Adelaide
Water overview

Significant water events

The Western Mount Lofty Ranges Prescribed Water Resources Area (PWRA) Water Allocation Plan was adopted on 17 September 2013 under the Natural Resources Management Act 2004. The water allocation plan issues water licences to users throughout the region, including SA Water, and includes a number of environmental provisions.

 

Soil moisture

Figure W1 shows that soil moisture was generally average to above average in the Adelaide region during the 2013–14 year (compared against the 1970–2014 period). The soil moisture is based on a conceptual representation of soil water storage and transfer processes averaged over a 5 km x 5 km grid cell derived from the Australian Water Resources Assessment system landscape model (AWRA-L) version 3.0. The model produces a soil moisture grid for the region at a daily time step, which is then averaged over the entire year to produce an annual soil moisture grid. The annual grid represents the mean daily volume of soil moisture across the region during the year.

 

Figure W1 Map of annual soil moisture deciles for the Adelaide region during the 2013–14 year
Figure W1 Annual soil moisture deciles for the Adelaide region during the 2013–14 year

 

Soil moisture levels were depleted in the Adelaide region after the below average rainfall of the 2012–13 year.  Soil moisture conditions improved in the Adelaide region in most areas due to above average rainfall experienced earlier in the 2013–14 year; however, the effect of the drier conditions in the previous year is demonstrated in the below average streamflow in the North Para and Onkaparinga River (see Streamflow). Groundwater flows were also typically lower in 2013–14 when compared to the previous year (see Groundwater in the 'Supporting information' note), as rainfall would have replenished soil moisture before producing runoff into rivers, or contributing to recharge/discharge volumes. 

 

Streamflow

During the 2013–14 year, total annual streamflow in the Adelaide region was below to well below the mean annual flow for two rivers: North Para and Onkaparinga as shown in Table W1.

 

Table W1  Mean annual river flow in the Adelaide region during the 2013–14 year
RiverStreamflow gaugePeriod of recordMean annual flow (ML)2013–14 flow (ML)2013–14 flow as % of mean annual flow
MypongaA50205021978–20147,9269,301117%
North ParaA50505021955–201414,26911,82283%
OnkaparingaA50305041973–201471,78048,27867%


Monthly streamflow for the Myponga, North Para and Onkaparinga rivers is presented in figures W3–W5. Figure W2 shows the location of the streamflow gauges used to prepare these hydrographs.
 

Figure W2 Key gauging stations along the main rivers within the Adelaide region
Figure W2 Key gauging stations along the main rivers within the Adelaide region

 
 
 
Figure W3 Monthly flow for the Myponga River in the 2013–14 year compared to the long-term values for the region
Figure W3 Monthly flow for the Myponga River in the 2013–14 year compared to the long-term values for the region
 
 
 
Figure W4 Monthly flow for the North Para River in the 2013–14 year compared to the long-term values for the region
Figure W4 Monthly flow for the North Para River in the 2013–14 year compared to the long-term values for the region
 
 
 
Figure W5 Monthly flow for the Onkaparinga River in the 2013–14 year compared to the long-term values for the region
Figure W5 Monthly flow for the Onkaparinga River in the 2013–14 year compared to the long-term values for the region
 
 

Overall, for the 2013–14 year, the Myponga River recorded above average annual streamflow; however, Figure W3 shows that flow was variable throughout the year. July and August were the only months that exceeded the long-term average monthly flow, with August 2013 trending toward the 90th percentile. This corresponded with the above average rainfall observed in the Adelaide region (see Climate overview).  Flow throughout the summer months (December–February) was low, with all three months exhibiting lower than average flows.

The North Para River (Figure W4) recorded slightly below average flows for the 2013–14 year. Similar to the other major rivers in the region and consistent with typical winter/summer patterns, flow was higher in July, August 2013 and June 2014 than the drier months. Flows in the North Para were well below average in the months of October–January; however, rainfall in the catchment in February contributed to flow that exceeded the 90th percentile for that month. 

The Onkaparinga River was below average for the 2013–14 year despite the above average rainfall experienced in the area. Like the Myponga River, flows in July-August were higher than average at the start of the reporting period (Figure W5); however, this changed in September where flow was almost half of the mean monthly flow. This drying trend continued throughout the rest of the reporting period, with October observing flows that were close to the 10th percentile and the months of November to May (except February) fell below the 10th percentile. Flow conditions only improved in June 2014 when flows just exceeded the monthly average.   

 

Major water initiatives

The major water initiatives ongoing or completed in the 2013–14 year are presented in Table W2.

 

Table W2  Major water initatives ongoing or completed in the Adelaide region in the 2013–14 year

Initiative

Completion date/Implementation

Description

Lead agency

North South Interconnection System project

Completed 2013–14

Enhances security and flexibility of water supply by connecting Adelaide's southern and northern water supply systems, thereby increasing the distribution network transfer capability.

SA Water

Stormwater reuse

1.       Barker Inlet: stormwater re-use scheme

2.       Adelaide Airport: stormwater scheme

2014–15

Providing alternative water sources by harvesting and treating stormwater for reuse by the Adelaide airport, industrial, commercial and irrigation customers .

SA Water

Central Adelaide water allocation planOngoingOngoing development of combined water allocation plan for Central Adelaide Prescribed Wells Area and Northern Adelaide Plains Prescribed Wells Area.Adelaide and Mount Lofty Ranges Natural Resources Management Board and South Australian Department of Environment, Water and Natural Resources
Unbundling water rightsOngoingProgressive separation of water rights pursuant to Action 61 of the Water for Good plan, so they can be managed as four separate items. Refer to the Department of Environment, Water and Natural Resources website for further information.South Australian Department of Environment, Water and Natural Resources and Adelaide and Mt Lofty Ranges Natural Resources Management Board