Fresh groundwater resources in a large sand replenishment

Abstract

Abstract. The anticipation of sea-level rise and increases in extreme weather conditions has led to the initiation of an innovative coastal management project called the Sand Engine. In this pilot project a large volume of sand (21.5 million m 3 ) -also called sand replenishment or nourishment -was placed on the Dutch coast. The intention is that the sand is redistributed by wind, current, and tide, reinforcing local coastal defence structures and leading to a unique, dynamic environment. In this study we investigated the potential effect of the long-term morphological evolution of the large sand replenishment and climate change on fresh groundwater resources. The potential effects on the local groundwater system were quantified with a calibrated three-dimensional (3-D) groundwater model, in which both variable-density groundwater flow and salt transport were simulated. Model simulations showed that the long-term morphological evolution of the Sand Engine results in a substantial growth of fresh groundwater resources, in all adopted climate change scenarios. Thus, the application of a local sand replenishment could provide coastal areas the opportunity to combine coastal protection with an increase of the local fresh groundwater availability.

Accommodation space indicates dune development potential along an urbanized and frequently nourished coastline

“…The embryo dunes around the small dune lake, while technically located in the same elevation zone, have likely mostly established by seed germination as the high constructed base of the Zandmotor has completely blocked all storm surge impacts until now. Over the years there has been a steady build-up of a freshwater lens under the Zandmotor and the salinity of the dune lake has significantly decreased as a result (Huizer et al, 2016). This fresh water availability, in combination with moderate burial dynamics, have been shown by Konlechner et al (2013) to be beneficial to marram grass seed germination and subsequent dune establishment.…”

“…At the same time, as laid out in more detail by Jackson and Nordstrom (2011), the structure of the hospitality establishment itself may alter (i.e., block) aeolian transport from the beach and retard foredune development. This plays an even larger role in the nourished zone north of the Zandmotor where, besides a large number of hospitality establishments, a high amount of seasonal beach cabins are also placed along the toe of the foredunes from March until October (from 2016 onward).…”

“…Further, another important anthropogenic disturbance with a highly negative impact to dune development is that the beach directly north of the Zandmotor is mechanically raked during the summer to remove wrack line material and human litter. Even though it is a common practice to accommodate beach recreation (Jackson and Nordstrom, 2011), this severely hampers embryo dunes from establishing themselves on the beach. Not only can the machinery destroy any sprouting seedlings or rhizomes of marram grass, the removal of wrack deposits also deprives marram grass from potential hospitable locations to establish itself on the beach (Kelly, 2014).…”

“…Because the region is densely populated, the coastline (including the Zandmotor) faces persistent pressure from anthropogenic disturbances. Even though the Delfland coast is meant to serve a wide range of socioeconomic functions related to recreation and leisure, activities arising from these function are often in direct conflict with the objectives related to coastal safety and natural values (e.g., Jackson and Nordstrom, 2011;Lithgow et al, 2013). Within this context, this paper examines to what extent the Zandmotor has contributed to creating accommodation space favorable for dune development, i.e., accommodation space that is sheltered from frequent storm impacts and experiencing a steady accumulation of wind-blown sand.…”

Distribution of grain size and resulting hydraulic conductivity in land reclamations constructed by bottom dumping, rainbowing and pipeline discharge

“…1 The minimum and maximum grain-size distribution curves of samples taken from the Maasvlakte II, Rotterdam, the Netherlands, Palm Jumeirah, Dubai, the United Arab Emirates (Lees et al 2013), Changi Airport, Singapore, Malaysia (Chua et al 2007), Chep Lap Kok, Hong Kong, China (Lee 2001), West Kowloon, Hong Kong, China (Lee et al 1999) ubiquitous. Jiao et al (2001Jiao et al ( , 2006 and Huizer et al (2017), for instance, applied a constant porosity and conductivity for the land reclamation when they studied the increase of the freshwater volume under adjacent old land caused by land reclamations in Hong Kong, China and along the Dutch North Sea coast, respectively.…”