Dataset includes isotopic values of soil water and groundwater samples collected from an experimental plot located at the Kenttärova hilltop, within the Pallas catchment. The locations of sampling profiles within the plot are displayed in EP_sketch.pdf image. The samples were collected between June 2019 and September 2020. The experimental plot was irrigated with 163.6 mm of deuterated water (mean weighted 2H value of 79.38 ± 5.3 ‰) during a 30-hour period in late August 2019 (Aug 27 16:00 h – Aug 29 22:00 h). Suction lysimeter soil water samples were obtained, if any water was available, from 2 profiles (S2 and S3) and three depths (5, 30 and 60 cm) by applying 600 kPa of suction. The samples were collected biweekly during 2019 and 2020 summer seasons, every 2 days during the 2020 snowmelt and hourly during the 30-hour irrigation period. Soil water samples from pan lysimeters, located at 35 cm depth in profiles S2 and S3, were collected concurrently with suction lysimeter soil water samples. Hand-held vacuum pump was used to extract the samples from 1 L sample collecting bottles. Groundwater samples were obtained from a 1.3 m deep groundwater well, located in profile S2. Groundwater was only sampled during the 30-hour irrigation period. Samples from surface water accumulated in ponds were collected opportunistically during the 30-hour irrigation period. Bulk soil water isotopic signal was obtained from the soil cores that were collected 4 times during the irrigation period, and 3 more times afterwards (September 2019, April 2020 and June 2020). Two replicate cores were collected each time, and all cores were sampled at 5 cm increments down to a 50 cm soil depth and at 10 cm increments from a 50–100 cm depth. Direct equilibration method was used to measure the isotopic composition of bulk soil water, using a cavity ring-down spectroscopy analyzer (Picarro L2140-i model, Picarro Inc., Santa Clara, CA, USA). The isotopic composition of liquid soil water samples (from groundwater, suction and pan lysimeters) was analyzed on the same Picarro device. Detailed description of isotopic analyses can be found in https://onlinelibrary.wiley.com/doi/10.1002/hyp.14811 (Laboratory analysis section).

2023