The Delineation of Paleo-Shorelines in the Lake Manyara Basin Using TerraSAR-X Data

Abstract

Abstract:The purpose of this paper is to describe the delineation of paleo-shorelines using high resolution microwave images and digital image processing tools, and with that to contribute to the understanding of the complex landscape evolution of the Lake Manyara Basin. The surroundings of Lake Manyara are the focus of several paleo-archeological investigations, since the location is close to Olduvai Gorge, where paleo-anthropological findings can be traced back to homo habilis. In the catchment of Lake Manyara two hominin-bearing sites (0.78 to 0.63 Ma), lots of vertebrate fossils and hand axes from different periods were found. Understanding the development and extent of the lake is crucial for understanding the regional paleo-environment of the Quaternary. Morphological structures of shorelines and terraces east of Lake Manyara were identified from TerraSAR-X StripMap images. By applying a Canny edge detector, linear features were extracted and revised for different image acquisitions using a contextual approach. Those features match literature and field references. A digital elevation model of the region was used to map the most distinct paleo-shorelines according to their elevation.

Evaluating the Quality and Accuracy of TanDEM-X Digital Elevation Models at Archaeological Sites in the Cilician Plain, Turkey

“…Compared to this, the present VHR SAR systems provide operational data products and worldwide coverage at high temporal frequency and spatial resolution. Recent studies have underlined the substantial potential of VHR SAR for the recognition of archaeological features and historical morphological structures (e.g., [21,22]). Others have demonstrated the added value of SAR features like polarimetry and multifrequency for the identification of buried objects [23,24].…”

Comparative analysis of Edge Detection techniques for SAR images

“…2). The most prominent shorelines can be found at different elevations of 970 m, 978 m, 1002 m to 1008 m, 1018 m and 1030 m above sea level [Bachofer et al, 2014]. These paleo-shorelines were formed in more humid phases during the Quaternary when the lake level was higher.…”

“…Optical remote sensing methods failed to delineate the above mentioned paleolake features due to spectral similarities with the surface in the vicinity. Hence, we utilized the backscatter intensity information from TerraSAR-X StripMap [Bachofer et al, 2014]. The morphological structures of shorelines and terraces east of Lake Manyara are characterized by high Synthetic Aperture Radar (SAR) backscatter values, due to their distinct geometric structure and texture (high share of gravel).…”

“…Remote sensing analysis in paleo-landscape research is a widely used and accepted method. The combination of satellite image data with digital elevation models (DEM) was applied to delineate paleolakes and paleolake related features Gaber et al, 2009;Elmahdy, 2012;Bachofer et al, 2014]. SAR data was used for the mapping of geological features and paleo-landscape in different studies [Dabbagh et al, 1997;Schaber et al, 1997;Abdelsalam et al, 2000].…”

Multisensoral Topsoil Mapping in the Semiarid Lake Manyara Region, Northern Tanzania

“…For this period, the average annual precipitation of 651 mm is mainly caused by two wet seasons. One occurs between November and January and a second between March and May [45]. This results in a sparsely-vegetated semiarid environment dominated by bushy grassland.…”