Design of the subsurface of land reclamations for freshwater storage and recovery: A new view on land reclamations

Abstract

Worldwide, land reclamations are constructed for the urban expansion of coastal megacities. Freshwater supply plays an important role in their sustainable development, especially in the light of climate change and depletion of natural water resources in the hinterland. The subsurface of these new lands offer opportunities for subsurface freshwater storage and recovery. Moreover, the design from scratch and construction makes it possible to not only manage the mixing and buoyancy of a freshwater volume in a saline aquifer operationally, but also to create physical properties of the subsurface to reach high recovery efficiencies. In this dissertation, three concepts have been identified that allow managing the mixing and density stratification of a freshwater volume in saline aquifers. These are: 1) the properties of these man made islands that reduce mixing and density stratification, 2) vertical flow barriers of limited depth that prevent the volume of fresh water from expanding radially, speeding up the formation of the freshwater stock, and 3) saltwater extraction from below the freshwater stock, which prevents the freshwater volume for floating up by counteracting buoyancy. Secondly, insight has been given in the internal structure of the porous media and its hydraulic properties of five land reclamations that were constructed by bottom dumping, rainbowing and pipeline discharge. The increasing number of land reclamations that result from the ongoing worldwide urbanisation of coastal areas, for which a robust freshwater supply must be guaranteed, make the results of this thesis widely applicable.