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Once an area sketch has been drawn, extract the desired data by right clicking and selecting one of the following options 'Calculate Budget' from the pop-up menu: 'Show Volume Summation', 'Show Area Times Average Level' or 'Show Area Mass Balance'. The corresponding graph will show automatically.. The 'Calculate Budget' option will perform one of the following calculations, depending on the type and the dimension of the selected data (The dimension can be defined in a parameterGroup in the region configuration).
Grids that contain scalar data (e.g. water levels or rainfall data):
- For dimensions L3/T (e.g. flow in m3/s), L3 (e.g. volume in m3) and 'amount of substance' the calculation will be 'volume summation'. This calculates Volume Summation: shows the sum of the values inside the area. This uses all grid cells that are (partially) inside the area. The value of each grid cell is weighted using the fraction of the grid cell that is inside the area.
- Area Times Average Level: shows For dimensions L/T (e.g. velocity in m/s) and L (e.g. water level in m) the calculation will be 'area times average level'. This calculates the average level inside the area multiplied by the size of the area. This uses all grid cells that are (partially) inside the area. The value of each grid cell is weighted using the fraction of the grid cell that is inside the area.
- If the selected data has another dimension, or no dimension is configured for the selected data, then the options 'Start Drawing Area' and 'Calculate Budget' are not available.
Grids that contain horizontal flow data in the form of u,v vectors:
- For dimension L3/T (e.g. flow in m3/s) the calculation will be 'mass balance horizontal flux'. This calculates Area Mass Balance: shows the net horizontal flow into/out of the area. This uses all grid cells that are for at least 50% inside the area.
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- For dimension L/T (e.g. velocity in m/s) the calculation will be 'mass balance horizontal velocity'. This multiplies for each grid cell the value for u, respectively v, with the height of the gridcell, respectively the width of the grid cell, to get flow values (The height of the flowing water mass is taken to be 1). Then the net horizontal flow into/out of the area is calculated. This uses all grid cells that are for at least 50% inside the area.
- If the selected data has another dimension, or no dimension is configured for the selected data, then the options 'Start Drawing Area' and 'Calculate Budget' are not available.
To extract data for a different area just start drawing another area. This will erase the previous sketch. The area sketch can also be erased by right clicking and selecting 'Delete Sketch' from the pop-up menu.
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