Abstract: Despite that fractured coastal aquifers are widespread, the influence of fracture characteristics on seawater intrusion (SWI) has not been explored in previous studies. This research uses numerical modelling in a first step towards understanding the influence of fracture orientation, location and density on the extent of seawater and accompanying patterns of groundwater discharge in an idealised coastal aquifer. Specifically, aquifers containing single fractures or networks of regularly spaced fractures are studied using modified forms of the Henry SWI benchmark problem. The applicability of equivalent porous media (EPM) models for representing simple fracture networks in steady-state simulations of SWI is tested. The results indicate that the influence of fractures on SWI is likely to be mixed, ranging from enhancement to reduction in seawater extent and the width of the mixing zone. For the conceptual models considered here, vertical fractures in contact with the seawater wedge increase the width of the mixing zone, whereas vertical fractures inland of the wedge have minimal impact on the seawater distribution. Horizontal fractures in the lower part of the aquifer force the wedge seaward, whereas horizontal fractures located within the zone of freshwater discharge enhance the wedge. Inclined fractures roughly parallel to the seawater-freshwater interface increase the landward extent of seawater and fractures perpendicular to the interface inhibit the wedge. The results show that EPM models are likely inadequate for inferring salinity distributions in most of the fractured cases, although the EPM approach may be suitable for orthogonal fracture networks if fracture density is high and appropriate dispersivity values can be determined.

Abstract: Soil salinization is an environmental problem having
significant impacts on the soil–water–plant system. This
problem is more frequent in coastal areas due to seawater
intrusion into the land. Assessing the soil salinization is a
critical issue for the agricultural areas situated in the
Mediterranean basin. This paper examines the deterioration
of soil quality in the cultivated land of a Mediterranean site
(Agoulinitsa district—West Greece). Soil samples were collected
in both pre-irrigation and post-irrigation seasons.
Electrical conductivity (EC), pH and the ions Br−, Ca2+, Cl−,
F−, K+, Li+, Mg2+, Na+, NH4
+, NO2
−, NO3
−, PO4
3− and SO4
2−
were determined by the 1:2 (soil/water ratio on weight basis)
method. The salts which were present in both seasons in the
soils of the area studied are KCl, MgCl2, NaCl, CaSO4 and
K2SO4. The wide spatiotemporal variation of EC in the cultivated
land in both seasons demonstrates that soil salinity is
controlled mainly by seawater intrusion and anthropogenic
factors such as the application of salt-rich water which is
directly pumped from the drainage ditches. Seawater intrusion
provides the affected soil with elevated contents of Ca2+, Cl−,
K+, Mg2+, Na+ and SO4
2−. Classification of the soils by using
criteria given by the literature is discussed. Practices to prevent,
or at least ameliorate, salinization in the cultivated land
of Agoulinitsa district are proposed.