Mean Annual discharge data ( 1986-2014 ) for the “ Bowen at Myuna ” catchment ( 12 ) and relevant tributaries are shown , in Table 8 . The catchment has a discharge of ~ 1000 Gigalitres , and the “ Broken River at Mount Sugarloaf ”( 3 ) supplies the majority (~ 70 %) of the observed flow . By comparison , due west of the “ Broken River ” lies the “ Little Bowen ”( 6 ), here rainfall and runoff (~ 90 mm ) are much lower . The “ Bowen River at Jacks Creek ”( 8 ) is shortly downstream from the confluence of the Little Bowen and Broken , and this site contributes ~ 80 % of the Myuna flow (~ 70 % Broken and ~ 10 % Little Bowen ). Despite its relatively large area , western draining “ Rosella Creek ”( 9 ) contributes ~ 10 % of the flow . Glenmore Creek ( 10,11 ) and other minor areas make up the remainder .
Table 8 . Mean annual discharge and runoff ( 1986-2014 ) for each contributing site / sub-catchment within the “ Bowen at Myuna ” catchment .
GBR Source Model
GBR Source Model
Gauged |
|
|
|
|
|
|
|
|
% |
ID |
Sub Basin |
Site / Sub Catchment |
Catchment |
Area ( km2 ) |
Flow ( ML ) |
Flow ( ML ) |
Runoff ( mm ) |
Discharge |
1 Bowen Myuna Broken River |
Broken River at Urannah |
1,118 |
448,133 |
477,432 |
427 |
47 |
2 |
Broken River |
Emu Creek |
199 |
18,021 |
91 |
2 |
3 |
Broken River |
Broken River at SugarLoaf |
2,248 |
677,598 |
301 |
66 |
4 |
Little Bowen |
Exe Creek |
163 |
- |
|
- |
5 |
Little Bowen |
Little Bowen River Exmoor |
1,209 |
115,762 |
96 |
11 |
6 |
Little Bowen |
Little Bowen Junction |
1,462 |
128,094 |
88 |
13 |
7 |
Pelican Creek |
Flagstone Creek |
220 |
21,035 |
96 |
2 |
8 |
Bowen River at Jacks Creek Bowen River at Jacks Creek |
4,250 |
840,155 |
198 |
82 |
9 |
Rosella Creek |
Rosella Creek |
1,425 |
88,631 |
62 |
9 |
10 |
Glenmore |
Parrott and Cockatoo Creek |
569 |
30,512 |
54 |
3 |
11 |
Glenmore |
Ten Mile Creek |
343 |
23,206 |
68 |
2 |
12 Bowen Myuna Bowen Myuna |
Bowen Myuna |
7,074 |
1,002,682 |
1,023,788 |
145 |
100 |
To better , understand constituent transport and assess loads , discharge for the period was classified into events ( Dougall and Carroll 2013 ). These were defined as having a peak daily discharge greater than 20,000 megalitres ( ML ) per day . To determine the duration of the flow event , an event start date began when flow discharges increased to > 5,000 ML / d , and ended when discharge fell below 5000 ML / d . The criteria captured ~ 75 % of the total runoff at the “ Bowen at Myuna ” site with the remaining 25 % labelled as “ Other ”.
The analysis identified 54 events for the 34 year period ( 1986-2020 ). On average most years have 1 or more events , however 8 years have had zero events and these are more likely to be El-Nino years . A statistical standout was the 1998 / 1999 water year that had 6 events .
A calculation of “ likely ” hydrologic catchment sources shows that the Broken River generally dominates events . For example :
• 24 of the 54 events , had ~> 70 % of their water sourced from the Broken River ;
• 10 events are almost exclusively Broken River ;
• Only 5 events have < 30 % of Broken River discharge .
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