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The rating of sluicing flumes in combination with sharp-crested and crump weirs under modular and non-modular flow conditionsBruce, H. G. S. 12 1900 (has links)
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.
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Reliability assessment of a prestressed concrete memberBrand, W. W. (Willem Wouter) 12 1900 (has links)
Thesis (MScEng)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: First-order second-moment structural reliability methods are used to assess the reliability of
a prestressed concrete beam. This beam was designed for imposed office floor loads and
partitions following the limit states design method as provided for by the applicable South
African structural codes, viz SABS 0100-1:1992 and SABS 0160:1989.
The reliability is examined at two limit states. At the ultimate limit state of flexure the
ultimate moment of resistance must exceed the applied external moment at the critical section,
while at the serviceability limit state of deflection the deflection must satisfy the codespecified
deflection criteria. Realistic theoretical models are selected to express the flexural
strength and deflection of the prestressed concrete member, while appropriate probabilistic
models are gathered from the literature for loading, resistance and modelling uncertainties.
The calculated reliability index at the ultimate limit state of flexure (3.10) is lower than
expected in view of the fact that this represents a non-critical limit state in the case of a Class
2 prestressed concrete member. This condition can be explained with reference to the
relatively high uncertainty associated with the modelling error for flexural strength. The
calculated reliability index at the serviceability limit state of deflection (l.67) compares well
with acceptable practice.
The study further focuses on the sensitivity of the reliability at the two limit states of interest
to uncertainty in the various design parameters. The ultimate limit state of flexure is
dominated by the uncertainty associated with the modelling error for flexural strength, while
the contribution to the overall uncertainty of the ultimate strength and area of the prestressing
steel and the effective depth is less significant. In comparison the reliability at the
serviceability limit state of deflection is not dominated by the uncertainty associated with a
single basic variable. Instead, the uncertainty associated with the modelling error, creep factor
and prestress loss factor are all significant. It was also demonstrated that the variability in
beam stiffness is not a major source of uncertainty in the case of a Class 2 prestressed
concrete member.
It is recommended that the present code provisions for ultimate strength and deflection should
be reviewed to formulate theoretical models with reduced systematic and random errors. The
effect of the uncertainty associated with the creep and prestressed loss factors should also be
adressed by adjustment of the partial material factor for concrete at the serviceability limit
state of deflection. Furthermore, research must be directed towards formulating an objective
failure criterion for deflection. The uncertainty in the deflection limit must therefore be
quantified with a probability distribution. / AFRIKAANSE OPSOMMING: Eerste-orde tweede-moment struktuur betroubaarheid metodes word ingespan om die
betroubaarheid van 'n voorspanbeton balk te bereken. Hierdie balk is ontwerp vir opgelegte
kantoor vloerbelasting en partisies volgens die grenstoestand ontwerp metode soos beskryf in
die toepaslike Suid-Afrikaanse boukodes, naamlik SABS 0100-1: 1992 en SABS 0160: 1989.
Die betroubaarheid word ondersoek by twee grenstoestande. By die swiglimiet van buiging
moet die weerstandsmoment die eksterne aangewende moment oorskrei by die kritieke
balksnit, terwyl die defleksie die kriteria soos voorgeskryf deur die kode moet bevredig by
die dienslimiet van defleksie. Realistiese teoretiese modelle word gebruik om die buigsterkte
en defleksie van die voorspanbeton balk te bereken. Verder is geskikte waarskynlikheid
modelle uit die literatuur versamelom die belasting, weerstand en modelonsekerhede te
karakteriseer.
Die betroubaarheid indeks soos bereken vir die swiglimiet van buiging (3.10) is laer as wat
verwag sou word in die lig van die feit dat hierdie nie 'n kritieke grenstoestand
verteenwoordig in die geval van 'n Klas 2 voorspan element nie. Dit kan verklaar word met
verwysing na die relatiewe groot onsekerheid wat geassosieer word met die modellering fout
vir buigsterkte. Die berekende betroubaarheid indeks vir die dienslimiet van defleksie (1.67)
vergelyk goed met aanvaarde praktyk.
