Analysis of well hydrographs in a karst aquifer: Estimates of specific yields and continuum transmissivities

Derivation of effective hydraulic parameters of a Karst Aquifer from discharge hydrograph analysis

“…In order to establish a value for the variable L in a karst terrain, where the boundaries of the drainage divide can change spatially and temporally under different aquifer conditions, detailed tracing experiments are required. This information typically does not exist for most karst aquifers, so it is common practice to assign each discharge location a value of L that is measured from the discharge point to the topographically defined groundwater drainage divide [Shevenell, 1996;Teutsch, 1992]. Equation ( …”

“…This method is based upon a Darcian theory of flow, which may not be valid for higher flow rates through the aquifer. Despite this theoretical limitation this method and other similar hydrograph methods have been successfully applied to several karst systems [Shevenell, 1996;Padilla et al, 1994;Sauter, 1992;MilanoviE, 1981;Atkinson, 1977].…”

Comparative analysis between analytical approximations and numerical solutions describing recession flow in unconfined hillslope aquifers

“…Under strong assumptions, he found that the outflow from an aquifer with a concave floor had the form Ce -αt , with C being an arbitrary value depending on the initial conditions and α (generally known as recession coefficient) a positive constant dependent of the geometric configuration of the aquifer and its hydraulic conductivity. During the years, exponential decay relationships of the same type Q ~ e -αt were derived by Maillet (1905), Horton (1933), Nathan and McMahon (1990), Vogel and Kroll (1992), Brutsaert (1994), Shevenell (1996), Long and Derickson (1999), among others. Different approximations have also been proposed considering inclined aquifer floor, as proposed by Boussinesq (see Eq.…”

Karst Aquifer Recharge: Comments on Somaratne, N. Characteristics of Point Recharge in Karst Aquifers. Water 2014, 6, 2782–2807

“…In karst systems with significant secondary porosity, the specific yield (Sy) that underpins the WTF approach may not be a single, unique value. Shevenell [19] demonstrates that karst systems with well-developed conduits may have three alternative Sy values, one each for the fractured, matrix and conduit systems, and these can vary by an order of magnitude. As such, any localized recharge may produce a series of groundwater waves through the aquifer, travelling at different rates through the various pathways, thereby producing complex watertable response-recharge relationships.…”