Preliminary analysis of sand transport measurements at Noordwijk site, North Sea

Abstract

Massive mining of sand from the middle and lower shoreface (depths of 10-30 m) in large-scale mining and borrow pits will be required in future in many European countries to nourish coastal beaches and dunes in response to increased coastal erosion due to expected sea level rise. The offshore mining of sand will require fundamental knowledge of morphological and sand transport processes at deep water (middle and lower shoreface). At present stage of research our understanding of these processes, especially sand transport, is not sufficient to assess the impact of massive sand mining. Therefore, research on sand transport, focusing on middle and lower shoreface, is a key topic within the EU-Sandpit project. The overall objective of the EU-Sandpit project is to develop reliable prediction techniques and guidelines to better understand, simulate and predict the morphological behaviour of large-scale sand mining pits and the associated sand transport processes at the middle and lower (offshore) shoreface and also surrounding coastal zone. The emphasis is on the role of large-scale offshore sand mining pits, but the morphological behaviour of dredged channels and trenches for navigation, pipelines and telecom-cables will also be addressed. The potential use of large-scale sand banks and shoals for sand mining will also be studied. Furthermore, the ecological effects of sand mining and dredging will be evaluated and summarized. In the framework of the EU-Sandpit project, field measurements of hydrodynamics and sediment transport were done in March/April and September/October 2003 at 2 km off the coast of Noordwijk aan Zee, the Netherlands. The field data will be used to improve, calibrate and validate sediment transport models and morphodynamic models. The present report provides an overview of the hydrodynamic and sediment transport data measured with the HSM tripod of the University of Utrecht during the first weeks of the EU-Sandpit measurement campaigns. Measurements with various other instruments were also done during these campaigns and are described in separate contributions. Besides the detailed time series given in this report, the measured data are clustered into 33 groups of similar wave heights and current velocities to simplify the use for modellers. Clustering significantly reduces the amount of data and clearly illustrates the general trends in the data.