Die studie fokus verder op die sensitiwiteit van die betroubaarheid by die twee grenstoestande
onder beskouing ten opsigte van die onsekerheid in die verskillende ontwerp parameters. By
die swiglimiet van buiging word die onsekerheid oorheers deur die bydrae van die modelering
fout vir buigsterkte. Die bydraes tot die totale onsekerheid deur die swigsterkte en area van
die voorspanstaal sowel as die effektiewe diepte is minder belangrik. By die dienslimiet van
defleksie word die betroubaarheid nie oorheers deur die onsekerheid van 'n enkele basiese
veranderlike nie. In stede hiervan is die onsekerheid van die modellerings fout, kruipfaktor
en voorspan verliesfaktor almal noemenswaardig. Daar word verder aangetoon dat die
veranderlikheid in balkstyfheid nie 'n belangrike bron van onsekerheid in die geval van 'n
Klas 2 voorspan element is nie.
Daar word aanbeveel dat die bestaande voorskrifte in die kode vir buigsterkte en defleksie
aangespreek moet word deur teoretiese modelle met klein modelonsekerhede te formuleer.
Die uitwerking van die onsekerheid van die kruip- en voorspan verliesfaktore kan aangespreek
word deur 'n aanpassing te maak in die parsiële materiaalfaktor vir beton in die geval van die
dienslimiet van defleksie. Navorsing moet verder daarop gemik wees om 'n objektiewe
falingskriterium vir defleksie te formuleer. Die onsekerheid van die toelaatbare defleksie moet
dus gekwatifiseer word deur 'n waarskynlikheidsverdeling.
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Discharge measurement at natural controls in Western Cape riversBarnard, M. M January 2003 (has links)
Thesis (MEng)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: This study sets out to explore the possibilities and accuracy of flow measurement at
natural controls, focussing specifically on Western Cape cobble-bed rivers. These
rivers are regarded as being difficult in terms of flow measurement, mostly due to their
large scale roughness and very turbulent and uneven flows.
The aim is to determine a system through which various types of natural controls can be
calibrated, by establishing a relationship between the discharge coefficient and the
physical characteristics of each control type. This was achieved by conducting an
extensive field investigation, focussing on the identification and gauging of both critical
and uniform natural controls. Two types of critical controls were identified and
investigated, namely step-pool controls and horizontal constriction controls as well as
one type of uniform flow control, namely the plane bed control.
Step-pool controls were found to be very robust controls which provided efficient
critical controls for a wide range of flows. Horizontal constriction controls proved to be
reasonably accurate measurement sites and, because of their physical characteristics,
they are able to measure the full range of flows from low to flood flows. Uniform
controls are widely used for flow measurements on deep rivers, but such measurements
become highly unreliable when flow depths are small and bed roughness high as is the
case with cobble-bed rivers. Under conditions of high roughness, generally speaking
critical controls can be calibrated more accurately than uniform controls and are
therefore to be preferred.
The field study was followed by a series of laboratory tests, focussing on horizontal
constriction controls. Calibration equations were derived by which the discharge
coefficient value can be determined for a given constriction ratio and upstream energy
head. Results from both the fieldwork and laboratory work were analysed and integrated to
determine a calibration system applicable to natural controls in Western Cape cobbleand
boulder-bed rivers. Reasonably accurate values of the discharge coefficients for
different types of natural controls were established, which should be widely applicable.
Additionally, guidelines were drawn up for the measurement of flow at natural controls,
to be used by both engineers and non-engineers.
Discharge measurement at natural controls in the Western Cape was found to be a
viable and reasonably accurate way of determining river discharge. It proves to be an
environmentally acceptable way of measurement, using the natural river characteristics
rather than seriously interfering with them or damaging them. These advantages make
discharge measurement at natural controls a promising means of determining river
discharge in the future. / AFRIKAANSE OPSOMMING: Die beste posisie vir vloeirneting in riviere is waar die topografie van die rivier 'n
unieke verhouding tussen die deurstroming en die water diepte bewerkstellig.
