Sea-level rise impacts on seawater intrusion in coastal aquifers: Review and integration

Climate change, sea level rise, over-pumping and saltwater intrusion present some of the future challenges of water resources management in coastal areas. Over-abstraction is considered one of the main causes of seawater intrusion and the rise in sea levels accelerates the intrusion. With the combined impact of sea level rise and over-pumping the problem becomes exacerbated and requires urgent solutions. Previous studies have mainly focused on the study of impact of sea level rise or over-abstraction on seawater intrusion separately and their combined effects have not been studied in the literature. This paper presents application of a coupled transient density-dependent finite element model to simulate seawater intrusion in coastal aquifers and investigates the individual and combined effects of likely sea level rise and over-pumping on seawater intrusion. Three scenarios are considered: rise in sea levels due to climate change, decline in groundwater table due to over-pumping and combination of sea level rise and over-pumping. The results show that, in the case study considered in this paper, the rise in the sea level moved the transition zone inland by about 5%. However, the combination of sea level rise and over-pumping resulted in further inland movement of the transition zone (about 8%). The amount of intrusion greatly depends on the depth, size and properties of the aquifer. While the intrusion is a few metres in a small aquifer, it could be several kilometres in a large aquifer.

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GIS analysis of effects of future Baltic sea level rise on the island of Gotland, Sweden

Natural Hazards and Earth System Science ◽

10.5194/nhess-16-1571-2016 ◽

2016 ◽

Vol 16 (7) ◽

pp. 1571-1582 ◽

Cited By ~ 3

Author(s):

Karin Ebert ◽

Karin Ekstedt ◽

Jerker Jarsjö

Keyword(s):

Baltic Sea ◽

Sea Level Rise ◽

Sea Level ◽

Seawater Intrusion ◽

Coastal Aquifers ◽

Saltwater Intrusion ◽

Developed Countries ◽

Global Perspective ◽

The Baltic Sea ◽

The Baltic

Abstract. Future sea level rise as a consequence of global warming will affect the world's coastal regions. Even though the pace of sea level rise is not clear, the consequences will be severe and global. Commonly the effects of future sea level rise are investigated for relatively vulnerable development countries; however, a whole range of varying regions needs to be considered in order to improve the understanding of global consequences. In this paper we investigate consequences of future sea level rise along the coast of the Baltic Sea island of Gotland, Sweden, with the aim to fill knowledge gaps regarding comparatively well-suited areas in developed countries. We study both the quantity of the loss of features of infrastructure, cultural, and natural value in the case of a 2 m sea level rise of the Baltic Sea and the effects of climate change on seawater intrusion in coastal aquifers, which indirectly cause saltwater intrusion in wells. We conduct a multi-criteria risk analysis by using lidar data on land elevation and GIS-vulnerability mapping, which gives the application of distance and elevation parameters formerly unimaginable precision. We find that in case of a 2 m sea level rise, 3 % of the land area of Gotland, corresponding to 99 km2, will be inundated. The features most strongly affected are items of touristic or nature value, including camping places, shore meadows, sea stack areas, and endangered plants and species habitats. In total, 231 out of 7354 wells will be directly inundated, and the number of wells in the high-risk zone for saltwater intrusion in wells will increase considerably. Some valuable features will be irreversibly lost due to, for example, inundation of sea stacks and the passing of tipping points for seawater intrusion into coastal aquifers; others might simply be moved further inland, but this requires considerable economic means and prioritization. With nature tourism being one of the main income sources of Gotland, monitoring and planning are required to meet the changes. Seeing Gotland in a global perspective, this island shows that holistic multi-feature studies of future consequences of sea level rise are required to identify overall consequences for individual regions.

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