19.11 Transfer of water outside of region
a. Transfer of water outside of region
The volume reported (4,053 ML) represents potable water supplied to users outside the Adelaide region from the Barossa, Onkaparinga Summit Storage and Myponga water treatment plants (WTPs). The following table details the volume of potable water exported during the 2012–13 year from each respective WTP.
|Summit Storage (Onkaparinga)||2,586|
b. Urban water system overview
The urban water supply system is one of three subcomponents of Adelaide's urban water system. The three subcomponents are the:
- urban water supply system
- wastewater system
- recycled water system.
During the 2012–13 year, Adelaide's urban water supply system relied on three important water sources. Imported River Murray water (line item 11.9 Delivery of water to urban water system under inter-region agreement) and surface water harvested from catchments within the Adelaide region (line item 11.12 Entitled diversion of allocated surface water to urban water system) made up the majority of the water sourced for urban supply; 42% and 35% respectively. Desalinated water (line item 11.6 Delivery of desalinated water to urban water system) made up the remaining 23% of inflows to the urban water supply system in the Adelaide region.
Potable water consumption within the region (line item 19.4 Delivery to urban water system users) was 137,028 ML during the 2012–13 year, representing 86% of all outflows from the urban water supply system. Smaller volumes of potable water were discharged to South Para Reservoir (line item 19.5 Discharge from urban water system to surface water: 2% of outflows) and transferred out of the region via normal operations in SA Water's service area (line item 19.11 Transfer of water outside region: 3% of outflows). Leakage from the water mains (line item 19.3 urban water system leakage to groundwater: 10%) made up the remaining urban water supply system outflows.
The following figure shows all the inflows and outflows for the urban water supply system. For more detail on a particular flow associated with the urban water supply system, refer to the line item notes. A misbalance of 2,140 ML or 1.3% was calculated for the urban water supply system. This misbalance may be due to a number of factors such as metering inaccuracies, unaccounted losses and inaccuracies in the estimation of certain volumes.
Schematic diagram of water inflows and outflows for Adelaide's urban water supply system during the 2012–13 year; line item numbers are provided in brackets
Customer service information system (CSIS) databases.
Geographic information system (GIS) analysis was used to extract the service point numbers (SPNs) of meters that are located outside the Adelaide region, but are supplied with water from WTPs within the Adelaide region. The SPNs were then used to extract water meter readings for the 2012–13 year for each meter from the CSIS database.
Water consumption was calculated by analysing the difference between consecutive meter readings and summed for 2012–13. To account for meter readings that occurred immediately before or after 2012–13, metered consumption was apportioned based on the following equation:
Vr = ( tr / tm ) × Vm
Vr = volume for metered period within 2012–13 (ML)
tm = length of period between meter readings (days)
tr = length of metered period within 2012–13 (days)
Vm = volume for metered period (ML).
Assumptions, limitations, caveats and approximations