Hierdie studie ondersoek die uitvoerbaarheid en akkuraatheid van vloeirneting by
natuurlike kontroles met die fokus op Wes-Kaapse spoelklip riviere. Vloeirneting in
spoelklip riviere word as baie ingewikkeld beskou weens die grootte van die
bedpartikels relatieftot die vloeidiepte en gevolglike onewe, turbulente vloeie.
Die doel van die studie was om 'n stelsel te ontwikkel waardeur verskillende tipes
natuurlike kontroles gekalibreer kan word deur verwantskappe te bepaal tussen die
deurstromings koëffisiënt en die stroom-op energie hoogte. Bogenoemde is bepaal met
behulp van 'n uitgebreide veldstudie waarin die hoof tipes natuurlike kontroles, nl. die
kritiese vloei kontrole en die uniforme vloei kontrole, geidentifiseer en gekalibreer is.
Twee tipes kritiese vloei kontroles is ondersoek, naamlik die trap-poel ("step-pool")
kontrole en die horisontale vernouing kontrole.
Daar is bevind dat beide die trap-poel kontrole en die horisontale vernouing baie
effektiewe kritiese kontroles is, waarmee 'n wye reeks van vloeie gemeet kan word.
Uniforme vloei kontroles word algemeen vir vloeimeting in diep vloeiende riviere
gebruik, maar sulke metings word hoogs onbetroubaar wanner die vloeidiepte klein is
relatief tot die partikel grootte van die rivierbed, soos in die geval van spoelklip riviere.
Onder hierdie omstandighede kan kritiese kontroles in die algemeen meer akkuraat
gekalibreer word en word hul gevolglik bo uniforme vloei kontroles verkies.
Die veldstudie is gevolg deur 'n reeks laboratorium toetse, wat fokus op die horisontale
vernouing kontrole. Kalibrasie vergelykings is afgelei waarmee die deurstromings
koëffisient vir 'n gegewe stroom-op energiehoogte en vernouings-verhouding bereken
kan word.
Resultate van beide die veldstudie en die laboratorium toetse is geanaliseer en
geïntegreer om 'n kalibrasie stelsel te bepaal wat van toepassing is op natuurlike kontroles in Wes-Kaapse spoelklip riviere. Aanvaarbare waardes vir die deurstromings
koëffisiente vir verskeie tipes natuurlike kontroles is bepaal, wat algemeen toepasbaar
behoort te wees.
Riglyne vir die meting van riviervloei by natuurlike kontroles is opgestel vir die gebruik
deur beide ingenieurs en nie-ingenieurs.
Vloeimeting deur middel van natuurlike kontroles is 'n lewensvatbare metingsmetode
waarmee riviervloei redelik akkuraat bepaal kan word. Dit is 'n omgewingsaanvaarbare
metings metode wat die natuurlike karakter van die rivier gebruik, eerder as
om ernstig daarmee in te meng of dit te beskadig. Hierde positiewe eienskappe maak
vloeimeting deur middel van natuurlike kontroles 'n belowende metingsmetode vir die
toekoms.
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Verification of the inlet capacities of modified stormwater kerb inlets and the development of new design curvesGrobler, Pieter 03 1900 (has links)
Thesis (MEng)--Stellenbosch University, 1994. / ENGLISH ABSTRACT: Various aspects affecting the inlet capacities of modified stormwater kerb inlets were
investigated. Investigations centred on the influence of effective inlet length, ratios of
upstream transition section length to inlet section length and road crossfall. The
suitability of existing design curves for use in the design of modified kerb inlets was
verified and new more "user-friendly" design curves were developed. Attempts were
made to develop a sound theoretical model to predict inlet capacities for stormwater
kerb inlets as the lack of such a model had previously been identified as a major
shortcoming in the design of stormwater kerb inlets.
