LiDAR and 2D Electrical Resistivity Tomography as a Supplement of Geomorphological Investigations in Urban Areas: a Case Study from the City of Wrocław (SW Poland)

Abstract

Abstract-In urbanized areas, particularly in lowland terrains and floors of large river valleys, the natural land configuration is often hard to recognize due to a long history of human activity. Accordingly, archaeological works in cities, which supply knowledge on settlement conditions, are usually accompanied by geological and geomophological research. Lately, data from light detection and ranging (LiDAR) have become a valuable source of information on urban land configuration. Geophysical methods are also becoming increasingly popular in background studies. The paper presents a method of using and linking these sources of spatial information about landforms in such areas. The main aim is to identify to what extent these complementary sources of data and the proposed method can be used in such a specific environment to reconstruct natural, buried terrain morphology. The city of Wrocław in Central Europe serves as an example. To this end geomorphometric studies were conducted with the use of digital elevation models (DEMs) based on LiDAR scanning and derivated land-surface parameters-SAGA Wetness Index, Channel Network Base Level and Altitude above Channel Network. The study also involved determining morphological edges and measurements of the meanders of the Odra, as well as expanding information on the spatial distribution of alluvia and the structure of slope breaks. To this end, geophysical measurements were conducted using the Two-Dimensional Electrical Resistivity Tomography method. Additionally, five typical sequences of man-made ground present within the perimeter of the city were distinguished. As a result, a map of the main landforms of Wrocław is presented. Finally, we argue that although high resolution DEM and derivate land-surface parameters are very useful in terrain analysis, places with thick man-made ground or strongly levelled areas must be recognized by geoarchaeological excavations or geological bore holes. The geophysical survey is useful to identify buried morphological edges and older relief elements in open areas.

Urban Geomorphological Heritage. An Overview

“…Fundamental are methods aimed at integrating survey data, historical maps, aerial photographs and archaeological findings (e.g. Kasprzak, Traczyk 2014. The analysis of historical changes can help understanding how geomorphology ruled transformations and how it will do so in the future (Stäuble et al 2008).…”

Electrical resistivity tomography (ERT) of pit-and-mound microrelief, Mt Rogowa Kopa case study, the Stołowe Mountains, SW Poland

“…This method, which combines advantages of electrical resistivity sounding and traversing, together with modern software used in post-processing of measuring data has been applied to detect for instance: various forms developed due to the growth of ground ice within pit-bogs of the Karkonosze summit area (Dohnal et al 1999), landslide hillslopes in the Kamienne Mts. (Migoń et al 2010), complexity of the Sudetic Marginal Fault zone (Štěpančíková et al 2011), characteristics of alluvial sediments (Kasprzak, Traczyk 2013).…”

Classification of Landforms for Digital Soil Mapping in Urban Areas Using LiDAR Data Derived Terrain Attributes: A Case Study from Berlin, Germany

“…This made it very difficult to identify the original morphological or geological formations within urban areas [51]. This in turn makes geomorphological studies as well as soil studies in such areas difficult [52]. Therefore, this study investigates the possibility of classifying soil-landforms in urban areas based on analysis of geomorphometric features derived from very high-resolution LiDAR data.…”