Impact model: WaterGAP2

WaterGAP2 is a global water availability and water use model. Some introducing information can be found here: and at For participating in ISIMIP FastTrack we have used WaterGAP 2.2 (described in 10.5194/hess-18-3511-2014). WaterGAP22ISIMIP2a is a model version which is based on WaterGAP 2.2 (described in 10.5194/hess-18-3511-2014) but applied to the specifics of the simulation round ISIMIP2a. WaterGAP22c is a model version (WaterGAP 2.2c, described in 10.5194/hess-20-2877-2016) used for phase ISIMIP2b. Currently, we are re-running ISIMIP2a with WaterGAP22c to allow consistent assesments. For ISIMIP3, we will use WaterGAP22e (WaterGAP 2.2e) which is the successor of WaterGAP 2.2d (described in 10.5194/gmd-14-1037-2021).

Water (global)
Contact Person

Information for the model WaterGAP2 is provided for the simulation rounds shown in the tabs below. Click on the appropriate tab to get the information for the simulation round you are interested in.

Basic information
Model Version: WaterGAP 2.2
Model Homepage:
Model License: CC-BY-NC-4.0
Reference Paper: Main Reference: Portmann F, Döll P, Eisner S, Flörke M et al. Impact of climate change on renewable groundwater resources: assessing the benefits of avoided greenhouse gas emissions using selected CMIP5 climate projections. Environmental Research Letters,8,024023,2013
Reference Paper: Other References:
Person Responsible For Model Simulations In This Simulation Round: Martina Flörke
Output Data
Experiments: historical, rcp26, rcp45, rcp60, rcp85
Climate Drivers: GCM atmospheric climate data (Fast Track)
Date: 2013-12-17
Spatial Aggregation: regular grid
Spatial Resolution: 0.5°x0.5°
Temporal Resolution Of Input Data: Climate Variables: daily
Temporal Resolution Of Input Data: Soil: constant
Input data sets used
Simulated Atmospheric Climate Data Sets Used: GCM atmospheric climate data (Fast Track)
Climate Variables: tas, rlds, rsds, pr
Was A Spin-Up Performed?: Yes
Spin-Up Design: initializing with starting simulations in 1951
Soil Layers: 1 layer with 0.1-4 m depth (depending on land use)
Water Use
Water-Use Types: surface water use, groundwater use
Water-Use Sectors: irrigation, domestic, manufacturing, electricity, livestock
Runoff Routing: Linear reservoir, variable flow velocity based on Manning-Strickler
Routing Data: DDM30
Land Use
Land-Use Change Effects: Only static land use map is used (see "landuse" variant in
Dams & Reservoirs
Dam And Reservoir Implementation: see
Was The Model Calibrated?: True
Which Years Were Used For Calibration?: variable, depending on data availability
Which Dataset Was Used For Calibration?: WFD
How Many Catchments Were Callibrated?: 1312
How Is Vegetation Represented?: A very simplified LAI development model for canopy evaporation is included (see appendix of Müller Schmied et al., 2014, HESS)
Potential Evapotranspiration: Priestley-Taylor with varying alpha factor depending on aridity
Snow Melt: degree day method