How Subsurface Water Technologies (SWT) can Provide Robust, Effective, and Cost-Efficient Solutions for Freshwater Management in Coastal Zones

Abstract

Freshwater resources in coastal zones are limited while demands are high, resulting in problems like seasonal water shortage, overexploitation of freshwater aquifers, and seawater intrusion. Three subsurface water technologies (SWT) that can provide robust, effective, and cost-efficient solutions to manage freshwater resources in the subsurface are evaluated using groundwater modelling and validation at field-scale: (1) ASR-coastal to store freshwater surpluses in confined brackish-saline aquifers for recovery in times of demand, (2) the Freshkeeper to counteract salinization of well fields by interception and desalination of upconing brackish groundwater, and (3) the Freshmaker to combine ASR and Freshkeeper to enlarge the volume of natural freshwater lenses for later abstraction. The evaluation indicates that SWT can be used in various hydrogeological settings for various hydrogeological problems like seawater intrusion, upconing, and bubble drift during ASR and have significant economic benefits. Although only sporadically applied to date, we foresee that SWT will stimulate (cost-)efficient and sustainable exploitation of various freshwater sources (like groundwater, rainwater, treated waste water, surface water) in coastal zones. Prolonged SWT testing in the current pilots, replication of SWT in other areas worldwide, and the development of technical and non-technical support tools are required to facilitate potential end-users in investment decision making and SWT implementation.

Quantifying a Sustainable Management Space for Human Use of Coastal Groundwater under Multiple Change Pressures

“…Hydrogeological concepts relating to such aquifer management include an ambiguous safe yield (Llamas and Custodio 2003) as a possible simple rule against overdraft, with the latter defined as groundwater withdrawals exceeding the aquifer recharge, and various other vulnerability indicators (Werner et al 2012). Executing this management task employs then typically advanced flow models, combined with optimisation considering technological options and socio-economics (Koussis et al 2010a(Koussis et al , 2010bStigter et al 2015;Zuurbier et al 2016).…”

Challenges in assessing the regional feasibility of local water storage

“…Based on the literature in Table 1 Based on FWOO application Local context Exploitable volumes differ due to differences in manageability and rechargeability. root zone (Zuurbier, Raat, Paalman, Oosterhof, & Stuyfzand, 2016). Such buffering or shielding capacity confers an added value to some stored water units, compared to water that can be used for irrigation purposes only.…”

Integrated Subsurface Water Solutions for Coastal Wetland Restoration through Integrated Pump&Treat and Aquifer Storage and Recovery (ASR)

“…SWS offers coupled solutions for natural ecosystems with a technological approach in the view of artificial recharge in coastal zones, as many times, the already existing technologies can be inefficient in groundwater problems of coastal aquifers as a result of the existence of brackish and saltwater.SWS involve flexible installations (constructions) and equipment, easily adaptive to the field while they are built on novel designs that are controlled through ICT tools based on improved monitoring and modeling. These solutions have been tested in pilot scale [13] while they are applicable at a range of scales, from agricultural fields to small catchment area or even water well fields of cities.…”