The hydrology of an ephemerally flooded doline: Pwll-y-Felin, South Wales, UK

Farr, Gareth; Naughton, Owen; Sadasivam, Sivachidambaram; Kendall, Rhian; Saville, Jonathan; Bowring, Alan. 2016 The hydrology of an ephemerally flooded doline: Pwll-y-Felin, South Wales, UK. Cave and karst science, 43 (1). 41-47.

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The first annual hydrograph from an ephemerally-flooded doline in the UK is described. Flood duration and volume were characterised by combining water-level data with a detailed topographic survey. Rapid surface runoff of Na–SO4-type water is derived from a localized topographic catchment. The inflow stream produced a ‘flashy’ hydrograph with maximum flood depths reaching 7m when the doline can contain 7,383 m3 of water. Flooding occurred over 161 of the 365 day study period, with an average flood depth of 2.4m. Stage dependent drainage properties suggested that water loss is greater when the flood depth is >3m, indicating that there may be additional drainage conduits at higher levels within the doline. A conservative estimate of 138 ML year is provided for net loss of water to the underlying aquifer. The vegetation shows some zonation potentially related to flood duration, with higher diversity in the marginal zone subject to the greatest fluctuation in water levels. The classification of Pwll-y-Felin and other small ephemeral karstic water bodies should be considered not only as geological landforms but as small karstic dependant wetlands. Under-recording of small, isolated temporary water bodies is of concern to international conservation bodies. The methodology presented can help to characterize the hydrology of ephemerally flooded dolines and could be used better to understand karst dependent habitats, recharge in karst aquifers, water budget calculations and to improve management and regulation in karst aquifers.

Item Type: Publication - Article
Date made live: 29 Apr 2016 12:19 +0 (UTC)

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