TY - JOUR

T1 - Combined influence of weir construction and sea-level rise on freshwater resources of a coastal aquifer in northern Germany

AU - Yang, Jie

AU - Graf, Thomas

AU - Ptak, Thomas

N1 - Funding information: This research was supported by the Helmholtz Research Program “Terrestrial Environment”, topic 3: “Sustainable Water Resources Management”, with the integrated project: “Water and Matter Flux Dynamics in Catchments”.

PY - 2019/11/13

Y1 - 2019/11/13

N2 - A significant volume of an aquifer along the coastline in the German Bight is salinized by seawater intrusion. The mean sea-level rise (MSLR) is expected to continue in the future due to global climatic change, subsequently degrading the fresh groundwater resources. To impede further salinization in the future, a solution is proposed based on weir construction in an existing canal hydraulically connected to the aquifer. The effect is twofold: (1) the elevated groundwater level can upgrade present fresh groundwater resources by shifting the saltwater–freshwater interface position further seaward, or by inhibiting its landward movement, and (2) the inland water level can be elevated, expanding surface water ponds. A fully coupled three-dimensional numerical surface-subsurface model (a modified HydroGeoSphere code) was used to simulate the effects of variable weir construction heights under different MSLR rates, and to quantify the gain of aquifer freshwater volume and loss of usable land due to surface ponding. Construction of a higher weir increases the desalinized aquifer volume and decreases the newly salinized aquifer volume under future MSLR. A minimum height of a weir was determined under a certain MSLR rate to maintain the present freshwater resource. Both weir construction and MSLR can cause the loss of land usage. Computed loss-gain ratio curves can be utilized to determine the optimal weir height, meeting the economic requirements of coastal land management under future MSLR.

AB - A significant volume of an aquifer along the coastline in the German Bight is salinized by seawater intrusion. The mean sea-level rise (MSLR) is expected to continue in the future due to global climatic change, subsequently degrading the fresh groundwater resources. To impede further salinization in the future, a solution is proposed based on weir construction in an existing canal hydraulically connected to the aquifer. The effect is twofold: (1) the elevated groundwater level can upgrade present fresh groundwater resources by shifting the saltwater–freshwater interface position further seaward, or by inhibiting its landward movement, and (2) the inland water level can be elevated, expanding surface water ponds. A fully coupled three-dimensional numerical surface-subsurface model (a modified HydroGeoSphere code) was used to simulate the effects of variable weir construction heights under different MSLR rates, and to quantify the gain of aquifer freshwater volume and loss of usable land due to surface ponding. Construction of a higher weir increases the desalinized aquifer volume and decreases the newly salinized aquifer volume under future MSLR. A minimum height of a weir was determined under a certain MSLR rate to maintain the present freshwater resource. Both weir construction and MSLR can cause the loss of land usage. Computed loss-gain ratio curves can be utilized to determine the optimal weir height, meeting the economic requirements of coastal land management under future MSLR.

KW - Coastal aquifers

KW - Germany

KW - Numerical modeling

KW - Sea level rise

KW - Weir construction

UR - http://www.scopus.com/inward/record.url?scp=85068989512&partnerID=8YFLogxK

U2 - 10.1007/s10040-019-02009-9

DO - 10.1007/s10040-019-02009-9

M3 - Article

AN - SCOPUS:85068989512

VL - 27

SP - 2695

EP - 2705

JO - Hydrogeology journal

JF - Hydrogeology journal

SN - 1431-2174

IS - 7

ER -