Mean thermal conductivity Brandenburg

These maps are based on the legend units of the ground overview map (BÜK300) with Corresponding assignment of parameterized surface soil shapes. These represent a soil-forming society per unit of legend. The individual surface soil forms (FBF) were determined with soil physical characteristics, which were determined by terrain and laboratory tests. For the same horizon-substrate combinations (HSK), the characteristics soil type dry density, total pore volume, water content at field capacity (FK) and permanent wilting point (PWP), humus content were statistically derived (usually median values). The thermal conductivity (λ) determines the property of the soil, thermal energy by transporting the conduction. It is the decisive parameter for the use of the soil as a heat source and storage and must be taken into account, among other things, in the application of near-surface geothermal energy (earth heat collectors) or in the construction of underground power cables. To calculate the thermal conductivity, the pedotransfer function (PTF) according to Markert et al. (2017) taking into account the above characteristics. This PTF is based on extensive thermal conductivity measurements for a wide range of soils found in Brandenburg. For each HSK, the thermal conductivity for the water contents at FK and PWP has been calculated to a depth of 2m. For HSK in the area of influence of groundwater (Gr horizons), the thermal conductivity for full water saturation was estimated. Due to the parameterization of the PTF for exclusively mineral soils, the following adjustments were made: for organic HSK (peat), a thermal conductivity of λFK = 0.4 W/m*K and λPWP = 0.2 W/m*K was calculated (see measured values of Markert et al. 2017; VKR 1.32 AG Soil 2010), the parameters of the loamy soils have been used for clay soils due to the low data situation, the humus content has been taken into account by λhumos = λmineral – humus content*0.05. Due to insufficient measured values and missing information in the literature, no calculation of thermal conductivity was possible for HSK with anthropogenic starting rock. In this case, the thermal conductivity per surface soil shape has been determined as a weighted harmonic mean taking into account the thickness of all horizons. For better clarity and interpretability of the results, the weighted harmonic mean values of the thermal conductivity were divided into the following 6 classes: Thermal conductivity [W/m*K] extremely low ≤ 0.4 very low 0.41 - 0.90 Low 0.91 - 1.40 medium 1.41 - 1.90 high 1.91 - 2.40 very high 2.41 - 2.90 For the graphical representation as a map, the surface soil shapes with the same thermal conductivity class were summarized per unit of legend (LE), the area fractions of which were added per LE according to Table 66 (AG Boden 2005) and shown as an aggregated dominant and an aggregated subdominant λ-FBF. For a few areas with a very heterogeneous composition of the surface soil forms, three λ-FBF are given.