed by irregularitie… UntitledSubclause4 – 6.2.2.2\ufffd\ufffd\ufffd A minimum required length of straight approach channel shall be f… UntitledSubclause4 – 6.2.2.3\ufffd\ufffd\ufffd In a natural channel where it is uneconomic to line the bed and b… UntitledSubclause4 – 6.2.2.4\ufffd\ufffd\ufffd Vertical side walls constructed to effect a narrowing of the natu… UntitledSubclause4 – 6.2.2.5\ufffd\ufffd\ufffd In a channel where the flow is free from floating and suspended d… UntitledSubclause4 – 6.2.2.6\ufffd\ufffd\ufffd Under certain conditions, a hydraulic jump may occur upstream of … UntitledSubclause4 – 6.2.2.7\ufffd\ufffd\ufffd Conditions in the approach channel can be verified by inspection … <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | Subclause2 – 6.3\ufffd\ufffd\ufffd Weir structure UntitledSubclause3 – 6.3.1\ufffd\ufffd\ufffd The structure shall be rigid and watertight and capable of withstan… UntitledSubclause3 – 6.3.2\ufffd\ufffd\ufffd The weir and the approach channel as far as the upstream tapping po… UntitledSubclause3 – 6.3.3\ufffd\ufffd\ufffd In order to minimize uncertainty in the discharge, the following to… UntitledSubclause3 – 6.3.4\ufffd\ufffd\ufffd The structure shall be measured upon completion and mean dimensiona… Subclause2 – 6.4\ufffd\ufffd\ufffd Downstream conditions Clause1 – 7\ufffd\ufffd\ufffd Maintenance <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | Clause1 – 8\ufffd\ufffd\ufffd Measurement of head(s) Subclause2 – 8.1\ufffd\ufffd\ufffd General Subclause2 – 8.2\ufffd\ufffd\ufffd Gauge wells UntitledSubclause3 – 8.2.1\ufffd\ufffd\ufffd It is common practice to measure the upstream head in a gauge well … UntitledSubclause3 – 8.2.2\ufffd\ufffd\ufffd Gauge wells shall be vertical and of sufficient height and depth to… UntitledSubclause3 – 8.2.3\ufffd\ufffd\ufffd Both the well and the connecting pipe shall be watertight. Where th… UntitledSubclause3 – 8.2.4\ufffd\ufffd\ufffd The invert of the pipe shall be positioned at a distance of no less… UntitledSubclause3 – 8.2.5\ufffd\ufffd\ufffd Pipe connections to the upstream and downstream head measurement po… UntitledSubclause3 – 8.2.6\ufffd\ufffd\ufffd The static head at the separation pocket behind the crest of the we… <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | UntitledSubclause3 – 8.2.7\ufffd\ufffd\ufffd Adequate additional depth shall be provided in wells to avoid the d… UntitledSubclause3 – 8.2.8\ufffd\ufffd\ufffd The diameter of the connecting pipe or width of slot to the upstrea… Subclause2 – 8.3\ufffd\ufffd\ufffd Zero setting UntitledSubclause3 – 8.3.1\ufffd\ufffd\ufffd Accurate initial setting of the zeros of the head measuring devices… UntitledSubclause3 – 8.3.2\ufffd\ufffd\ufffd An accurate means of checking the zero at frequent intervals shall … UntitledSubclause3 – 8.3.3\ufffd\ufffd\ufffd A zero check based on the water level (either when the flow ceases … <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | UntitledSubclause3 – 8.3.4\ufffd\ufffd\ufffd Values for the crest cross-slope, Subclause2 – 8.4\ufffd\ufffd\ufffd Location of head measurement sections UntitledSubclause3 – 8.4.1\ufffd\ufffd\ufffd The approach flow to a flat-V weir is three dimensional. Drawdown i… UntitledSubclause3 – 8.4.2\ufffd\ufffd\ufffd If other