Abstract
The article “Karst aquifer recharge: Comments on ‘Characteristics of Point Recharge in Karst Aquifers’, by Adrian D. Werner, 2014, Water 6, doi:10.3390/w6123727” provides misrepresentation in some parts of Somaratne [1]. The description of Uley South Quaternary Limestone (QL) as unconsolidated or poorly consolidated aeolianite sediments with the presence of well-mixed groundwater in Uley South [2] appears unsubstantiated. Examination of 98 lithological descriptions with corresponding drillers’ logs show only two wells containing bands of unconsolidated sediments. In Uley South basin, about 70% of salinity profiles obtained by electrical conductivity (EC) logging from monitoring wells show stratification. The central and north central areas of the basin receive leakage from the Tertiary Sand (TS) aquifer thereby influencing QL groundwater characteristics, such as chemistry, age and isotope composition. The presence of conduit pathways is evident in salinity profiles taken away from TS water affected areas. Pumping tests derived aquifer parameters show strong heterogeneity, a typical characteristic of karst aquifers. Uley South QL aquifer recharge is derived from three sources; diffuse recharge, point recharge from sinkholes and continuous leakage of TS water. This limits application of recharge estimation methods, such as the conventional chloride mass balance (CMB) as the basic premise of the CMB is violated. The conventional CMB is not suitable for accounting chloride mass balance in groundwater systems displaying extreme range of chloride concentrations and complex mixing [3]. Over simplification of karst aquifer systems to suit application of the conventional CMB or 1-D unsaturated modelling as described in Werner [2], is not suitable use of these recharge estimation methods.
Highlights
The article of Werner [2], “Karst Aquifer Recharge: Comments on Characteristics of Point Recharge in Karst Aquifers”, contains inappropriate over-simplifications of the hydrogeology and recharge processes in Uley South basin
ULE139 (Figure 6b) drilled as an investigation well in 1961 and completed as a Quaternary Limestone (QL) aquifer monitoring well shows no evidence of salinity stratification suggesting no influence by Tertiary Sand (TS) water or connection to sinkholes through conduit
Understanding recharge mechanisms and reliable recharge estimates is critical to evaluation and management of water resources
Summary
The article of Werner [2], “Karst Aquifer Recharge: Comments on Characteristics of Point Recharge in Karst Aquifers”, contains inappropriate over-simplifications of the hydrogeology and recharge processes in Uley South basin. One-dimensional unsaturated flow modelling, arrives at distorted characteristics of the Uley South. The simplistic conceptual model in Werner [2], appears “fit-for-purpose” for demonstrating the general application of the conventional CMB and 1-D unsaturated flow modelling, but is far removed from the reality of the basin. Werner [2] describes the conceptual model and well-mixed groundwater system in the QL aquifer without providing supporting evidence, substantial lithological, hydrogeological, hydrochemical and salinity profile data are available. For reader convenience, this reply is sub-divided into two sections as in Werner [2]: (1) Uley South Recharge Processes; and (2) Uley.
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