A detailed study of relevant literature and of various full scale model test results
confirmed the fact that the effective inlet length is the most important variable
affecting the inlet capacity at stormwater kerb inlets. Model studies on various
combinations of transition section lengths and inlet section lengths have indicated that
in the case of supercritical flow the inlet capacity of stormwater kerb inlets is not
sensitive to changes in the ratio between the inlet section length and the upstream
transition section length. Furthermore no marked effect on the inlet capacity of a
modified stormwater kerb inlet was detected when the road crossfall was increased
from 2% to 3%. The inlet capacities predicted by the existing design curves were
found to be consistent, although on the conservative side, when compared to the inlet
capacities obtained from the full scale model tests. New design curves derived from
the existing design curves were developed to provide a less cumbersome procedure in
the design of stormwater kerb inlets. The development of an improved comprehensive
theoretical model based on pure hydraulic principles was not possible due to the
extremely complex nature of flow conditions at stormwater kerb inlets. The most important findings emanating from this research project are: - The confirmation of the "effective inlet length” concept, whereby a part of the expensive inlet section is replaced by an equivalent length of inexpensive transition section upstream of the kerb inlet. which does not affect the inlet capacity of the kerb inlet negatively and thereby results in a substantial saving
in the cost of stormwater kerb inlets. - Model tests revealed that for supercritical flows the upstream transition section
can be made up to 6 times longer than the inlet section with a maximum length
of 6m. without any negative effect on the inlet capacity of the kerb inlet.
Similarly an analysis of previous research results has indicated that even in
cases of subcritical flow the upstream transition section can be made twice the
length of the inlet section. - The full scale model tests also indicated that an upward adjustment of 30% in
the inlet capacities as predicted by the existing design curves was justified. The
modified design curves proved to be suitable for the design of conventional
stormwater kerb inlets as well as for modified stormwater kerb inlets where
part of the inlet section is replaced by a transition section. A new set of "easy
to use" design curves was developed specifically for urban applications. - Guidelines for determining upstream transition section lengths were drawn up
for use in conjunction with the existing and new design curves for the design
of stormwater kerb inlets. / AFRIKAANSE OPSOMMING: Verskeie aspekte wat die inlaatkapasiteit van verbeterde randsteeninlate belnvloed is
ondersook. Die belangrikste aspekte wat ondersoek is, was die invlood van effektiewe
inlaatlengte en die moontlike verhouding van die stroomop oorgangslengte tot die
werklike inlaatlengte sowel as dwarshelling. Die ontwerpgrafieke wat tans gebruik
word om randsteeninlaatlengtes te bepaal is ook ondersoek aan die hand van
modeltoetse op volskaalse modelle om die grafieke se akkuraatheid te toots. Meer
gebruikersvriendelike ontwerpgrafieke is ook ontwikkel. 'n Belangrike tekortkoming
tot op datum, naamlik 'n geskikte teoretiese model om die inlaatkapasiteit van
randsteeninlate te beskryf, is aangespreek. 'n Voorvereiste vir so 'n model was dat die
model gebaseer moes word op suiwer hidrouliese beginsels.
Die bestudering van vorige navorsing asook die uitvoering van verskeie modelstudies
op volskaalse randsteeninlate het die effektiewe inlaatlengte as die belangrikste
veranderlike wat die inlaatkapasiteit van randsteeninlate bepaal geYdentifiseer. Tydens
tootse uitgevoer op volskaalse modelle onder superkritiese vlooitoostande met
verskillende kombinasies van oorgangslengtes en inlaatlengtes, vir die dieselfde totale
lengte het dit geblyk dat die inlaatkapasiteit grootliks onatbanklik is van die
verhouding van die oorgangslengte tot die inlaatlengte. Vit die modeltootse het dit oak
geblyk dat paddwarsval 'n baie beperkte invlood op die inlaatkapasiteit van
ransteeninlate gehad het toe die paddwarsval verander is van 2%na 3%. Die resultate
wat verkry is uit die modeltoetse het ook aangetoon dat die bestaande ontwerpgrafieke
konserwatief is in hul voorspelling van inlaatkapasieit van randsteeninlate. Die
bestaande ontwerpgrafieke is voorts gebruik om nuwe meer gebruikersvriendelike
ontwerpgrafieke te ontwikkel. Die ontwikkeling van 'n teoretiese model am
inlaatkapasiteite volledig te voorspel was egter nie moontlik nie vanwee die uiters
komplekse aard van die vloei by randsteeninlate.
