Water isotopes of lysimeters and precipitation in 53 forest plots across Switzerland

We present stable isotope measurements (d18O and dD) of 3698 soil lysimeter waters from 53 forest plots in Switzerland collected between 2019 and 2022. We interpolated stable isotopes of precipitation (d18O and dD) for the 53 forest plots from isotope data collected by the Swiss Federal Office for the Environment (FOEN) National Groundwater Monitoring (NAQUA) ISOT module. Precipitation isotope data was interpolated for forest plot locations following the method in (Allen et al., 2018). Additionally, we include Matlab codes that will fit sinusoidal functions to data from each site for precipitation, and each site and soil depth for lysimeters. Lastly, there is a spreadsheet showing the calculations of young water fractions from the sinusoidal function amplitudes.