Multimodal and Multitemporal Drone Remote Sensing Approaches to Archaeological Prospection: The Case Study at the Medieval Castle of ‘t Huis ten Bosch, Weesp, The Netherlands

This article evaluates the contribution of multi-temporal UAV remote sensing to archaeological prospection in a Dutch grassland context, using the moated castle site of ’t Huis ten Bosch as a detailed case study. Six UAV campaigns, spanning more than four years and deploying thermal, multispectral, RGB and LiDAR sensors, are compared with magnetometry, electromagnetic induction, and coring data, and evaluated against seasonal and atmospheric conditions. The combined dataset corroborates and refines the subsurface record of the primary moat, secondary moat, and central tower and walls, demonstrating that no single prospection technique, applied in isolation, could have produced the same level of structural detail and interpretative confidence. A systematic comparison of anomaly visibility across campaigns shows that detectability varied considerably between campaigns, tracking soil properties, moisture history, vegetation phenology, and mowing regime, with the clearest results tending to coincide with transitional meteorological conditions instead of prolonged extremes, on the evidence of six campaigns. The study highlights both the promise and the site-specific constraints of UAV-based prospection, and identifies methodological limitations related to sensor availability, campaign density, and the use of regional meteorological data. It concludes by outlining some provisional best practices for UAV survey design and by arguing for stratified, multi-site implementations to develop a comparative empirical basis for optimising sensor deployment in archaeological prospection in the Netherlands and beyond.