Browsing by Author "Nel, Nicole"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
- ItemBaseline adjustment methodology in a shared water savings contract during severe water restrictions - a case study in the Western Cape, South Africa(2020-01) Jacobs, H. E.; Du Plessis, J. L.; Nel, Nicole; Gugushe, S.; Levin, S.A novel method for baseline adjustment in a shared water savings contract under serious drought conditions was presented in a companion paper. The newly developed baseline adjustment method was subsequently applied to a case study, as discussed in this manuscript. The case study involved application of the method to 24 relatively complex sites, spread over the Western Cape Province in South Africa. The sites included, for example, military bases, naval dockyards, an airforce base, prison facilities, large multi-storey blocks of flats and administrative office buildings. Baseline adjustment became essential mid-contract during the serious water restrictions in Cape Town at the time. The restrictions were linked to the 'Day Zero' scenario in 2018 when water supply would potentially run out, and resulted in water savings at baseline sites that were ascribed to external factors. The study incorporated a comprehensive review of the approved baseline reports with site visits to 12 of the properties. The baseline adjustment method provided a robust means to obtain adjustments for sites with relatively limited data. The minimum data requirement was a record of monthly water consumption per site. The adjustments varied between 0% and 64% of the original baseline value for the different sites in the study sample. The relatively higher adjustments were linked to sites where outdoor irrigation and pool water use was prevalent during the baseline-setting period, but was banned during the drought. Zero adjustments were found for sites with exceptionally high leakage flows that had subsequently been repaired; leaks dwarfed actual use in these cases. The results for all 24 sites were accepted by the contracting parties as being reasonable and fair.
- ItemBaseline adjustment methodology in a shared water savings contract under serious drought conditions(Water Research Commission, 2020-01) Jacobs, H. E.; Du Plessis, J. L.; Nel, Nicole; Gugushe, S.; Levin, S.ENGLISH ABSTRACT: Baselines are often employed in shared water saving contracts for estimating water savings after some type of intervention by the water service company. An adjustment to the baseline may become necessary under certain conditions. Earlier work has described a number of relatively complex methods for baseline determination and adjustment, but application in regions faced with relatively limited data becomes problematic. If the adjustment were determined before finalising the contractual matters, it would be possible to gather the required data in order to determine the adjustment. However, in cases where no adjustment was fixed prior to the contract, a method is required to determine an adjustment mid-contract based on whatever data are available at the time. This paper presents a methodology for baseline adjustment in an existing shared water savings contract and explains how adjustment could be determined mid-contract, under conditions of limited data. The adjustment compensates for expected reduced water consumption due to external influences induced by serious water restrictions, typically introduced during periods of drought. The fundamental principle underpinning the baseline adjustment methodology presented in this paper involved segregating real water losses from the actual consumption of end-users, preferably by analysing the minimum night flow. In the absence of recorded night flows, an alternative procedure involving the minimum monthly consumption pre- and post-baseline was employed. The baseline adjustment method was subsequently applied in a South African case study, reported on separately. This technique is helpful because adjustments could be determined without adding unnecessary complexity or cost, and provides a means to resolve disputes in cases where unexpected savings occur mid-contract.
