Open pit mines left many regions worldwide inhospitable or uninhabitable. Many sites are left behind in a hazardous or contaminated state, show remnants of waste, or have other restrictions imposed upon them, e.g., for the protection of human or nature. Such information has to be permanently managed in order to reuse those areas in the future. In this work we present and evaluate an automated workflow for supporting the post-mining management of former lignite open pit mines in the eastern part of Germany, where prior to any planned land reuse, aforementioned information has to be acquired to ensure the safety and validity of such an endeavor. Usually, this information is found in expert reports, either in the form of paper documents, or in the best case as digitized unstructured text—all of them in German language. However, due to the size and complexity of these documents, any inquiry is tedious and time-consuming, thereby slowing down or even obstructing the reuse of related areas. Since no training data is available, we employ active learning in order to perform multi-label sentence classification for two categories of restrictions and seven categories of topics. The final system integrates optical character recognition (OCR), active-learning-based text classification, and geographic information system visualization in order to effectively extract, query, and visualize this information for any area of interest. Active learning and text classification results are twofold: Whereas the restriction categories were reasonably accurate (>0.85 F1), the seven topic-oriented categories seemed to be complex even for human annotators and achieved mediocre evaluation scores (<0.70 F1).


Example of a typical documentation. Part of the textual reports are passages about restrictions or prohibitions in the described area. (The background image consists of two photos, one by sludgeulper (left background, CC BY-SA 2.0), and the other by Johannes Kazah (right background, CC BY-SA 2.0). The resulting image changes the originals only by adding overlays (to the front) and is also licensed under the CC BY-SA 2.0 license.)
(A) Two geographic features of type 'active dismantling' are displayed on a map. One feature was selected by mouse click (orange striped texture). The weather map is shown as isobands, with precipitation values represented by shades of blue (dark blue tones indicate areas with high precipitation values). The information panel is displayed on the right hand side. It contains the non-spatial data of the selected geographic feature (B), as well as the usage restrictions together with a list of other features with similar usage restrictions (C).

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