In WaterGAP2, an inconsistent handling of total actual water consumption (atotuse) has been detected, which leads to negative values of water consumption. For a more detailed description please see Caveat_WaterGAP2_atotuse.pdfCaveat_WaterGAP2_atotuse.pdf.
The model owners recommend setting these negative values to zero. The problem will be solved in WaterGAP version 2.2d which will be used in ISIMIP3. Simulations in ISIMIP2 will not be re-run.