Browsing by Author "Jacobs, H. E."
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- 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.
- ItemConceptual framework for sewer pump problems allowing for fuzzy logic application(Water Research Commission, 2015-04) Bester, A. J.; Jacobs, H. E.; Tulleken, J.; Civil EngineeringSewer pump station problems in separate sewer systems (separate from stormwater drainage systems) were investigated in order to derive a conceptual framework for decision making. Notwithstanding the fundamental service that efficient sewage pumping provides to a community, it was apparent that limited research has been published on the topic. Research was undertaken to identify, investigate and classify problems at existing operational sewage pump stations by means of site visits, interviews, and an extensive knowledge review. A conceptual framework for sewer pump problems was subsequently derived. The application of the framework is illustrated by means of a fuzzy logic approach to one of the problem classes identified. This study sets the scene for further research into fuzzy-based efficiency indices pertaining to different sewer system components and the ultimate application in sewer system decision support tools.
- ItemCorrelating sound and flow rate at a tap(Elsevier, 2015-09) Jacobs, H. E.; Skibbe, Y.; Booysen, Marthinus J.; Makwiza, C.Laboratory tests were carried out to record the sound of water flowing through a tap and the corresponding flow rate. The results were analysed to determine a mathematical relationship between the sound signal and the flow rate. Three models, based on Fourier transforms of data in the frequency domain, were devised to estimate the flow rate of water as a function of the audible sound signal properties. The model was verified against independently recorded data from the experiments. An average error of 15% was determined when results were verified against 5 independently recorded data points. The hypothesis that actual flow rate could be estimated through the analysis of the recorded sound signal pattern was proven correct, but the accuracy of the results was relatively poor compared to mechanical meters. This study set the scene for further research into the use of microphones to assess outdoor water use.
- ItemPotable water use of residential consumers in the Cape Town metropolitan area with access to groundwater as a supplementary household water source(South African Water Research Commission, 2016-01) Jacobs, H. E.; Wright, T.The potable water use recorded by 3 579 residential consumer water meters in Cape Town, South Africa, was analysed as part of this research. The focus was on elected residential properties in serviced areas, with additional private access to groundwater as a supplementary household water source. Private consumers in South Africa are not normally required to report on, or meter, groundwater use. The research team analysed records of an extensive, compulsory registration process for supplementary on-site water sources that was introduced by the City of Cape Town during the prolonged drought between 2004 and 2005. The main objective of this research was to determine the average annual water demand of residential properties serviced via the potable water distribution system, with additional registered access to a supplementary on-site groundwater source. Geo-referencing was employed to determine the approximate coordinate of each property, with subsequent one-by-one verification of each address. The data set initially contained 4 487 properties, but after filtering and verification 3 579 consumers remained in the data set for further analyses. The unique property code was identified for each verified property in order to link the attributes of consumers with access to on-site groundwater sources to their corresponding water meter records, so that the potable water demand for these stands could be analysed. The annual average water demand of the properties was subsequently obtained and analysed for two separate periods, namely, 2010 and 2014. The water use, categorised according to stand size, was similar for both periods. The results showed that consumers with access to groundwater used only about 65% of the estimated average annual water demand when compared to applicable water demand guidelines.
- ItemResidential water information management(AOSIS OpenJournals, 2008-12) Jacobs, H. E.The hitherto undefined term 'water information management' (WIM) as it relates to residential water use is defined in this article as follows: 'To better manage the information pertaining to how and when water is used at home.' Effective WDM is based on effective WIM. This article underlines the importance of managing information, obtained from data, to manage water use. A review of residential water use, with a specific focus on end-uses of demand and information pertaining to it, is presented. Two types of data flow pertaining to water use at residential properties are identified. Type 1 information describes the monthly water use at a residential property recorded in the LA's financial billing system, while Type 2 information describes end-uses on a particular property. End-use models of water demand require Type 2 data as input, are renowned to be data hungry and are often arduous to populate. A method for populating the model parameters with a Web-based tool is also addressed. Success at gaining parameter values for end-use modelling via Web-based tools has been somewhat limited to date, but it is hoped that future improvements in simplifying the input requirement would lead to practical application. A former pilot study in CCT tested the capturing of input data, but did not extend beyond this somewhat limited functionality. Work is currently progressing on the international front to a point of practical application. It is hoped that application locally would soon follow suit. In addition to LAs and their demand management consultants gaining access to valuable end-use information with a Web-based tool, application of such a tool at household level would serve as a means for user education – home owners would learn more about their own water use, identify the most significant end-uses at home and be empowered to save water more effectively by focusing water saving efforts at 'the right' end-uses. In addition, the tool would provide valuable data inputs for research into end-use modelling of water use.