DOI: 10.5880/gfz.4.4.2020.004
title: Soil physical and hydraulic properties along two chronosequences of proglacial moraines

description: The data set ": Soil physical and hydraulic properties along two chronosequences of proglacial moraines" consists of several individual files in tabstop delimeted text format. The data set contains soil physical data from two chronosequences of moraines in glacier forefields in the central Alps, Switzerland. Aim of the study was to investigate the impact of age and parent material on soil physical characteristics. At the forefield of the Stone Glacier the moraines developed from silicate parent material (S) and at the forefield of the Griessfirn from calcareous parent material (C). At each forefield disturbed and undisturbed soil samples were collected from four moraines of different ages and porosity, bulk density, particle size distribution, gravel content, ignition loss, retention curves and unsaturated hydraulic conductivity curves were determined. Per moraine, three sampling sites were identified based on the level of vegetation complexity [low, medium, high] (for details on this vegetation classification see Maier et al., 2019). Two sampling locations spaced 3 to 4 m apart were selected per vegetation complexity at each moraine. These different sampling locations are identified in the files as location 1 and 2. Data sets from the moraines developed from silicate parent material are marked with S and data from the moraines with calcareous parent material are marked with C. For the C forefield bulk density, porosity and ignition loss are listed in a single file. For the S location the ignition loss data is listed in a separate file from the bulk density and porosity data. In each file the sample type, the sample volume, the sample number, the moraine age, the sampling depth, and the level of vegetation complexity are provided. The particle size distributions of the fine earth and the gravel content are also listed in individual files. Again, the sample number, moraine age, vegetation complexity, sampling depth and sampling location are noted in the files. For the retention curves and the unsaturated hydraulic conductivity curves, two files exist for each curve and glacier forefield, which are named accordingly with the glacier forefield identification and type of curve. An overview file for each glacier forefield contains a list with the sample number, moraine age, sampling depth, vegetation complexity and sampling location. The other two files per curve contain the lab measurements. For the retention curve data, the sample numbers link the pressure head [cm] values provided in one file to the corresponding volumetric water content [-] values provided in the other file. The same applies to the hydraulic conductivity curve where the sample number now links the unsaturated hydraulic conductivity [cm/h] to the corresponding pressure head [cm].
description: Three types of soil cores were used for soil sampling (due to different size requirements of the lab equipment). The core types are noted as a, b, and c. a-samples have a diameter of 5.8 cm, a height of 4 cm, and a volume of 100 cm³. Type b- and c-samples each have a volume of 250 cm³. The diameter of b-samples is 7.2 cm and the height is 6.1 cm. c-samples have a diameter of 8 cm and a height of 5 cm. All bulk density and porosity were measured using undisturbed soil samples of types a, b, and c. The porosity was determined by using the water saturation method and weighing the samples at saturation and after drying at 105 °C. The loss on ignition was determined by drying sub-samples (4-6 g) for at least 24 hours at 105 °C and then at 550 °C. The ignition loss is then calculated by relating the weight loss after drying at 550 °C to the sample weight after drying at 105 °C. Bulk density was determined by relating the sample weight after drying at 105 °C to the sample volume. The particle size distributions of the fine earth were derived using disturbed soil samples and a combination of dry sieving (particles &gt; 0.063 mm) and sedimentation analysis (particles &lt; 0.063 mm) with the hydrometer method. Particles between 2 mm and 0.063 mm were classified as sand, between 0.063 mm and 0.002 mm as silt and &lt; 0.002 mm as clay. Particle size fractions were calculated as weight percentages of the fine earth (&lt; 2 mm), thus excluding gravel and stones to avoid that single larger stones shift or dominate the distribution. The gravel and stone fraction (particles &gt; 2 mm) was calculated separately as a weight percentage of the entire soil sample. The soil hydraulic properties in the form of the retention curve and the unsaturated hydraulic conductivity curve were measured based on the experimental evaporation method (Schindler and Müller, 2006) using undisturbed soil core samples of type b. The data analysis was carried out according to Peters and Durner (2008).