considerations necessitate siting the tapping closer to th… UntitledSubclause3 – 8.4.3\ufffd\ufffd\ufffd Flat-V weirs can be used for gauging purposes in the drowned flow r… <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | UntitledSubclause3 – 8.4.4\ufffd\ufffd\ufffd Alternatively flat-V weirs can be used for gauging purposes in the … Clause1 – 9\ufffd\ufffd\ufffd Discharge relationships Subclause2 – 9.1\ufffd\ufffd\ufffd Equations of discharge UntitledSubclause3 – 9.1.1\ufffd\ufffd\ufffd In terms of total head, the basic discharge equation for a flat-V w… <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | UntitledSubclause3 – 9.1.2\ufffd\ufffd\ufffd In terms of total head, the basic discharge equation for a flat-V w… <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | Subclause2 – 9.2\ufffd\ufffd\ufffd Effective heads Subclause2 – 9.3\ufffd\ufffd\ufffd Shape factors Subclause2 – 9.4\ufffd\ufffd\ufffd Coefficient of velocity UntitledSubclause3 – 9.4.1\ufffd\ufffd\ufffd The coefficient of velocity, UntitledSubclause3 – 9.4.2\ufffd\ufffd\ufffd The coefficient of velocity, <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | Subclause2 – 9.5\ufffd\ufffd\ufffd Conditions for modular\/drowned flow <\/td>\n<\/tr>\n | ||||||
| 24<\/td>\n | Subclause2 – 9.6\ufffd\ufffd\ufffd Drowned flow reduction factor UntitledSubclause3 – 9.6.1\ufffd\ufffd\ufffd The drowned flow reduction factor, UntitledSubclause3 – 9.6.2\ufffd\ufffd\ufffd In UntitledSubclause3 – 9.6.3\ufffd\ufffd\ufffd In the absence of crest tappings, downstream tappings may be used t… <\/td>\n<\/tr>\n | ||||||
| 31<\/td>\n | Subclause2 – 9.7\ufffd\ufffd\ufffd Limits of application UntitledSubclause3 – 9.7.1\ufffd\ufffd\ufffd The practical lower limit of upstream head is related to the magnit… UntitledSubclause3 – 9.7.2\ufffd\ufffd\ufffd There is also a limiting value for the ratio UntitledSubclause3 – 9.7.3\ufffd\ufffd\ufffd There is a limiting Froude number for the flow conditions in the ap… Clause1 – 10\ufffd\ufffd\ufffd Computation of discharge Subclause2 – 10.1\ufffd\ufffd\ufffd General Subclause2 – 10.2\ufffd\ufffd\ufffd Successive approximation method Subclause3 – 10.2.1\ufffd\ufffd\ufffd Computation using individual head measurements <\/td>\n<\/tr>\n | ||||||
| 32<\/td>\n | Subclause3 – 10.2.2\ufffd\ufffd\ufffd Computation of modular stage-discharge function <\/td>\n<\/tr>\n | ||||||
| 33<\/td>\n | Subclause2 – 10.3\ufffd\ufffd\ufffd Coefficient of velocity method Subclause3 – 10.3.1\ufffd\ufffd\ufffd Modular flow conditions Subclause3 – 10.3.2\ufffd\ufffd\ufffd Drowned flow conditions Subclause2 – 10.4\ufffd\ufffd\ufffd Accuracy UntitledSubclause3 – 10.4.1\ufffd\ufffd\ufffd The overall accuracy of measurement will depend on the following: UntitledSubclause3 – 10.4.2\ufffd\ufffd\ufffd The uncertainties ( <\/td>\n<\/tr>\n | ||||||
| 34<\/td>\n | Clause1 – 11\ufffd\ufffd\ufffd Uncertainties in flow measurement Subclause2 – 11.1\ufffd\ufffd\ufffd General UntitledSubclause3 – 11.1.1\ufffd\ufffd\ufffd The uncertainty of any flow measurement can be estimated if the un… UntitledSubclause3 – 11.1.2\ufffd\ufffd\ufffd The error in a result is the difference between the true rate of f… UntitledSubclause3 – 11.1.3\ufffd\ufffd\ufffd As far as is practicable this clause is in accordance with Subclause2 – 11.2\ufffd\ufffd\ufffd Sources of error <\/td>\n<\/tr>\n | ||||||