Die belangrikste bevindinge van hierdie studie kan soos volg opgesom word: - Afdoende bewyse is gevind dat die "effektiewe inlaatlengte" konsep,
waarvolgens 'n gedeelte van die duur inlaatgedeelte met 'n goedkoper
oorgangsstuk van dieselfde Iengte vervang kan word sonder om inlaatkapasiteit
in te boet, weI suksesvol aangewend kan word om kostes in die ontwerp van
stOlIDwater randsteeninlate te bespaar. - Afdoende bewyse is gevind dat die "effektiewe inlaatlengte" konsep,
waarvolgens 'n gedeelte van die duur inlaatgedeelte met 'n goedkoper
oorgangsstuk van dieselfde Iengte vervang kan word sonder om inlaatkapasiteit
in te boet, weI suksesvol aangewend kan word om kostes in die ontwerp van
stOlIDwater randsteeninlate te bespaar. - Afdoende bewyse is gevind dat die "effektiewe inlaatlengte" konsep,
waarvolgens 'n gedeelte van die duur inlaatgedeelte met 'n goedkoper
oorgangsstuk van dieselfde Iengte vervang kan word sonder om inlaatkapasiteit
in te boet, weI suksesvol aangewend kan word om kostes in die ontwerp van
stOlIDwater randsteeninlate te bespaar. - Riglyne is ook ontwikkel vir die bepaling van stroomop oorgangslengtes. Die
riglyne kan saam met die bestaande en die nuwe ontwerpgrafieke gebruik word
by die ontwerp van stormwater nmdsteeninlate.
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Investigation of turbidity and chlorine disinfection in South African waters.19 October 2010 (has links)
All natural waters containing particulate matter, such as clay, silt, colloidal particles, plankton / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2007
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Long term emission from pre treated waste : column studies.20 October 2010 (has links)
Emissions resulting from waste degradation processes have a high polluting potential / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2006.
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Stabilisation of waste in shallow test cells : focus on biogas.Chetty, Nevendra Krishniah. January 2006 (has links)
Present day society generates large volumes of waste that present an environmental hazard when disposed of in landfills. As our population grows, so does the volume of waste generated and hence the threat to our environment. One method of reducing harmful emissions in landfills is the mechanical-biological pretreatment of waste prior to landfilling. The purpose of this dissertation is to investigate the degree of stabilization of waste in shallow landfills (simulated by test cells) with particular focus on biogas production and quality. Municipal waste was composted in aerobic, open windrows for periods of eight and sixteen weeks. Five test cells, designed and operated according to the PAF model (Pretreatment, Aeration and Flushing) were constructed at the Bisasar Road landfill site. These cells were used to simulate large scale municipal landfill sites. They were filled with fresh and pretreated waste and were used to monitor the dynamics of prolonged aeration and degradation of waste over a period of six months. The cells were monitored on a weekly basis while being aerated. Two flushing events were conducted at the beginning of the passive aeration. Gas emissions were also monitored by recording the methane, carbon dioxide and oxygen volumes per volume of air in probes strategically placed in each cell. These results were then analysed to assess the effect of mechanical-biological pretreatment of municipal solid waste on the emission quality of sanitary landfills and the appropriateness of prolonging the aeration in shallow landfills, as often used in sub-tropical countries. It was found that the design of the test cells was appropriate for the landfilling and stabilization of waste that was aerobically treated. After six months in the test cells, analysis of the waste from each cell showed that the waste was completely degraded. The PAF model, when applied to shallow landfills, is very effective in stabilising waste and would be appropriate for a sub-tropical climate. Waste that is pretreated, placed in shallow landfills, initially flushed and then aerated over a six month period was fully stabilized. The requirement for such treatment would be relatively small amounts of waste, a wet climate and the availability of open space for shallow landfills. This method, therefore, would be very appropriate in a South African context. The major problem with this method may be the generation of large quantities of leachate which will have to be treated and disposed of in an environmentally safe manner. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2006.
