Saltwater Intrusion in Coastal Aquifers: A Primary Case Study along the Adriatic Coast Investigated within a Probabilistic Framework

Abstract

Abstract:Environmentally sensitive areas along coastlines may be adversely affected by saltwater intrusion (SI), a condition which can be worsened by extensive groundwater extraction. Given the uncertainty of problem parameters, the risk of contamination of the vegetation capture zone needs to be cast in a probabilistic framework. In order to exemplify real situations existing along the Adriatic coast of Emilia-Romagna, a case study involving a pinewood strip and a well field drawing freshwater from an unconfined coastal aquifer was examined. On the basis of a widely adopted sharp interface formulation, key hydrogeological problem parameters were modeled as random variables, and a global sensitivity analysis was carried out to determine their influence on the position of the interface. This analysis utilized an efficient model reduction technique based on Polynomial Chaos Expansion. The risk that saltwater intrusion affects coastal vegetation was then evaluated via a two-step procedure by computing the probability that (i) the leading edge of the saltwater wedge reaches the sensitive area in the horizontal plane, and (ii) the freshwater/saltwater interface reaches the capture zone. The influence of the design parameters of the well field on the overall probability of contamination was investigated, revealing the primary role of the pumping discharge in the examined configuration.

A Generalized Semi-Analytical Solution for the Dispersive Henry Problem: Effect of Stratification and Anisotropy on Seawater Intrusion

“…The effect of anisotropy on SWI has been often investigated using the sharp interface model [77], which assumes that freshwater and saltwater are immiscible [78][79][80][81]. Abarca et al [13] were the first to investigate the influence of anisotropy on the saltwater wedge using the DDF model.…”

Analysis of Saline Intrusion into a Coastal Aquifer: A Case History of Legacy Issues and Challenges to Water Security

“…The location of the toe of the saltwater wedge can be computed for the x-y plane from equations (5) and (14) as (Felisa et al, 2013;Naderi et al, 2013) for multiple wells:…”

“…Because of its simplicity, the analytical solution (Strack, 1976) is widely used in lieu of sophisticated numerical modelling as a first order analysis of saline intrusion problems for data limited aquifers. There are a number of analytical models available for addressing seawater intrusion problems but the use of Strack (1976) sharp interface assumption and in particular, analytical solution are widely reported (Aharmouch & Larabi, 2001;Montoglou, 2003;Morgan et al, 2013;Felisa et al, 2013;Naderi et al, 2013;Beebe et al, 2016). Since the sharp interface assumption neglects mixing, Pool & Carrera (2011) extended the analytical solution to the case of mixing zones by modifying the density factor by an empirically derived dispersion factor.…”

Integrative management of saltwater intrusion in poorly-constrained semi-arid coastal aquifer at Ras El-Hekma, Northwestern Coast, Egypt

“…Groundwater flows towards the sea, assuming steady state flow and neglecting the vertical flow rate under the Dupuit-Forchheimer assumption (Dupuit, 1863, Forchheimer, 1901, Naji et al, 1998Mantoglous, 2003;Wenner at al., 2012;Lu et al, 2012;Felisa et al, 2013). This article assumes the hydraulic conductivity (k) is independent of the x, y and z components, which is the case for flow through a single aquifer in an isotropic and homogeneous medium.…”

“…A simplified analytical model was adopted by Felisa et al, 2013 to assess groundwater pumping and examine the impact of seawater intrusion on the vegetation capture zone with excellent representation and computational efficiency. Lu et al, 2016 andZhou (2011), used analytical solutions for seawater-freshwater interface characterizations, to determine the lateral seawater intrusion zone, and to estimate the volume of seawater in coastal aquifers.…”