Master thesis

Miguel Alonzo Moreno Gomez (2015)
Methods for characterization of soil hydraulic properties and subsurface stratigraphy with application at an infiltration site in Pirna, Germany. Master thesis, Technische Universität Dresden, February 2015

ABSTRACT

Hydraulic conductivity (Ks) plays an inportant rol for the processes of transport of mass and solutes through the sub-soil. Its determination is critical to determine hydrological solutions, potencial hazards and aquifer modelling. Future experimental research as part of the works to be realized by the Junior Research Group INOWAS increase the necessity of a proper soil characterization and determination of the study area hydraulic properties to determine an optimal location for an infiltration trench. In order to evaluate soil hydraulic conductivities, different methods were applied for its determination. A total of 37 samples collected from 8 boreholes were evaluated toguether with samples obtained from a trench and the performance of grain size analysis and sedimentation test to obtain important and necessary parameters for Ks calculation. Four empirical formulas were used to obtain Ks values in addition of permeameter and infiltration test by means of double ring infiltrometers (DRI). Furthermore, a laboratory evaporation method device was applied to obtain water retention curves and estimated unsaturated hydraulic conductivity values (Kun). Comparison between different approches to determine Ks was performed and variance analysis (ANOVA) was perform to determine statistically significant differences betwen the applied methods. A good correlations between empirical equations was observed although Ks values differ for some order of magnitude. Moreover, good distributions were found between infiltration tests and Ks values calculated a 2 m depth. As expected, differences between methods were found varying form 1 to 4 orders of magnitude. Differences between methods developed with undisturbed samples increase uncertainty about which one could be more accurate. To solve this problem, comparison with previous Direct Push Injection Logger test (DPIL) and the different methods was applied. Ks obtained by DPIL show a relatively high correlation with Ks values determined by water retention curves while differences with other methods display variabilities of several orders of magnitude. Therefore, further studies for comparison between these methods will be highly valuable.