- ItemAn investigation into untreated greywater as supplementary household water source to augment potable municipal supply with consideration of associated risks.(Stellenbosch : Stellenbosch University, 2022-04) Nel, Nicole; Jacobs, Heinz Erasmus; Brink, Isobel; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.ENGLISH ABSTRACT: Despite the available body of research regarding supplementary household water sources and in particular, greywater use, there is a critical gap when it comes to understanding the uptake of untreated greywater in suburban areas and the trade-off between the risks and potential water savings. This dissertation focuses on untreated greywater use in residential, fully serviced houses equipped with regular water use appliances and with conventional waterborne sewers. The main objective is to gain an improved understanding of the uptake of untreated greywater and the potential for use and application in suburban areas by exploring the trade-off between expected water savings (associated with quantity) and potential risks (associated with quality) as related to untreated greywater use. This study starts with addressing on-site supplementary household water sources with a focus on groundwater abstraction, rainwater harvesting, and greywater use as available non-potable supplementary water sources to residential consumers. The legal position in South Africa and an end use model to assess the theoretical impact of these sources on water demand in formal residential areas, is presented. The model provides valuable strategic direction and indicates a significant theoretical reduction in potable municipal water demand of between 55% and 69% for relatively large properties with irrigated gardens when supplementary household sources are maximally utilised (when compared to exclusive municipal use as a baseline). This load reduction on piped reticulation systems could be an advantage through augmenting municipal supply. However, water service planning and demand management are complicated by the introduction, and possible future decommissioning, of any household water source. The trade off between the advantages and disadvantages of this load reduction defines whether there is a nett positive benefit linked to the use of the household water sources. Groundwater is the household water source considered to have the most notable penetration and intensity to impact potable water demand in residential areas and is coupled to a relatively low risk in terms of water quality relative to other uses such as greywater use. Groundwater, however, has the biggest barrier to entry and requires the highest capital investment of the three supplementary household water sources. The distinct trade off between the advantages and disadvantages of untreated greywater, particularly in comparison to the other supplementary household water sources, provides justification towards it being the focus of this study. Untreated greywater use at household level is an accessible water source to supplement non-potable water requirements in times of emergency water curtailments, but poses various risks to the consumer, the wider community, infrastructure and the environment. Little is known about unregulated, untreated greywater use practices in suburban communities where consumers have become accustomed to reliable potable water supplied via a pressurised, piped distribution system. There is a lack of knowledge regarding the sources of greywater used, collection methods, -storage and -distribution, the application points, the level of treatment (if any) and the perceived risks related to the greywater use. The City of Cape Town was selected as a case study site for research into greywater use under the threat of “Day Zero” and stringent water restrictions, implemented during the 2017/2018 summer season. A consumer survey and analysis of relevant online forums was conducted in order to obtain the necessary information. Greywater use practices from a sample group of 351 consumers were identified and classified. Untreated greywater use was found to be common, mainly for garden irrigation and toilet flushing. The results point to high-risk activities in the study group. By using these reported ad hoc greywater use practices identified through the Cape Town case study, the volume of untreated greywater used by households in formal residential settings was evaluated by means of a stochastic end use model. Untreated greywater use practices (e.g. bucketing) were found to reduce water consumption in a single person suburban household by less than 10%, which is lower than values reported in literature. This relatively low volume weighed up against the high risk of using untreated greywater may result in a negative nett benefit, providing decision making insights for both water service providers and consumers. This quantification of the volumes associated with untreated ad hoc greywater use is the first step in understanding the trade-off between expected water savings (quantity) and potential risks (quality) of untreated greywater use. The second component of the water saving-risk trade off involved an investigation of untreated greywater quality and related risks, through a statistical analysis of greywater quality results, as sourced from South African studies. Greywater sources included were the bathroom, kitchen, laundry, mixed and general residential sources. Variability in terms of each of the reported physical, chemical and microbiological constituents by source and between result sets was noted. Statistically significant differences were evident between the pH, conductivity and phosphorous values of certain sources. A risk assessment undertaken for each of the constituents revealed further variability. The constituent with the highest number of high-risk samples was total dissolved solids, although further research into specific constituent elements that are of real danger to humans is warranted here. The finding that water savings due to untreated greywater through manual collection methods is <10% is markedly less than the water savings through the use of multiple household water sources (up to 69% for large properties). This coupled with the relatively high risk and high consequences in greywater practices in terms of public health, the environment, and infrastructure, given its variability, provide insight into the quality-quantity space. There is a need for a more nuanced view of the potential potable savings associated with greywater use and a need for improved risk management. Risk management and drivers of consumer decision making in the water use space were therefore explored further. As a result, a decision-making matrix was designed as an interim conceptual tool to assist consumers when faced with water use decisions during emergency drought conditions. This research is unique in that while the use of greywater with purpose-built infrastructure and treatment systems has been studied for a number of locations and configurations, the practices used by individuals in the absence of such infrastructure was not well understood. This study has shed light on the reported volume of untreated greywater used by households in formal residential settings, based on reported ad hoc greywater use practices and on the extent of these potentially risky practices. A novel holistic picture of the risks and trade-offs associated with untreated greywater use was developed, allowing for advancement of knowledge in the field.
