Stable isotopes of precipitation and spring waters reveal an altitude effect in the Anti-Lebanon Mountains, Syria

Abstract

Stable isotopes (deuterium and oxygen‐18) of precipitation and four springs of the Figeh spring system were studied between March 2011 and July 2012 in the karstic Anti‐Lebanon Mountains in Western Syria. Almost two thirds of the drinking‐water supply of Damascus City, the capital of Syria, is being exploited from the Figeh spring system. About 70 samples were collected from precipitation, and 1000 samples from springs in at least weekly time resolution. Observed mean values for Figeh spring system agree well with published data from earlier studies and are between −8.7‰ and −7.3‰ for δ18O and −50‰ and −40‰ for δ2H. Time series indicate seasonal patterns and short‐term influences, reflecting direct contribution from fast runoff components during snowmelt. Deuterium excess values between 23‰ and 14‰ for the spring samples correspond to precipitation originating from the Mediterranean Sea. Own precipitation collected over one season at two stations leads to altitude effects of −0.14‰/100 m and −1.15‰/100 m for δ18O and δ2H, respectively, which are lower than those reported in earlier work. Mean catchment altitudes were estimated using values for low‐flow periods, which lead to 1800 m a.s.l. for Figeh Main spring, 1500 m a.s.l. for Haroush spring and about 1100 m a.s.l. for the springs Kefar Aloumed and Ein Habeeb. Stable isotope concentrations uniquely characterize springs that are located close together, and estimated recharge catchment altitudes allow a profound risk management. Catchment altitude estimations strongly depend on a proper description of precipitation stable isotope input. Copyright © 2016 John Wiley & Sons, Ltd.

Stable isotope‐based mean catchment altitudes of springs in the Lebanon Mountains

“…Snow isotope composition varied from one year to the other, as it was found in earlier snow isotope surveys in Rocky Mountain catchments (Koeniger et al, ) and in the Black Forrest in Germany (Wenninger, Koeniger, & Schneider, ). However, a pronounced stable isotope altitude effect was visible for spring water, which is related to precipitation and snowmelt effects, in the Lebanon and Anti‐Lebanon Mountain ranges (related BGR investigations were conducted in the Figeh spring catchment; see Koeniger et al, ).…”

“…Siegenthaler and Oeschger () studied altitude effects in the Alpine mountains in Switzerland from monthly precipitation samples of six stations and derived an altitude gradient of −0.26‰ per 100 m for δ 18 O. Gat and Dansgaard () described altitude effects for Israel and Palestine mountains. Wagner and Geyh () reported altitude effects for Syria in the Anti‐Lebanon Mountains of −0.25‰ per 100 m for δ 18 O, and Koeniger, Toll, and Himmelsbach () found altitude effects in the same area of −0.14‰ per 100 m and −1.15‰ per 100 m for δ 18 O and δ 2 H, respectively. For an estimation of recharge areas, it is necessary to determine an isotope altitude effect in precipitation, which affords several precipitation collectors at different altitudes and representative observation times; otherwise, altitude estimations might be biased by large uncertainties (Wagner & Geyh, ).…”

“…The Lebanon and Anti‐Lebanon mountain ranges are mainly fed by precipitation originating from the West, crossing the Mediterranean Sea. The Mediterranean Sea is known as a source for secondary evaporation that characteristically influences precipitation stable isotopic composition and causes high values of deuterium excess ( d values), which was described, for example, by Gat and Carmi (), Gat (), IAEA (, ), and Koeniger et al (). Large springs on the luv (western) and lee (eastern) sides of the Lebanon and Anti‐Lebanon mountain ranges such as Figeh spring in Syria and Jeita spring in Lebanon reflect such high d excess patterns.…”

Differential isotopic characteristics of eco‐hydrologic processes in a subtropical watershed, China

“…Since the development of isotope‐ratio mass spectrometry, global and local patterns in D/H and 18 O/ 16 O variations of precipitation have been extensively investigated (Wen et al, ). Stable isotope values in precipitation generally depend on a host of atmospheric and geographic parameters, such as precipitation amount as well as temperature, latitude, altitude, and distances to the coast (Koeniger, Toll, & Himmelsbach, ; van Geldern, Kuhlemann, Schiebel, Taubald, & Barth, ). These isotopic effects and their spatial variability are associated with moisture sources, rainout history, and atmospheric conditions that lead to precipitation (Dansgaard, ; J. R. Liu et al, ; Zhang, Guan, Zhang, Zhang, & Yao, ).…”

Multiyear Increase in the Stable Isotopic Composition of Stream Water From Groundwater Recharge Due to Extreme Precipitation

“…The understanding of changes in the isotopic composition of surface and shallow groundwater is important for documenting changes in climate and precipitation regime change (Puntsag et al, ). The use of stable isotopes in hydrological studies is becoming a widespread component of hydrologic analysis (Clark & Fritz, ; Dansgaard et al, ; Fricke et al, ; Gat et al, ; Gibson et al, ; Jasechko et al, ; Jouzel et al, ; Koeniger et al, ; Mazor, ; Rozanski, ). The development of distributed isotopic sampling of precipitation and surface water isotopes has led to landscape isotopic characterization—(isoscapes) and the proliferation of large isotope data sets (Bowen & Revenaugh, ; Bowen et al, ).…”