ISIMIP2b WaterGAP2: replacement of qr [Updated]

Posted by Matthias Büchner on Nov. 26, 2019

Groundwater recharge (qr) has been retraced and will be replaced by the modeler. Please see the full explanation below and check back for updates on the availability of updated data.

I had to replace groundwater recharge (qr) for WaterGAP2 global water sector and all ISIMIP2b experiments. In the WaterGAP 2.2c model version used in ISIMIP2b, qr was reported as sum of two parts, a) the diffuse groundwater recharge that occurs on land area and b) groundwater recharge below surface water bodies in semi-arid/arid grid cells. However, we found out that the b) part can lead to very high recharge values for large surface water bodies (as the water balance is
calculated in the outflow cell), and especially in inland sinks that contain large lakes. As a consequence, absolute differences of long-term annual qr can reach very high values of (> 10^3) mm/yr for few grid cells which is hard to interpret, especially with other models that might neglect this process. As we do not have a quick fix for this, we decided to report only a) as qr.

[Update 2019-11-27]: new data has been processed and published