| 35<\/td>\n | Subclause2 – 11.3\ufffd\ufffd\ufffd Types of error UntitledSubclause3 – 11.3.1\ufffd\ufffd\ufffd Errors can be classified as random or systematic, the former affec… UntitledSubclause3 – 11.3.2\ufffd\ufffd\ufffd A measurement can also be subject to systematic error; the mean of… <\/td>\n<\/tr>\n | ||||||
| 36<\/td>\n | Subclause2 – 11.4\ufffd\ufffd\ufffd Errors in quantities given in this standard UntitledSubclause3 – 11.4.1\ufffd\ufffd\ufffd All the errors in this category are systematic. The values of the … UntitledSubclause3 – 11.4.2\ufffd\ufffd\ufffd However, when measurements are made on other similar installations… UntitledSubclause3 – 11.4.3\ufffd\ufffd\ufffd The probable uncertainties in the coefficients and the corrective … Subclause2 – 11.5\ufffd\ufffd\ufffd Errors in quantities measured by the user UntitledSubclause3 – 11.5.1\ufffd\ufffd\ufffd Both random and systematic errors occur in user measurements. UntitledSubclause3 – 11.5.2\ufffd\ufffd\ufffd Since neither the methods of measurement nor the way in which they… UntitledSubclause3 – 11.5.3\ufffd\ufffd\ufffd The uncertainty in the gauged head is determined from an assessmen… UntitledSubclause3 – 11.5.4\ufffd\ufffd\ufffd The above component uncertainties shall be calculated as percentag… Subclause2 – 11.6\ufffd\ufffd\ufffd Combination of uncertainty to give the overall uncertainty in discharge UntitledSubclause3 – 11.6.1\ufffd\ufffd\ufffd The uncertainty in discharge is given by the expression: UntitledSubclause3 – 11.6.2\ufffd\ufffd\ufffd The uncertainty in discharge is not a single value for a given dev… Clause1 – 12\ufffd\ufffd\ufffd Examples Subclause2 – 12.1\ufffd\ufffd\ufffd Modular flow at low discharge ( Subclause3 – 12.1.1\ufffd\ufffd\ufffd Data <\/td>\n<\/tr>\n | ||||||
| 37<\/td>\n | Subclause3 – 12.1.2\ufffd\ufffd\ufffd Solution by successive approximation method <\/td>\n<\/tr>\n | ||||||
| 38<\/td>\n | Subclause3 – 12.1.3\ufffd\ufffd\ufffd Solution by coefficient of velocity method Subclause3 – 12.1.4\ufffd\ufffd\ufffd Uncertainty in computed discharge Subclause2 – 12.2\ufffd\ufffd\ufffd Drowned flow at high discharge Subclause3 – 12.2.1\ufffd\ufffd\ufffd Data <\/td>\n<\/tr>\n | ||||||
| 39<\/td>\n | Subclause3 – 12.2.2\ufffd\ufffd\ufffd Solution using successive approximation method <\/td>\n<\/tr>\n | ||||||
| 40<\/td>\n | Subclause3 – 12.2.3\ufffd\ufffd\ufffd Solution using the coefficient of velocity method Subclause3 – 12.2.4\ufffd\ufffd\ufffd Uncertainty in computed discharge <\/td>\n<\/tr>\n | ||||||
| 41<\/td>\n | AnnexNormative – Velocity distribution UntitledClause1 – A.1\ufffd\ufffd\ufffd An even distribution of velocity over the cross-section of the approach … UntitledClause1 – A.2\ufffd\ufffd\ufffd Normal velocity distribution is defined as \u201cthe distribution of velociti… UntitledClause1 – A.3\ufffd\ufffd\ufffd Any deviation from the ideal conditions of either uniform or a normal ve… UntitledClause1 – A.4\ufffd\ufffd\ufffd In UntitledClause1 – A.5\ufffd\ufffd\ufffd The percentage difference in the value of <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Hydrometric determinations. Flow measurement in open channels using structures. Flat-V weirs<\/b><\/p>\n |