ALBERT

Description: Remote sensing technology enables detecting, acquiring, and recording certain information about objects and locations from distances relative to their geographic locations. Airborne Lidar bathymetry (ALB) is an active, non-imaging, remote sensing technology for measuring the depths of shallow and relatively transparent water bodies using light beams from an airborne platform. In this study, we acquired Lidar datasets using near-infrared and visible (green) wavelength with the Leica Airborne Hydrography AB Chiroptera-I system over the Devils River basin of southwestern Texas. Devils River is a highly groundwater-dependent stream that flows 150 km from source springs to Lake Amistad on the lower Rio Grande. To improve spatially distributed stream bathymetry in aquatic habitats of species of state and federal conservation interest, we conducted supplementary water-depth observations using other remote sensing technologies integrated with the airborne Lidar datasets. Ground penetrating radar (GPR) mapped the river bottom where vegetation impeded other active sensors in attaining depth measurements. We confirmed the accuracy of bathymetric Lidar datasets with a differential global positioning system (GPS) and compared the findings to sonar and GPR measurements. The study revealed that seamless bathymetric and geomorphic mapping of karst environments in complex settings (e.g., aquatic vegetation, entrained air bubbles, riparian zone obstructions) require the integration of a variety of terrestrial and remotely operated survey methods. We apply this approach to Devils River of Texas. However, the methods are applicable to similar streams globally.

Description: Manors are an important component of the cultural-economic history of Northern Germany and Southern Scandinavia. We present the results of a geophysical prospection that led to the identification of a previously unknown manor near the village of Noer, Schleswig-Holstein, Northern Germany. Although magnetic gradiometry provides a fast way to cover large areas, it does not provide accurate depth estimates, is affected by magnetic blanking and is unable to detect differences in water content. Therefore, we applied a combination of different geophysical methods to optimize the non-invasive reconstruction of the target and its surroundings not only with respect to building structures but also in relation to the surrounding landscape. In particular, a combination of magnetics, ground-penetrating radar (GPR), electromagnetic induction (EMI), electrical resistivity tomography (ERT), and soil samples were carried out to determine: (1) the object's exact location; (2) the building structure and state of preservation; and (3) any additional structures in the surrounding area. We detected a tripartite building of 22 by 27 m, with several inner walls, which was located underneath a topographic high on the surveyed field. The bulk structure is identifiable most clearly in the magnetic and EMI inphase component maps. GPR profiles and soil samples indicate flooring or foundations in part of the building. Their shallow depths of less than 2 m below the surface and debris clusters close to the surface indicate at least partial demolition. A surrounding wall was found about 5 m outside the building. The area in between shows no magnetic anomalies, lower resistivities in EMI and ERT, and low GPR reflection amplitudes. Soil samples suggest a moat or other water feature. Archaeological artifacts found at the location characterize the building as a 16th to 17th century brick manor. Other objects, like a suspected farmyard and access path could not be found. A comparison with historical sources suggest that the mansion is in relation to the manor Grönwohld. After a change of the owner it was degraded to a Meierhof, and subsequently the building decayed and was forgotten.