ADAPTATION TO SALTWATER INTRUSION ALONG HIGHLY URBANIZED COASTAL AREAS: A DSS-BASED SOCIOECONOMIC PERSPECTIVE

Abstract

Saltwater intrusion (SWI) is a global coastal problem caused by aquifer over-pumping, land-use change, and potential climate change impacts. SWI is a threat to coastal aquifers worldwide by rendering groundwater quality not viable for its intended use. Understanding SWI and its impact is indispensable for informed decision-making on aquifer management. Despite advances in SWI research, it remains challenging to detect, quantify and manage. Given the complex pathways that lead to SWI, coastal urban areas with poorly monitored aquifers are in need of simple, robust, and probabilistic decision support models that can assist in better understanding and predicting SWI, while also exploring effective means for sustainable aquifer management.

This research targets the Eastern Mediterranean, an area highly vulnerable to increased saltwater intrusion into coastal fresh water aquifers. It examines the main drivers of SWI, assessing the relative impacts of local anthropogenic activities and projected global climate change. The research appraises the spatial and temporal dynamics of SWI and evaluates the associated socio-economic burden related to the degradation of groundwater resources used for domestic purposes. It attempts to estimate the risk of SWI through constructing the interplay of natural, anthropogenic and climatic drivers in view of adaptation and mitigation potentials as well as socio-economic and political conditions. This research further develops a Bayesian Belief Network (BBN) to account for the complex physical and geo-chemical processes leading to SWI while linking the severity of the SWI to the associated socioeconomic impacts. The BBN is further expanded into a dynamic Bayesian network (DBN), to assess the temporal progression of SWI and to accurately compound uncertainties over time. Pilot demonstrations mainly targeted a highly urbanized metropolitan as well as a densely populated city, a suburb and an agricultural area.

Results exhibited indications of advanced SWI in the pilot areas, albeit with spatial and temporal heterogeneity. Results also showed that the future impacts of climate change were largely secondary as compared to the persistent water deficits hinting towards the importance of demand management. Results highlighted the socioeconomic burden associated with the different scenarios including costs and benefits of adaptation strategies. It shows that while supply and demand management can pause the progression of salinity in the aquifer, the potential for reducing or reversing salinity is not apparent.

Through building a robust representation of drivers and impacts of SWI and the socioeconomic implications and policy options, the constructed DBN acts as an effective decision support tool to aid coastal managers towards sustainable aquifer management. While the research results provided valuable outcomes for the Eastern Mediterranean region, it equally conveyed to the global community lessons learnt on saltwater intrusion drivers, dynamics, implications and adaptation potential as well as a modular DBN-based decision support tool easily transferable to other aquifers.