Zand in banen : zanddieptekaarten van het Rivierengebied en het IJsseldal in de provincies Gelderland en Overijssel

Abstract

Over the past decades, the Rhine-Meuse delta in the Netherlands has been studied extensively at Utrecht University. A unique dataset exists of unique potential for investigations on various aspects of fluvial sedimentology, delta geomorphology, Quaternary geology, river-engineering, hydrocarbon reservoir modeling, environmental science, hydrology, archaeology and spatial planning in fluvial-coastal plains. This potential has been increasingly recognized by various groups of users in the last decade. In 1991, the Province of Gelderland asked Utrecht University to produce a map showing ‘sand depth’ (depth to sand measured relative to surface elevation) in the fluvial area under its government. This has lead to publications of dedicated maps in 1994 (1st edition), 2001 (2nd Edition) and 2009 (this 3rd edition). A main reason to produce the maps were difficulties to optimize water management, including controlling groundwater quality and quantity, drainage, eutrophication and reconstructing canals, for which reliable knowledge of subsurface lithology and permeability was lacking. In addition to serving the purposes listed above, the map turned out useful for numerous other spatial planning applications, including archeological prospections that became obligatory following European jurisdiction (1992, Valletta, Malta). This report documents the third completely revised edition of the map. Compared to the earlier published versions of the map: * Areal coverage is much expanded. It covers the central and upper Rhine-Meuse delta and now importantly includes the north-running river Gelderse IJssel, a major branch of the Rhine delta. The map now covers virtually all the riverine area of the province of Gelderland and adjacent parts of province of Overijssel. * The 1994-mapping of channel belts in the polders of the central and upper delta has now been updated using new collected borehole data (Utrecht University and other parties) and brought in accordance with geomorphological interpretations of high resolution digital elevation data from airborne laser altimetry (AHN dataset, http://www.ahn.nl). * The documentation of the map is completely revised, integrating and updating the scientific results from 20th century, with new insights acquired in the last 10 years. * The summary in English describes the mapping methods and map legend and the geology of the study area, with focus on the differences in substrate and delta architecture between subregions (Ch 10: p. 110-115). The documented map shows categories of depth to sand, with class boundaries at every 1.0 meter. The colors used on the map differ for sands of deltaic origin, i.e. the Holocene former channel belts, sand of active channel belts with nowadays embanked floodplains (‘uiterwaarden’) and older sand flanking and underlying the deltaic deposits, of fluvial origin (Rhine braidplain, periglacial alluvial fans and valleys of local tributary systems) and of eolian origin (coversand sheets and inland dunes). The actual map is supplied in digital form on CD-ROM, as a set of PDFs for quick reference and as a GIS resource in ESRI shapefile format for professional use. It is also shared on the internet as a digital map layer within http://www.gelderland.nl/wateratlas, where the map can be viewed, printed and downloaded.