# Evaluating CHIRPS and ERA5 for Long-Term Runoff Modelling with SWAT in Alpine Headwaters
## 2 Materials and Methods
### Evaluation Methods  
In the three catchments (b1 Sill, b2 Drava, b3 Isel), precipitation observations were available at 15, 12 and 13 gauging stations, respectively. The number of ERA5 grid points in \begin{table}
\begin{tabular}{c c c} \hline \hline
**Data Type** & **Data Source** & **Resolution/No. Stations** \\ \hline \multirow{4}{*}{Digital elevation model (DEM)} & **Land** & \\  & \multicolumn{2}{c}{Copernicus—EU DEMV 1.1.1 [07]; [[https://land.opennicus.eu/land.opennicus.eu/land.open-v1.1](https://land.opennicus.eu/land.opennicus.eu/land.open-v1.1)]([https://land.opennicus.eu/land.opennicus.eu/land.open-v1.1](https://land.opennicus.eu/land.opennicus.eu/land.open-v1.1))} & 25 m \(\times\) 25 m \\  & \multicolumn{2}{c}{(accessed on 10 September 2018)} & \\  & EEA-European Soil Data Centre (ESDA) [108] & 1 km \(\times\) 1 km \\  & \multicolumn{2}{c}{[[https://esdaic.ice.eu/ourganet/](https://esdaic.ice.eu/ourganet/)]([https://esdaic.ice.eu/ourganet/](https://esdaic.ice.eu/ourganet/)) (accessed on 11 September 2018)} & 100 m \(\times\) 100 m \\ \multirow{2}{*}{Land use} & \multicolumn{2}{c}{(accessed on 11 September 2018)} & \\  & \multicolumn{2}{c}{(accessed on 11 September 2018)} & \\  & \multicolumn{2}{c}{(accessed on 11 September 2018)} & \\ \hline \multirow{4}{*}{Air temperature, precipitation, snow depth} & **Weather and discharge observations** & \\  & \multicolumn{2}{c}{European Climate Assessment \& Dataset (ECA\&D) [101] \\  & \multicolumn{2}{c}{Data available at [[https://www.ecad.eu/](https://www.ecad.eu/)]([https://www.ecad.eu/](https://www.ecad.eu/)) (accessed on 20 March 2019)} & \\  & \multicolumn{2}{c}{Bundesministerium fur Nachhaltigkeit und} & \\  & \multicolumn{2}{c}{Tourismus—eHYD [110]} & 29 stations \\ \multirow{4}{*}{Presipitation} & \multicolumn{2}{c}{[[https://phy.deyat.yat/](https://phy.deyat.yat/)]([https://phy.deyat.yat/](https://phy.deyat.yat/)) (accessed on 18 March 2019)} & \\  & \multicolumn{2}{c}{Autonome Provving Boene, [[http://weather.proving.bz.it](http://weather.proving.bz.it)]([http://weather.proving.bz.it](http://weather.proving.bz.it))} & \\  & \multicolumn{2}{c}{Bundesministerium fur Nachhaltigkeit und} & \\ \multirow{4}{*}{Discharge} & \multicolumn{2}{c}{Tourismus--eHYD [110]} & 9 stations \\  & \multicolumn{2}{c}{[[https://ehy.deyat/](https://ehy.deyat/)]([https://ehy.deyat/](https://ehy.deyat/)) (accessed on 18 March 2019)} & \\ \hline \multirow{4}{*}{Temperature, wind speed, solar radiation, humidity (CFSR)} & **Climate products** & \\  & \multicolumn{2}{c}{National Centers for Environmental Prediction (NCEP) [52;62;63]} & \\  & \multicolumn{2}{c}{[[https://www.oweight.peah.ca/](https://www.oweight.peah.ca/)]([https://www.oweight.peah.ca/](https://www.oweight.peah.ca/)) (accessed on 25 April 2021)} & 0.5\({}^{\circ}\) \(\times\) 0.5\({}^{\circ}\) \\ \multirow{4}{*}{Precipitation CHIRPS-V2.0} & \multicolumn{2}{c}{Climate Hazards Group InfraRed Precipitation with Station [38],} & \\  & \multicolumn{2}{c}{[[http://firp.chg.ucsb.edu/pub/ops/chg/products/CHIRPS-2.0](http://firp.chg.ucsb.edu/pub/ops/chg/products/CHIRPS-2.0)]([http://firp.chg.ucsb.edu/pub/ops/chg/products/CHIRPS-2.0](http://firp.chg.ucsb.edu/pub/ops/chg/products/CHIRPS-2.0))} & 0.05\({}^{\circ}\) \(\times\) 0.05\({}^{\circ}\) \\ \multirow{4}{*}{Precipitation ERA5} & \multicolumn{2}{c}{(accessed on 25 April 2021)} & \\  & \multicolumn{2}{c}{Grid–European Centre for Medium-Range Weather} & \\  & \multicolumn{2}{c}{Forecastes—ERAS [50;105;106], [[https://cds.climate.coppernicus.eu/](https://cds.climate.coppernicus.eu/)]([https://cds.climate.coppernicus.eu/](https://cds.climate.coppernicus.eu/))} & 0.25\({}^{\circ}\) \(\times\) 0.25\({}^{\circ}\) \\ \multirow{4}{*}{} & \multicolumn{2}{c}{cdsapet/dataset/ reanalysis-era5-single-levels-fab-form} & \\  & \multicolumn{2}{c}{(accessed on 25 April 2021)} & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Spatial, weather and discharge datasets used in this study. the catchments (4, 6, 9) is significantly lower than the number of CHIRPS points (39, 33, 52).