Hydrochemical evidence of fresh- and salt-water intrusions in the Coastal Dunes Aquifer System of the western Netherlands
Stuyfzand, P.J. (1989). Hydrochemical evidence of fresh- and salt-water intrusions in the Coastal Dunes Aquifer System of the western Netherlands. Natuurwet. Tijdschr. 70(1-4): 9-29
In: Natuurwetenschappelijk Tijdschrift. L. Walschot/Natuur- en Geneeskundige Vennootschap: Gent. ISSN 0770-1748, meer
Ook verschenen in:De Breuck, W.; Walschot, L. (Ed.) (1989). Proceedings of the 10th Salt-Water Intrusion Meeting Ghent (Belgium), 16-20 May 1988. Natuurwetenschappelijk Tijdschrift, 70(1-4). Natuurwetenschappelijk Tijdschrift: Gent. 408 pp., meer
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| Trefwoorden |
Saline intrusion
Topographic features > Beach features > Dunes
Water > Fresh water
Water masses > Water types
ANE, Nederland [Marine Regions]
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| Abstract |
The spatial distribution of water types, classified according to STUYFZAND (1986a, 1986b), and datings of fresh groundwater have been used, together with geological and hydrological data, to elucidate the hydrological evolution of the coastal area of the Western Netherlands. Freshening, salinizing and equilibrium water types are discerned in a longitudinal section of 100 km and in two cross sections. Freshening water types are found within the fresh-water lens mainly at three locations : (a) the central base reflecting its downward growth in the period 1000-1600 A.D., upon the formation of the young dunes; (b) its inland side, mainly due to its continuing extension in that direction, following the reclamation of brackish lakes behind the dunes in the period 1550-1900 A.D. ; and (c) elsewhere within and downstream of thick aquitards with high flow resistance, in which chloride inversions may still be present. Salinizing water types occur mainly on the coastal face of the fresh-water lens due to lateral North Sea intrusion and below its central base due to upconing. This salinization is mainly due to excessive abstraction for water supply, the exploitation of dune sand, the creation of harbours and of the North Sea canal, and urbanization. Under the reclaimed lakes, east of the freshening water types, salinizing water occurs, probably in connection with the Holocene transgression and intrusion and upconing due to intensive drainage as well as volumetric compensation for the expansion of the fresh-water lens. The extension of artificially recharged Rhine and polder waters must be considered as a salinization as well. Fresh groundwaters have been dated using 3H, 14C, 180 and the breakthrough of recharged Rhine water. In the upper aquifer and aquitard (above 20 m-MSL) ages vary from 0-70 years, in the second aquifer (20-70 m-MSL) from 25-400 years. Below an aquiclude at 100 m-MSL, 800 years old dune water was found. |
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