{'fraction_non_alphanumeric': 0.02237136465324385, 'fraction_numerical': 0.0, 'mean_word_length': 5.610837438423645, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Coastal monitoring with LiDAR: challenges, problems, and pitfalls

The National Assembly for Wales (NAW) is responsible for monitoring the effects of dredging for fine aggregate from sandbanks off the coast of South Wales. A key monitoring objective is the analysis of changes to the sandbank bathymetry and the adjacent coastline. This paper reviews the monitoring strategy, with a particular emphasis on the use of laserscanning with LiDAR over the last six years for large-scale topographic beach mapping and analysis. The focus is on the methodologies that were implemented in order to make the data compatible, consistent and usable within a geographical information system (GIS). The issues that are addressed include data handling strategies; automatic error/blunder detection of spurious data; identifying sources of errors; projection and datum transformations; LiDAR artefacts; quality control; choice of digital terrain model and spatial resolution; choice of interpolation algorithm; the calibration of LiDAR surveys to ensure consistency; and LiDAR accuracy compared with land surveys. Some of these issues have proved problematic, which if not correctly resolved, can produce significant application errors, thus reducing confidence in this technology. The paper concludes with some examples of the analyses undertaken to date.