QWAST uses a discharge distribution table to distribute the discharge from Lobith to the Waal, Nederrijn and IJssel. The table includes which proportion of the discharge from Lobith goes to the Pannderdensch Kanaal, and a table about which percentage of the discharge of the Pannderdensch Kanaal goes to the Nederrijn. The percentages are given for each Lobith discharge, for example:
| Discharge at Lobith (m3/s) | Percentage to Pannerdensch Kanaal from Lobith (fraction) | Percentage to Nederrijn from Pannerdensch Kanaal (fraction) | Discharge Pannerdensch Kanaal (m3/s) | Discharge Waal (m3/s) | Discharge Nederrijn (m3/s) | Discharge IJssel (m3/s) |
| 0 | 0.18 | 0.19 | 0 | 0 | 0 | 0 |
| 600 | 0.18 | 0.19 | 105 | 495 | 20 | 85 |
| 650 | 0.18 | 0.17 | 115 | 535 | 20 | 95 |
| 700 | 0.18 | 0.16 | 125 | 575 | 20 | 105 |
| 750 | 0.18 | 0.15 | 134 | 615 | 20 | 114 |
| 800 | 0.18 | 0.14 | 144 | 655 | 20 | 124 |
| 823 | 0.18 | 0.13 | 149 | 674 | 20 | 129 |
The light blue colums are the input for QWAST, and the white colums are the resulting discharges calculated by QWAST. This calculation is valid if there is no discharge through the "Betuwe Inlaat" (Gemaal Pannerling to the Linge). If there is a discharge for Betuwe Inlaat, the discharge of the Pannerdensch Kanaal is decreased with that value, and only the rest of the water is distributed to the Nederrijn and IJssel:
| Discharge at Lobith (m3/s) | Percentage to Pannerdensch Kanaal from Lobith (fraction) | Percentage to Nederrijn from Pannerdensch Kanaal (fraction) | Discharge Pannerdensch Kanaal (m3/s) | Discharge Waal (m3/s) | Discharge Betuwe Inlaat | Discharge Nederrijn (m3/s) | Discharge IJssel (m3/s) |
| 0 | 0.18 | 0.19 | 0 | 0 | 0 | 0 | 0 |
| 600 | 0.18 | 0.19 | 105 | 495 | 10 | 18 | 77 |
| 650 | 0.18 | 0.17 | 115 | 535 | 10 | 18 | 87 |
| 700 | 0.18 | 0.16 | 125 | 575 | 10 | 18 | 96 |
| 750 | 0.18 | 0.15 | 134 | 615 | 10 | 19 | 106 |
| 800 | 0.18 | 0.14 | 144 | 655 | 10 | 19 | 116 |
| 823 | 0.18 | 0.13 | 149 | 674 | 10 | 19 | 121 |
This data is stored in QWAST in the CoefficientSetFiles: ...\QWAST\Config\CoefficientSetsFiles\VerdeelsleutelRijn_bodem2050.xml. There are several coefficient set files with different extension "bodem2018", "bodem2050" etc. The user can decide which coefficient file to use, reflecting the Dutch geography and the related water distribution between the Rijn branches. There are two ways to give this information to QWAST:
- If QWAST is run from the Forecast Tree or from through the Manual Workflows, the property is read from the global.properties file.
- If QWAST is run from a batch file this properity can be overwritten in the batch file.
If there is new information available how the water between the Rijn branches should be distributed, the user can create a new file "VerdeelsleuterRijn_XXX" and can call it from the global properties or from a batch file.
More on discharge distribution can be found Discharege Nederrijn / Driel.
