USING HYDROGEOCHEMICAL AND ECOHYDROLOGIC RESPONSES TO UNDERSTAND EPIKARST PROCESS IN SEMI-ARID SYSTEMS, EDWARDS PLATEAU, TEXAS, USA/UPORABA HIDROGEOKEMICNIH IN EKOHIDROLOSKIH ODZIVOV ZA RAZUMEVANJE EPIKRASKIH PROCESOV V POLSUSNIH SISTEMIH, PLANOTA EDWARDS, TEKSAS, ZDA

• Published in: Acta carsologica Vol. 42; no. 2/3; p. 315
• Main Authors: Schwartz, Benjamin F, Schwinning, Susanne, Gerard, Brett, Kukowski, Kelly R, Stinson, Chasity L, Dammeyer, Heather C
• Format: Journal Article
• Language: English; Slovenian
• Published: Ljubljana Scientific Research Center of the Slovenian Academy of Sciences and Art 01.05.2013
• Subjects: USA, Texas, Edwards Plateau; USA, Texas
• ISSN: 0583-6050; 1580-2612

The epikarst is a permeable boundary between surface and subsurface environments and can be conceptualized as the vadose critical zone of epigenic karst systems which have not developed under insoluble cover. From a hydrologic perspective, this boundary is often thought of as being permeable in one direction only (down), but connectivity between the flow paths of water through the epikarst and the root systems of woody plants means that water moves both up and down across the epikarst. However, the dynamics of these flows are complex and highly dependent on variability in the spatial structure of the epikarst, vegetation characteristics, as well as temporal variability in precipitation and evaporative demand. Thresholds are strongly correlated with antecedent potential evapotranspiration and rainfall, suggesting control by the moisture status of the epikarst evapotranspiration zone. The epikarst and unsaturated zone in this region can be conceptualized as a variably saturated system with storage in fractures, matrix porosity, and in shallow perched aquifers, most of which is inaccessible to the root systems of trees, although woody vegetation may control recharge thresholds.