South East Queensland
17.4 Leakage to landscape

Supporting Information

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.

Table of storage and transmission loss volume
Water resource plan (WRP) area Water supply scheme (WSS) Storage name Resource operation plan (ROP) Storage Loss
(ML)
Adjusted storage loss
(ML)
ROP transmission loss
(ML)
Total
(ML)
Gold Coast Nerang Advancetown Lake (Hinze Dam)  –
Little Nerang Dam
Total Gold Coast WRP area
Logan Basin Logan River Bromelton Off-Stream Storage 483             483 5,896 8,067
Cedar Grove Weir 110             110
Lake Maroon 1,578           1,578
None Tingalpa Reservoir (Leslie Harrison Dam)
Wyaralong Dam
Total Logan Basin WRP area 2,171             483 5,896 8,067
Moreton Central Brisbane River and Stanley River Mount Crosby Weir
Lake Wivenhoe 174,825       174,825 174,825
Lake Somerset 73,886         73,886 73,886
Central Lockyer Lake Clarendon
Lake Dyer (Bill Gunn Dam)
Cressbrook Creek Lake Cressbrook  –
Lake Perseverance
Lower Lockyer Valley Lake Atkinson (Atkinson Dam)
Pine Valleys Lake Samsonvale (North Pine Dam)  –
Warrill Valley Lake Moogerah
None Enoggera Reservoir
Gold Creek Reservoir
Lake Kurwongbah (Sideling Creek Dam)
Lake Manchester (Cabbage Tree Creek Dam)
Splityard Creek Dam
Total Moreton WRP area 248,711     248,711 248,711
Total SEQ region 250,882     249,194 5,896 256,778
Notes:
  1. Where data were not available within the ROP this has been indicated with (–)
  2. As precipitation was greater than evaporation on all storages during the 2010–11 year, ROP storage losses were not adjusted down to account for evaporative loss.

Quantification Approach

Data Source

Queensland Department of Environment and Resource Management (DERM), storage loss factors from Moreton and Logan Basin ROPs, Water Management System database and DERM staff calculations. Seqwater monthly storage height or volume data.

Provided by

DERM and Bureau of Meteorology.

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.

ROP storage loss factors include a component for net evaporative losses from the storages. Evaporation from storages was included in line item 17.1 Evaporation from surface water, and precipitation on storages was included in line item 9.1 Precipitation on surface water. To prevent double counting of the net evaporative loss from storages, the net evaporative loss calculated by the Bureau of Meteorology was subtracted from the storage loss volumes provided by DERM. Where the net evaporation for an individual storage was calculated to be greater than the ROP storage loss, a storage loss was not recognised for the individual storage. Where precipitation was greater than evaporation, no net evaporation was calculated and the total storage loss was considered in this line item.

Assumptions, Limitations, Caveats and Approximations

As precipitation was greater than evaporation on all storages during the 2010–11 year, ROP storage losses were not adjusted down to account for net evaporative loss. This has resulted in all storage loss from the ROP considered as leakage to landscape. This may have resulted in an overestimate of the leakage to landscape.

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 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. DERM reliability and accuracy rating is B4.

Comparative year

This line item corresponds to line item 14.3 Leakage from connected surface water store reported in the 2010 Account.