Interpreting gaps: a geoarchaeological point of view on the Gravettian record of Ach and Lone valleys (Swabian Jura, SW Germany)

Unlike other Upper Paleolithic industries, Gravettian assemblages from the Swabian Jura are documented solely in the Ach Valley (35-30 Kcal BP). On the other hand, traces of contemporaneous occupations in the nearby Lone Valley are sparse. It is debated whether this gap is due to a phase of human depopulation, or taphonomic issues related with landscape changes. In this paper we present ERT, EC-logging and GPR data showing that in both Ach and Lone valleys sediments and archaeological materials eroded from caves and deposited above river incisions after 37-32 Kcal BP. We argued that the rate of cave erosion was higher after phases of downcutting, when hillside erosion was more intensive. To investigate on the causes responsible for the dearth of Gravettian materials in the Lone Valley we test two alternative hypotheses: i) Gravettian humans occupied less intensively this part of the Swabian Jura. ii) Erosion of cave deposits did not occur at the same time in the two valleys. We conclude that the second hypothesis is most likely. Ages from the Lone Valley show increasing multimillennial gaps between 36 and 18 Kcal BP, while a similar gap is present in the Ach Valley between 28 and 16 Kcal BP. Based on geoarchaeological data from previous studies and presented in this paper, we interpreted these gaps in radiocarbon data as indicating of cave erosion. Furthermore, we argued that the time difference across the two valleys show that the erosion of cave deposits began and terminated earlier in the Lone Valley, resulting in a more intensive removal of Gravettian-aged deposits. The hypothesis that cave erosion was triggered by regional landscape changes seems to be supported by geochronological data from the Danube Valley, which show that terrace formation at the end of the Pleistocene moved westwards throughout southern Germany with a time lag of few millennia.PTDC/HAR-ARQ/27833/2017info:eu-repo/semantics/publishedVersio

Effects of Heterogeneous Parameter Distributions on Hydraulic Tests : Analysis and Assessment

Groundwater flow and transport processes are dominated by the heterogeneity of the subsurface. In the last decades, the importance of a detailed description, characterization, and quantification of aquifer heterogeneity became more and more evident. The present work is motivated by the requirement of an improved understanding of the interrelationship of effects resulting from heterogeneity on particular measurements, and by the importance of a detailed characterization of heterogeneity. To account for these issues, two different approaches are applied: 1) Experimental tests conducted to a fractured sandstone block allowing the practical investigation of effects arising from the strongly heterogeneous nature of the sample. 2) A theoretical approach based on the analysis of sensitivity coefficients enabling the improvement of the theoretical comprehension of effects arising from aquifer heterogeneity. The experimental investigation of the fractured porous rock shows effects arising from the heterogeneity of the fractured system. However, the comparison of the experimental results exemplifies the necessity of an improved understanding of the interrelation between an arbitrary parameter distribution and the response of a particular hydraulic measurement. A promising concept to account for this interrelationship is the Sensitivity Coefficient Approach (SCA). The SCA is applied to investigate the intrinsic characteristics of hydraulic tests giving a better understanding of the response of hydraulic tests due to aquifer heterogeneity. As the approach allows the assessment of information from distinct time periods during a hydraulic test, the assignment of estimated parameters to particular spatial information can succeed. Based on the SCA an alternative measuring concept is suggested for an improvement of the conventional approach of hydraulic tests. A proof of the suitability and applicability of the approach is given by numerical examples and field measurements.Groundwater flow and transport processes are dominated by the heterogeneity of the subsurface. In the last decades, the importance of a detailed description, characterization, and quantification of aquifer heterogeneity became more and more evident. The present work is motivated by the requirement of an improved understanding of the interrelationship of effects resulting from heterogeneity on particular measurements, and by the importance of a detailed characterization of heterogeneity. To account for these issues, two different approaches are applied: 1) Experimental tests conducted to a fractured sandstone block allowing the practical investigation of effects arising from the strongly heterogeneous nature of the sample. 2) A theoretical approach based on the analysis of sensitivity coefficients enabling the improvement of the theoretical comprehension of effects arising from aquifer heterogeneity. The experimental investigation of the fractured porous rock shows effects arising from the heterogeneity of the fractured system. However, the comparison of the experimental results exemplifies the necessity of an improved understanding of the interrelation between an arbitrary parameter distribution and the response of a particular hydraulic measurement. A promising concept to account for this interrelationship is the Sensitivity Coefficient Approach (SCA). The SCA is applied to investigate the intrinsic characteristics of hydraulic tests giving a better understanding of the response of hydraulic tests due to aquifer heterogeneity. As the approach allows the assessment of information from distinct time periods during a hydraulic test, the assignment of estimated parameters to particular spatial information can succeed. Based on the SCA an alternative measuring concept is suggested for an improvement of the conventional approach of hydraulic tests. A proof of the suitability and applicability of the approach is given by numerical examples and field measurements

Fiber Optic Pressure Measurements Open Up New Experimental Possibilities in Hydrogeology

Fiber-optic (FO) technology is being used increasingly for measurement methods in a variety of environmental applications. However, FO pressure transducers are rarely used in hydrogeological applications. We review the current state of Fabry-Pérot interferometry-based FO pressure transducers, including their advantages and limitations, as another option for high-resolution pressure- or head-change measurements in conventional or advanced aquifer testing. Resolution and precision specifications of FO transducers meet or exceed commonly used non-FO pressure transducers. Due to their design, FO transducers can be used in small-diameter (innerdiameter≥1/4 inch) and continuous multichannel tubing (CMT), sampling points, multilevel packer systems, and Direct Push-based in situ installations and testing. The small diameter of FO transducers provides logistical advantages — especially for tests with monitoring at many zones in a number of wells and/or CMTs (e.g., no reels, placement just below water level in access tubes vs. within isolated zones, reduced weight and volume, small footprint at single point of data acquisition). Principal limitations are small measurement drift that may become evident for tests longer than a few hours, and higher-than-average cost. We present field examples of FO transducer performance in short-term tests with high consistency of acquired data and higher resolution(i.e., capturing significant hydrologic information) compared with commonly used non-FO transducers. Given the above, including advantageous logistical features, FO transducers can open new experimental possibilities in areas of high-resolution three-dimensional (3D) heterogeneity (flow and transport, remediation, critical zones); 3Dfracture networks and fundamental hydromechanical behavior; complex 3D flow and leak detection (mines, dams, repositories, geothermal systems)

Comment on “Aquifer Characterization Using Fiber Bragg Grating Multi-Level Monitoring System”

Wang et al. (2022) describe the fiber Bragg grating (FBG) optical fiber transducer technology for pressure sensing in hydrologic testing applications, and in particular, for hydraulic tomography (HT) testing. As part of their Introduction section, Wang et al. describe attributes and published accounts of HT testing configurations with an alternative fiber-optic pressure-sensing technology using Fabry-Perot (FP) interferometry sensors or transducers. While such descriptions must be limited for space considerations, they should still be clear and correct—especially for the comparative presentation of optical fiber transducer technologies that are not yet widely used in hydrogeological applications (Leven and Barrash 2022)