Browsing by Author "Jacobs, Heinz Erasmus"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    A conceptual index for benchmarking intermittent water supply in a water distribution system zone
    (Water Research Commission, 2020-01) Loubser, Carlo; Basson, Suzanne Esther; Jacobs, Heinz Erasmus
    Various challenges, such as limited freshwater resources, climate change impacts, rapid population growth, urbanisation and underinvestment in water supply infrastructure, have led to intermittent water supply (IWS) in potable water distribution systems. Earlier research has confirmed that IWS negatively impacts the consumers, the infrastructure and the water supply authorities. Water supply authorities need tools to help understand IWS and the associated implications. A new indexing framework involving the causes and impacts associated with IWS is presented in this paper. In addition, a novel approach allows for quantification of the severity of IWS based on knowledge of a few readily available inputs. The severity quantification is based on two ratios: the intermittency ratio is a temporal measurement, accounting for supply duration; the connection ratio describes spatial aspects, using the number of service connections affected. The indexing framework and quantification tool could lead to improved understanding of IWS and could assist water supply authorities faced with IWS to make informed decisions. Improved planning of remedial actions to mitigate or avoid risks associated with IWS is aided. The tools presented in this paper could be used as basis for future development of a key performance indicator.
  • Thumbnail Image
    Item
    A conceptual theoretical framework to integrally assess the possible impacts of climate change on domestic irrigation water use
    (South African Water Research Commission, 2015-10) Jacobs, Heinz Erasmus; Houssa, Fadoua; Fuamba, Musandji; Makwiza, Chikondi
    Southern Africa is likely to experience higher evapotranspiration and altered rainfall characteristics due to global warming and climate change. Climate-driven water use may potentially stress water supply facilities due to increased demand and reduced surface water yield. This paper presents a conceptual theoretical framework for assessing impacts of climate change on domestic irrigation water use. The prediction of climatic conditions that may potentially influence future water use is reviewed together with regional capacity for downscaling global climate projections. The impact assessment of water use is based on the modification and adaptation of an existing end-use model for water demand to include parameters for climate change. The Penman-Monteith equation and the soil water balance equation are incorporated for the estimation of daily water needs of vegetated areas in residential properties. The paper also discusses data requirements and a calibration procedure to improve model fit to the observed domestic irrigation water use. The proposed approach could form a basis for constructing a detailed model for planning various adaption measures relating to climate-driven domestic irrigation water use.
  • Thumbnail Image
    Item
    Garden irrigation as household end-use in the presence of supplementary groundwater supply
    (South African Water Research Commission, 2019-05) Meyer, Bettina Elizabeth; Jacobs, Heinz Erasmus
    ENGLISH ABSTRACT: Garden irrigation is a significant and variable household water end‑use, while groundwater abstraction may be a notable supplementary water source available in some serviced residential areas. Residential groundwater is abstracted by means of garden boreholes or well points and – in the study area – abstracted groundwater is typically used for garden irrigation. The volume irrigated per event is a function of event duration, frequency of application and flow rate, which in turn are dependent on numerous factors that vary by source – including water availability, pressure and price. The temperature variation of groundwater abstraction pipes at residential properties was recorded and analysed as part of this study in order to estimate values for three model inputs, namely, pumping event duration, irrigation frequency, and flow rate. This research incorporates a basic end‑use model for garden irrigation, with inputs derived from the case study in Cape Town, South Africa.  The model was subsequently used to stochastically evaluate garden irrigation. Over an 11-d period, 68 garden irrigation events were identified in the sample group of 10 residential properties. The average garden irrigation event duration was 2 h 16 min and the average daily garden irrigation event volume was 1.39 m³.
  • Thumbnail Image
    Item
    Supplementary 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, Kobus
    ENGLISH 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.