Ord
41.3 Runoff into storages

Supporting Information

Runoff into all storages was not explicitly calculated for the 2010–11 year. However, runoff into the Ord River upstream of Lake Argyle (20,908,921 ML) was calculated. Thus runoff is used as an estimate of the runoff into Lake Argyle. This runoff is further used to estimate the runoff into storages. 

This is expected to be an underestimate of the true runoff to storages because none of the runoff to Arthur Creek Dam, Moochalabra Dam or Lake Kununurra are explictly calculated. Nevertheless, providing the magnitude of the runoff reported here is deemed to be useful to users of the account.

Runoff to river reaches in Ord region
River reach Volume 201011 (ML) Volume 200910 (ML)
Keep River      5,971,977    1,671,281
Ord River downstream of  Lake Argyle    10,259,733    1,623,419
Ord River upstream of Lake Argyle    20,908,921    2,131,562
Total    37,140,631    5,426,262

 

Quantification Approach

Data Source

Department of Water: Water Information (WIN) database.

Provided by

Department of Water.

Method

Runoff was calculated based on a water balance approach using measured data. Inflow is calculated using the following water balance equation:

Inflow = ΔS + O + E - Pb - T

Where:

ΔS is the change in storage
O is total outflow
E is evaporation
Pb is the volume of water pumped backed in
T is the volume of water transferred in.

Total outflow (O) is calculated using the following equation:

O = Sp + Sc + D + R

Where:

Sp is spillage
Sc is scour
D is volume of water abstracted
R is volume of riparian releases.

 

Assumptions, Limitations, Caveats and Approximations

Runoff assumes that all inflows and outflows are adequately quantified.

Uncertainty Information

Runoff is derived from measured and modelled data. The uncertainty estimate was not quantified.