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The study of the kinetics of degradation of mechanical-biological pretreated waste using test cells.02 November 2010 (has links)
This research was carried out at the Bisasar Road Landfill site, Durban, South Africa, / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2007.
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Environmental impacts of the construction phase of an intensive development project on a coastal forest wetland : case study : Seaward Estates, Ballito.14 January 2011 (has links)
Storm water runoff is a leading cause of degradation in the water quality of receiving
water bodies. Although legislation requires that Environmental Impact Assessments
(EIA) are performed and Environmental Management Plans (EMP) put in place for the
construction of high density housing developments, there is generally very little
evidence that real measures are developed to monitor and actually assess the extent
of the impact that construction activities have on the environment during the physical
construction stage.
The water quality of stormwater runoff from a mixed use catchment including
construction sites in Seaward Estates, Ballito, KwaZulu-Natal that enters a coastal
forest wetland system was characterised by monitoring programmes established at
three study areas. The effect thereof on the quality of the wetland water and sediments
was further monitored at five points along the drainage line of the system. The
investigation focussed on obtaining representative stormwater samples in order to
quantitatively identify pollutant constituents transported within stormwater runoff from
construction sites during rainfall events.
Storm water runoff event mean concentration (EMC), atmospheric deposition and
wetland water and sediment samples were collected over an eight month period. The
characterisation of stormwater runoff for this investigation included heavy metals,
oxygen demanding substances, sediments and physico-chemical analysis for pH,
conductivity and ammonia and nitrates. The majority of contaminant EMC exceeded
the South African wastewater discharge general and special limits.
The findings from this investigation will provide planners and decision-makers with a
greater understanding of the pollution dynamics of construction sites aiding in improved
best management practice decisions with regard to minimizing impacts on coastal
forest wetlands and water resources. This will lead to improved EMP and stormwater
management plans (SWMP) incorporating stormwater pollution prevention plans
(SWPPP) for construction sites. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2007.
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Spatio-temporal rainfall estimation and nowcasting for flash flood forecasting.Sinclair, Scott January 2007 (has links)
Floods cannot be prevented, but their devastating effects can be minimized if advance warning of the event is available. The South African Disaster Management Act (Act 57 of 2002) advocates a paradigm shift from the current "bucket and blanket brigade" response-based mind set to one where disaster prevention or mitigation are the preferred options. It is in the context of mitigating the effects of floods that the development and implementation of a reli able flood forecasting system has major significance. In the case of flash floods, a few hours lead time can afford disaster managers the opportunity to take steps which may significantly reduce loss of life and damage to property. The engineering challenges in developing and implementing such a system are numerous. In this thesis, the design and implement at ion of a flash flood forecasting system in South Africa is critically examined. The technical aspect s relating to spatio-temporal rainfall estimation and now casting are a key area in which new contributions are made. In particular, field and optical flow advection algorithms are adapted and refined to help pred ict future path s of storms; fast and pragmatic algorithms for combining rain gauge and remote sensing (rada r and satellite) estimates are re fi ned and validated; a two-dimensional adaptation of Empirical Mode Decomposition is devised to extract the temporally persistent structure embedded in rainfall fields. A second area of significant contribution relates to real-time fore cast updates, made in response to the most recent observed information. A number of techniques embedded in the rich Kalm an and adaptive filtering literature are adopted for this purpose. The work captures the current "state of play" in the South African context and hopes to provide a blueprint for future development of an essential tool for disaster management. There are a number of natural spin-offs from this work for related field s in water resources management. / Thesis (Ph.D.Eng.)-University of KwaZulu-Natal, Durban, 2007.
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