Impact of shoreline retreat and inundation due to sea level rise along the coastline adjacent to the Guadiana estuary, Portugal/Spain border

Sampath, DMR

http://hdl.handle.net/10400.1/698

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Dissanayake Mudiyanselage Ruwan Sampath (EM_MSc Thesis -Water and Coastal Management).pdf		7.13 MB	Adobe PDF	Download

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Authors

Sampath, DMR

Advisor(s)

Boski, T.

Abstract(s)

The integrated impact assessment of shoreline retreat and inundation due to sea level rise over the coastal zone of the Guadiana estuary, Portugal/Spain border was carried out to identify and map hazard zones. Geographical Information System tools were used to visualize and analyse impacts on built-up area, transportation network and habitats. The shoreline retreat with the present shoreline evolution rate and the accelerated sea level rise given by three SRES scenarios, namely, B1, A1B and A1FI (upper-bound values: 38, 48 and 59 cm rise in sea level, respectively) exhibit high spatial variability. The adjacent coastline of Monte Gordo tourist beach (Portugal) and the entire shoreline of Ayamonte municipality (Spain) are susceptible to severe erosion. The erosion extent increases gradually with the sea level rise. However, the main forcing of the shoreline retreat is not the climatic change but anthropogenic interventions including construction of coastal defense structures. The first order assessment of shoreline retreat for a hypothetical storm surge with elevated flood contours due to sea level rise shows that the damage to the built-up area and urban habitat can be long lasting while the sandy dune and salt marsh habitats may have resilience depending on sediment supply. The vulnerability of Portuguese side of the Guadiana estuary coastal zone for inundation due to storm surges of 3.0 and 4.9 m from mean sea level (1 and 2 m from the maximum spring high tide level, respectively) shows approximately two-fold and four-fold increase, respectively, relative to the hazard zone marked by the maximum spring high tide (1.9 m from MSL). Two- and three-fold respective increase can be seen in Spain side of the estuary. However, in terms of total area of inundation, Spanish side would severely affect. The main response should be focused on Integrated Coastal Zone Management programme with strategically planned soft engineering interventions to mitigate the negative impacts of shoreline retreat due to sea level rise hazards.