Spring response to precipitation events using δ¹⁸O and δ²H in the Tanour catchment, NW Jordan

ABSTRACT

The Tanour spring is one of the several karst springs located in the northern part of Jordan. Water samples from the Tanour spring and precipitation were collected in the area of Ajloun in NW Jordan for the analysis of stable oxygen and hydrogen isotopes to evaluate the spring response to precipitation events. Rainwater and snow samples were collected from different elevations during winters of 2013–2014 and 2014–2015. In addition, spring samples were collected between December 2014 and March 2015. δ¹⁸O values in rainwater vary from −3.26 to −17.34 ‰ (average: −7.84 ± 3.23 ‰), while δ²H values range between −4.4 and −110.4 ‰ (average: −35.7 ± 25.0 ‰). Deuterium excess ranges from 17.8 to 34.1 ‰ (average: 27.1 ± 4.0 ‰). The Local Meteoric Water Line for the study area was calculated to be δ²H = 7.66*δ¹⁸O + 24.43 (R² = 0.98). Pre-event spring discharge showed variation in δ¹⁸O (range −6.29 to −7.17 ‰; average −6.58 ± 0.19 ‰) and δ²H values (range −28.8 to −32.7 ‰; average: −30.5 ± 1.0 ‰). In contrast, δ¹⁸O and δ²H rapidly changed to more negative values during rainfall and snowmelt events and persisted for several days before returning to background values. Spring water temperature, spring discharge, and turbidity followed the trend in isotopic composition during and after the precipitation events. The rapid change in the isotopic composition, spring discharge, water temperature, and turbidity in response to recharge events is related to fast water travel times and low storage capacity in the conduit system of the karst aquifer. Based on the changes in the isotopic composition of spring water after the precipitation events, the water travel time in the aquifer is in the order of 5–11 days.

KEYWORDS:

• deuterium excess
• hydrogen-2
• Jordan
• karst system
• meteoric water line
• oxygen-18
• precipitation
• water travel time

Acknowledgements

The authors would like to express their gratitude to Prof. Dr-Ing. Thomas Ptak for his precious advice. Also we would like to thank Eng. Ali Subah from the Ministry of Water and Irrigation (MWI) and the Federal Institute for Geosciences and Natural Resources (BGR) for the telemetry data provided for Tanour spring water temperature, discharge, and turbidity, and support during the field trips. In addition, we are grateful to Eng. Kifah Mrayan from the Water Authority of Jordan (WAJ) for logistic support and the personnel of the (WAJ) at Tanour spring for their help in collecting water samples.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was funded by the Federal Ministry of Education and Research (BMBF) via the German Academic Exchange (DAAD) special programme (NaWaM) for the doctoral position of Ibraheem Hamdan.