The MaRIUS-G2G datasets: Grid-to-Grid model estimates of flow and soil moisture for Great Britain using observed and climate model driving data

The MaRIUS-G2G datasets were produced for the MaRIUS (Managing the Risks, Impacts and Uncertainties of drought and water Scarcity) project, using the Grid-to-Grid (G2G) national-scale hydrological model for Great Britain. There are six separate datasets, with each of three combinations of meteorological driving data (two observation-based and one from climate model ensembles) used to produce two types of outputs (daily time-series of natural river flow for 260 sites, and monthly 1 x 1 km grids of natural flow and soil moisture in the unsaturated zone). The driving data required by G2G are rainfall and potential evaporation (PE). Two of the datasets from observation-based driving data use rainfall from CEH-GEAR (CEH-Gridded Estimates of Areal Rainfall) with PE from MORECS (Met Office Rainfall and Evaporation Calculation System), and cover the period 1960-2015, while the other two use CEH-GEAR rainfall with PE derived from 5 km temperature data using the Oudin method, and cover 1891-2015. The two datasets based on driving data (rainfall and PE) from the climate model ensembles cover three periods: Historical Baseline (1900-2006), Near-Future (2020-2049), and Far-Future (2070-2099). Data for a 30-year Baseline period (1975-2004), against which the Near-Future and Far-Future periods should be compared, are also available directly. There are 100 members in each ensemble, and the future periods use the RCP8.5 emissions scenario. This paper provides details of the G2G model and the different sets of meteorological driving data, as well as the availability and formatting of the output datasets. It also describes some recent and potential applications of the datasets, which have already been used to support historical and future analyses of low flow and drought characteristics across Britain, and provides some guidance on how the climate model-driven datasets should (and should not) be used.