Thesis (MEng)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: As part of a previous WRC project, three types of sluicing flumes were developed for
use in compound weirs in combination with sharp-crested and crump weirs, (Rossouw
et al., 1998). These sluicing flumes have several advantages which make them ideal
structures for flow measurement in South African rivers. These are a high modular
limit, stable modular flow characteristics, an ability to measure a wide range of flows
accurately, as well as good sediment handling characteristics. These three flumes have
been calibrated under modular or free flow conditions in combination with sharpcrested
and crump weirs.
There is a high degree of variability of flow in South African rivers. Flood discharges
are part of this variability, and can form an important part of the mean annual runoff.
Measuring weirs cannot always be built so that they do not become submerged during
floods, but it is nevertheless important that flood discharges be recorded. It is
therefore important that these compound weirs be calibrated for flow measurement
under non-modular or submerged conditions.
The purpose of the research undertaken for this WRC project is to find a method to
calculate the non-modular discharge over compound weirs consisting of sluicing
flumes in combination with sharp-crested and crump weirs.
By analysis of existing data from the previous WRC project, as well as data from
laboratory tests undertaken as part of this project, the submergence effect of sluicing
flumes has been quantified. A range of configurations of sharp-crested weirs as well
as crump weirs in combination with the sluicing flume have been tested. A new
method has been developed to calculate the submerged discharge over these
compound weirs. This method is suitably accurate, and can be recommended to the
DWAF for use.
The calculation procedure that must be followed in order to calculate the submerged
discharge over these compound weirs becomes rather complicated due to the
iterations that must be carried out. In order to clarify these procedures, flow charts are
provided which set out the steps that must be followed.
Calibration curves for all the combinations of compound weirs analysed in this report
are also provided. These can be used to obtain estimates of the discharge in the field,
and can also be used as a check on any calculations carried out.
The principal goal of this project, namely that of finding a suitably accurate method to
calculate the non-modular discharge over these compound weirs has therefore been
achieved. / AFRIKAANSE OPSOMMING: As deel van 'n vorige Water Navorsings Kommisie (WNK) projek, is drie spoelgeute
ontwikkel vir gebruik in saamgestelde meetwalle in kombinasie met skerp-kruin en
Crump oorlope, (Rossouwet al., 1998). Die spoelgeute het eienskappe wat hulle
gunstig maak vir vloeimeting in Suid Afrikaanse riviere. Vanhierdie eienskappe is 'n
hoë modulêre limiet, stabiele modulêre vloei eienskappe, goeie sediment hanterings
eienskappe en 'n vermoë om oor 'n wye bereik vloeie akkuraat te kan meet. Hierdie
drie geute is in kombinasie met skerpkruin en Crump oorlope gekalibreer onder vryvloei
toestande.
Vloeie varieër baie in Suid Afrikaanse riviere. Vloede is deel van hierdie variasies en
maak 'n belangrike deel uit van die gemiddelde jaarlikse afloop. Meetwalle kan nie
altyd gebou word sodat hulle nie versuip tydens vloede nie, maar dit is nogtans
belangrik dat hierdie vloeie gemeet word. Daarom is dit belangrik dat saamgestelde
meetwalle gekalibreer is vir vloeimeting onder versuipte of nie-modulêre toestande.
Die doel van die navorsing wat gedoen is vir hierde WNK projek was om 'n geskikte
metode te ontwikkel om die nie-modulêre vloeie oor saamgestelde meetwalle, wat
bestaan uit spoelgeute in kombinasie met skerpkruin en Crump oorlope, te kan
bereken.
Met die analise van bestaande data van die vorige WNK projek, asook data van
labratoriumtoetse wat gedoen is as deel van hierdie projek, is die versuiping van
spoelgeute beskryf. 'n Hele reeks skerpkruin asook crump oorlope is getoets in
kombinasie met die spoelgeute. 'n Nuwe metode is ontwikkel om die nie-modulêre
vloei oor hierdie saamgestelde meetstrukture te kan bereken. Hierdie metode IS
akkuraat genoeg om aan die Departement van Waterwese te kan aanbeveel.
Die berekingsproses wat gevolg moet word om die versuipte vloei oor die
saamgestelde meetstrukture te bereken, raak ingewikkeld as gevolg van die iterasies
wat uitgevoer moet word. Vloeidiagramme is opgestel wat hierdie prosedures duidelik
uiteensit.
Kalibrasie kurwes is ook ontwikkel vir al die kombinasies van saamgestelde
meetwalle wat geanaliseer is in hierdie verslag. Hierdie kurwes kan gebruik word om
skattings te maak van vloeie in die veld, maar ook om enige berekings wat gedoen is
te kontroleer.
Die hoofdoel van hierdie projek, naamlik om 'n geskikte metode te ontwikkel wat die
nie-modulêre vloeie oor saamgestelde meetwalle akuraat kan bereken, is bereik.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52006 |
| Date | 12 1900 |
| Creators | Bruce, H. G. S. |
| Contributors | Rooseboom, A., Rossouw, J., Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 1 v. (various pagings) : ill. |
| Rights | Stellenbosch University |
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