DEMO Site 8: South Malta Coastal Aquifer, Malta
This pilot-site for the implementation of a seawater intrusion barrier is located in the Southern region of Malta. This location presents the typical hydrogeological characteristics of a coastal 'floating-lens' aquifer system, in direct lateral and vertical contact with seawater. The selection of this site was guided by two further considerations, namely: (i) the groundwater body in this area is considerably degraded, particularly in terms of salinity; and (ii) the site is located close to the main wastewater treatment plant of the island, and thus to a reliable source of treated sewage effluent.
The site is located on the coastal margin of a predominantly agricultural region, which has historically suffered from a shortage of water supply and groundwater degradation due to seawater intrusion. In fact, abstraction of groundwater for human consumption from this region has long been discontinued due to the degrading quality of the resource. The creation of a seawater intrusion barrier is considered to be an effective method to reduce the outward flow of freshwater and thus increase the availability of groundwater in the region. Moreover, the influx of higher quality water from the central regions of the aquifer system will also ensure an improvement in the regional quality of the groundwater body.
The Malta South demonstration project will involve the use of a line of coastal boreholes through which treated sewage effluents (which actually is of a better quality than the groundwater in the coastal fringe of the aquifer) will be directly discharged to the saturated zone. It is envisaged that the production of treated wastewater at the Malta South wastewater treatment plant will exceed the demand of the agricultural sector in the region, making it available for aquifer management purposes. The quality of the recharging water will be ensured through the treatment regime (tertiary treatment and/or further polishing) applied in the wastewater treatment plant.
The demonstration project will start with the Malta Resources Authority (MRA) developing a regional numerical model of the sea-level groundwater system to assess the potential impact of the sea-level aquifer system. This model will be developed using the Visual-MODFLOW groundwater modelling package. This exercise will enable the MRA to assess different scenarios in order to develop an optimum design of the artificial recharge system. A treated effluent quality management and monitoring system will also be developed by the MRA (with the support of WSC), wherein the necessary checks will be undertaken (regularly) to ensure that the quality of the effluent used for artificial recharge does not result in the qualitative degradation of the sea-level aquifer system.
The demonstration project will moreover involve the development of a continuous monitoring system which will assess the quantitative and qualitative impact of the pilot project on the regional status of the sea-level aquifer system. This monitoring system will be based on a network of multi-parametric groundwater monitoring probes installed in monitoring wells located downstream and upstream of the artificial recharge boreholes. The location of these monitoring points will be such as to enable the MRA to assess the local and regional impact of the artificial recharge pilot project. It is moreover noted that such monitoring strategies, particularly on a regional basis, need to focus on the medium to long-term scenarios, mainly due to the slow response times of the islands' sea-level aquifer systems.
The main deliverable will be the demonstration of an artificial recharge scheme which envisages the utilization of treated sewage effluents for the management of coastal groundwater bodies to combat seawater intrusion. The application of such seawater barriers will not only improve the status of the aquifer systems, but also increase the yield potential of these freshwater bodies.
The main applicability of this scheme arises from two main facts: (i) the implementation of the EU's Waste Water Treatment Directive has seen the increased availability of treated sewage effluents in coastal regions, which are currently being discharged into the sea; and (ii) increasing water demand has increased the stress on coastal groundwater resources resulting in the degradation of these aquifer systems, including the seawater intrusion phenomenon which is a major threat to coastal aquifers in many regions of the Mediterranean. Current climate change scenarios indicate that water demand will increase in the future, further exacerbating the problem.
MARSOL
Demonstrating Managed
Aquifer Recharge as a
Solution to Water Scarcity
and Drought
An EU FP7 Project
Coordination & Contact:
Prof. Dr. Christoph Schüth
Darmstadt Technical University
Institute of Applied Geosciences
Schnittspahnstr. 9
64287 Darmstadt
Germany
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The MARSOL project receives funding from the European Union's Seventh Framework Programme for Research, Technological Development and Demonstration under grant agreement no 619120. This project website reflects only the authors' views and the European Union is not liable for any use that may be made of the information contained therein. |