- ItemPrevalence of maternal tachycardia during late pregnancy(Stellenbosch : Stellenbosch University, 2012-12) Nel, Nicole; Odendaal, H. J.; Stellenbosch University. Faculty of Medicine and Health Sciences. Dept. of Interdisciplinary Health Sciences. Nursing Science.ENGLISH ABSTRACT: The importance of maintaining maternal wellbeing during the antenatal period is mandatory to the mother and the baby. Although asymptomatic maternal tachycardia could be seen as part of the physiological changes during pregnancy, it could also be a sign of a serious underlying condition. Previous studies have shown that maternal deaths could occur in women with pre-existing cardiac conditions (Naidoo, Desai & Moodley, 2002:17). The concern that many conditions associated with maternal tachycardia pass through the health care system without being noticed or investigated motivated the researcher to undertake this study. The study aimed to determine the prevalence of maternal tachycardia during late pregnancy and its association with anaemia, major cardiac diseases and/or complications and adverse maternal and perinatal outcomes. A case-control retrospective study design within a prospective study was employed with a quantitative approach. A total sample size of 204 participants, constituting 14.3% of the study population (N=1431) was purposefully selected from the Monica AN24™ recordings of the Safe Passage Study at Tygerberg Hospital to collect the data. Ethical approval was obtained from the Health Research Ethics Committee of the Faculty of Medicine and Health Sciences, Stellenbosch University and a waiver of consent had been granted. A group of 16 participants, who met the inclusion criteria, constituting 7.8% of the total sample, was selected for the pilot study. Reliability and validity was ensured by the pilot study and pre-testing the data collection instrument as it was tested under the exact circumstances as the actual study experts in the field of nursing and medical research and statistics were used. The data was analyzed by the use of the STATISTICA version 9 programme. The results show a 7.1% (n=102) prevalence of maternal tachycardia in late pregnancy. There were no pre-existing cardiac conditions in any of the groups and no maternal cardiac complications during pregnancy and delivery. The case group had a higher incidence (55.0%) of haemoglobin values lower than 11.0 g/dL than the control group (47.0%), however the Mann-Whitney U test revealed no statistically significant difference of the Hb values at 28 to 38 weeks between the case and the control groups. The participants presenting with anaemia (Hb < 11.0 g/dL) were classified as mild anaemia (Hb value of 7.0 – 10.9 g/dL). There were no participants that presented with severe anaemia (Hb value of < 7.0g/dL). There was an increased prevalence (9.1%) of infection in the participants presenting with maternal tachycardia, although this difference was not significant between the two groups. The infant outcome revealed an increased mean birth weight of 194g for the case group that presented with maternal tachycardia. Several recommendations were identified that were grounded in the study findings. The findings reveal that the current antenatal care practice in terms of not recording the maternal heart rate is sufficient.
- ItemSupplementary household water sources to augment potable municipal supply in South Africa(South African Water Research Commission, 2017-10) Nel, Nicole; Jacobs, Heinz Erasmus; Loubser, Carlo; Du Plessis, KobusENGLISH ABSTRACT: This paper addresses on-site supplementary household water sources with a focus on groundwater abstraction, rainwater harvesting and greywater reuse as available non-potable water sources to residential consumers. An end-use model is presented and used to assess the theoretical impact of household water sources on potable water demand in formal residential areas. Reliable potable municipal supply to urban consumers via the water distribution system is typically linked to relatively low uptake of household water sources. However, stringent water restrictions in some large South African cities that prohibit outdoor use, and reports of intermittent water supply, have led to increased uptake of household sources in South Africa. This paper describes the legal position regarding such sources in South Africa, and describes an end-use model to assess the theoretical impact on water demand in formal residential areas. The model provides valuable strategic direction and indicates a significant theoretical reduction in potable municipal water demand of between 55% and 69% for relatively large properties when household sources are maximally utilised (when compared to exclusive unrestricted municipal use as a baseline). This load reduction on piped reticulation systems could be an advantage in order to augment municipal supply, but water service planning and demand management are complicated by the introduction, and possible future decommissioning, of any household water source. The extent of both positive and negative impacts of household water sources requires further research.