South East Queensland
17.4 Surface water leakage to landscape
Supporting information
The volumetric value for the line item at the end of the 2012–13 year was 259,661 ML.
This line item represents the losses from storages and rivers in the South East Queensland (SEQ) region. The following table contains the resource operation plan (ROP) storage loss values and the adjusted storage loss calculated by removing net evaporation. This line item consists of the adjusted storage loss volume.
Leakage from storages was estimated for specific storages and rivers only as data were not available for all storages and rivers.
| Water resource plan (WRP) area | Water supply scheme (WSS) |
Storage name |
Resource operations plan (ROP) storage loss |
Adjusted storage loss |
ROP transmission loss |
Total |
(ML) |
(ML) |
(ML) |
(ML) |
|||
| Gold Coast | Nerang | Hinze | – |
– |
– |
– |
| Little Nerang |
||||||
| Total Gold Coast WRP area | – |
– |
– |
– |
||
| Logan Basin | Logan River | Bromelton Off-Stream Storage | 482 |
482 |
4,132 |
6,209 |
| Cedar Grove Weir | – |
– |
||||
| Lake Maroon | 1,595 |
1,595 |
||||
| none | Leslie Harrison |
– |
– |
– |
– |
|
| Wyaralong | – |
– |
– |
– |
||
| Total Logan Basin WRP area | 2,077 |
2,077 |
4,132 |
6,209 |
||
| Moreton | Central Brisbane River and Stanley River | Mount Crosby Weir | – |
– |
– |
– |
| Wivenhoe | 179,356 |
179,356 |
179,356 |
|||
| Somerset | 74,096 |
74,096 |
74,096 |
|||
| Central Lockyer | Clarendon | – |
– |
– |
– |
|
| Bill Gunn | ||||||
| Cressbrook Creek | Cressbrook Creek |
– |
– |
– |
– |
|
| Perseverance | ||||||
| Lower Lockyer Valley | Atkinson |
– |
– |
– |
– |
|
| Pine Valleys | North Pine | – |
– |
– |
– |
|
| Warrill Valley | Moogerah | – |
– |
– |
– |
|
| none | Enoggera |
– |
– |
– |
– |
|
| Gold Creek |
||||||
| Lake Kurwongbah |
||||||
| Lake Manchester |
||||||
| Splityard Creek |
||||||
| Total Moreton WRP area | 253,452 |
253,452 |
0 |
253,452 |
||
| Total SEQ region | 255,529 |
255,529 |
4,132 |
259,661 |
||
Table Note:
1. Where data were not available within the ROP this has been indicated with (–)
2. Department of Natural Resources and Mines (DNRM) has a factor in the ROP to calculate losses at cedar grove Weir but there was no data available at the time of reporting.
3. No adjustment was made to calculation
Quantification approach
Data source
Department of Natural Resources and Mines (DNRM): storage loss factors from Moreton and Logan Basin ROPs, Water Management System (WMS) database, and DNRM staff calculations; Seqwater monthly storage height and/or volume data; Bureau of Meteorology (the Bureau): precipitation on and evaporation from surface water storages
Provided by
DNRM; Seqwater; the Bureau.
Method
Storage loss is the loss in the water supply scheme (WSS) storages. Where storage loss was not specifically evaluated as part of ROP reporting requirements, the storage loss allowance detailed in the ROPs was used as an estimate. This was done by adding the storage loss allowances calculated for each month, based on the storage surface area at the start of month and the application of the difference between monthly storage loss factors in the applicable ROP tables. The Moreton and Logan Basin ROPs provide storage loss tables for Lake Wivenhoe, Lake Somerset and Lake Maroon, Cedar Grove Weir and Bromelton Off–Stream Storage.
The value for each storage was calculated as follows:
- For a storage, net evaporation loss was calculated by subtracting precipitation (line item 9.1 Precipitation on surface water) from the evaporation (line item 17.1 Evaporation from surface water). If the calculation resulted in a negative value, the net evaporation loss was considered as zero.
- This net evaporation loss was subtracted from ROP loss (provided by DNRM) to calculate the adjusted storage loss for the line item. This is to prevent double counting because ROP loss includes net evaporative loss as estimated by DNRM. If the resulting value was less than zero, no value was considered for the storage.
Assumptions, limitations, caveats and approximations
The volumes are from application of the ROP calculation and therefore include evaporation losses. No adjustment was made to the calculation.
It has been assumed that the WMS database data were current, accurate and correct.
The Moreton and Logan Basin ROPs list loss factors to apply when estimating losses from storages where the storages are part of the WSS. Where the storages are not part of a WSS, losses were not available and could not be quantified accurately.
Losses from the storages that form part of a WSS have been estimated and reported where information was available to allow accurate quantification. Therefore:
- transmission losses were not reported in the Moreton or Gold Coast water resource plan (WRP) areas
- storage losses were not reported in the Gold Coast WRP area.
Uncertainty information
Derived from storage loss estimates. DNRM reliability and accuracy rating is B4 (Department of Environment and Resource Management 2011).