Initial assessment of recharge areas for large karst springs: a case study from the central Zagros Mountains, Iran
- Shahid Chamran University (Iran, Islamic Republic of)
- McMaster University (Canada)
- Ilam University (Iran, Islamic Republic of)
Sousan Spring emerges from the Keyno Anticline, Zagros Mountains (Iran), and the mean annual discharge is ~24 m{sup 3}/s. Geological and hydrochemical evaluations suggest that the spring recharge is from the limestone Ilam-Sarvak Formation (Cretaceous) but the Mafaroon Fault, a major thrust feature, influences the regional groundwater flow path by juxtaposing other strata. Geological, geochemical, stable isotope and water balance studies were employed to interpret this behavior. Using the isotope data, the sources and elevations of the recharge area were found. Temporal variations of the isotopic data were compared with variations of electrical conductivity (EC). Unexpectedly, high EC was associated with a relative increase of discharge and depletion of δ{sup 18}O. Several hypotheses were investigated and approximate water balance studies employed for validation. It was found that an elongated catchment on the Keyno Anticline plus a lesser catchment on a pair of parallel anticlines recharge the aquifer. While the long groundwater flow path along the Keyno Anticline plus guidance by Mafaroon Fault and the adjacent Garou shaly strata lead to increased EC in the Sousan Spring at the end of the dry season, a flow pulse from two adjoining anticlines (Mahalbakh and Shirgoon) arrives at the same time to increase the discharge and deplete the δ{sup 18}O signal. Apparently the spring did not experience true base flow conditions during the recorded hydrological year. Although the spring response to specific precipitation events was similar to typical karst aquifers, standard interpretation of recession curves and related coefficients will not be practical at Sousan.
- OSTI ID:
- 22780888
- Journal Information:
- Hydrogeology Journal, Vol. 26, Issue 1; Other Information: Copyright (c) 2018 Springer-Verlag GmbH Germany, part of Springer Nature; Country of input: International Atomic Energy Agency (IAEA); ISSN 1431-2174
- Country of Publication:
- United States
- Language:
- English
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