Institute of Geography, Leipzig University, Leipzig, Germany.
Seminar of the Archaeology of Prehistory to the Early Middle Ages, Friedrich-Schiller University, Jena, Germany.
PLoS One. 2018 Jul 5;13(7):e0200167. doi: 10.1371/journal.pone.0200167. eCollection 2018.
The use of remote sensing techniques to identify (geo)archaeological features is wide spread. For archaeological prospection and geomorphological mapping, Digital Terrain Models (DTMs) on based LiDAR (Light Detection And Ranging) are mainly used to detect surface and subsurface features. LiDAR is a remote sensing tool that scans the surface with high spatial resolution and allows for the removal of vegetation cover with special data filters. Archaeological publications with LiDAR data in issues have been rising exponentially since the mid-2000s. The methodology of DTM analyses within geoarchaeological contexts is usually based on "bare-earth" LiDAR data, although the terrain is often significantly affected by human activities. However, "bare-earth" LiDAR data analyses are very restricted in the case of historic hydro-engineering such as irrigation systems, mills, or canals because modern roads, railway tracks, buildings, and earth lynchets influence surface water flows and may dissect the terrain. Consequently, a "natural" pre-modern DTM with high depth accuracy is required for palaeohydrological analyses. In this study, we present a GIS-based modelling approach to generate a pre-modern and topographically purged DTM. The case study focuses on the landscape around the Early Medieval Fossa Carolina, a canal constructed by Charlemagne and one of the major medieval engineering projects in Europe. Our aim is to reconstruct the pre-modern relief around the Fossa Carolina for a better understanding and interpretation of the alignment of the Carolingian canal. Our input data are LiDAR-derived DTMs and a comprehensive vector layer of anthropogenic structures that affect the modern relief. We interpolated the residual points with a spline algorithm and smoothed the result with a low pass filter. The purged DTM reflects the pre-modern shape of the landscape. To validate and ground-truth the model, we used the levels of recovered pre-modern soils and surfaces that have been buried by floodplain deposits, colluvial layers, or dam material of the Carolingian canal. We compared pre-modern soil and surface levels with the modelled pre-modern terrain levels and calculated the overall error. The modelled pre-modern surface fits with the levels of the buried soils and surfaces. Furthermore, the pre-modern DTM allows us to model the most favourable course of the canal with minimal earth volume to dig out. This modelled pathway corresponds significantly with the alignment of the Carolingian canal. Our method offers various new opportunities for geoarchaeological terrain analysis, for which an undisturbed high-precision pre-modern surface is crucial.
遥感技术在识别（地理）考古特征方面得到了广泛应用。对于考古勘探和地貌测绘，主要使用基于激光雷达（Light Detection And Ranging）的数字地形模型（DTM）来探测地表和地下特征。激光雷达是一种遥感工具，它以高空间分辨率扫描表面，并使用特殊的数据滤波器去除植被覆盖。自 21 世纪中期以来，发表的带有激光雷达数据的考古学出版物呈指数级增长。在地质考古学背景下，DTM 分析的方法通常基于“裸地”激光雷达数据，尽管地形通常受到人类活动的显著影响。然而，对于历史上的水利工程，如灌溉系统、磨坊或运河，“裸地”激光雷达数据的分析受到很大限制，因为现代道路、铁路轨道、建筑物和土堤会影响地表水流，并且可能会切割地形。因此，对于古水文学分析，需要具有高精度的“自然”前现代 DTM。在本研究中，我们提出了一种基于 GIS 的建模方法，以生成前现代和地形净化的 DTM。该案例研究重点关注早期中世纪福萨卡罗莱纳（Fossa Carolina）周围的景观，这是查理曼大帝建造的运河，也是欧洲主要的中世纪工程之一。我们的目标是重建福萨卡罗莱纳周围的前现代地貌，以便更好地理解和解释卡洛林运河的走向。我们的输入数据是激光雷达衍生的 DTM 和一个全面的人工结构矢量层，这些结构会影响现代地貌。我们使用样条算法对剩余点进行插值，并使用低通滤波器对结果进行平滑处理。净化后的 DTM 反映了景观的前现代形状。为了验证和实地检验模型，我们使用了被洪泛区沉积物、冲积层或卡罗林运河坝材料掩埋的前现代土壤和地表的水平。我们将前现代土壤和地表的水平与建模的前现代地形水平进行了比较，并计算了总误差。建模的前现代地表与埋藏土壤和地表的水平吻合。此外，前现代 DTM 使我们能够用最小的挖掘土方量来模拟最有利的运河路线。这条模拟的路径与卡罗林运河的走向非常吻合。我们的方法为地质考古地形分析提供了各种新的机会，其中关键是需要一个未受干扰的高精度前现代表面。
