Relative sea-level rise and compound flooding in Mediterranean coastal cities: an evidence synthesis and adaptation framework for Alexandria and Egypt’s Nile Delta
Year: 2026
Type: article
Study design: Systematic Review
Abstract: Coastal cities face increasing climate risks as rising mean and extreme sea levels interact with dense exposure, critical infrastructure, land subsidence, and drainage limitations. This study presents a structured evidence synthesis of coastal urban risk, focusing on Alexandria and Egypt’s Mediterranean coast. Using the IPCC AR6 risk framework and a semi-systematic PRISMA-guided approach, it integrates evidence on relative sea-level rise, extreme sea levels, compound coastal–pluvial flooding, elevation uncertainty, vertical land motion, exposure, and adaptation pathways. The study develops an integrative relative-sea-level and compound-risk adaptation framework linking ocean-driven sea-level rise, local subsidence, terrain uncertainty, compound flooding, and adaptive pathways into a decision-oriented structure. The synthesis shows that coastal risk in Egypt is governed by relative-sea-level rather than oceanic sea-level rise alone, as subsidence can accelerate threshold exceedance and increase flood frequency. For Alexandria, evidence indicates a rising sea-level baseline, increasing extreme high-water-level risks, and vulnerability to compound flooding driven by rainfall, coastal water levels, and drainage constraints. Exposure estimates are highly sensitive to elevation data and vertical land-motion treatment, highlighting the need for high-resolution terrain data and subsidence-aware assessments. The evidence supports context-specific hybrid adaptation portfolios combining selective structural protection, sediment-based and nature-based measures, drainage improvements, and adaptive pathways under uncertainty. The study concludes that climate-resilient coastal planning in Egypt should move beyond static historical assumptions toward relative-sea-level-based, compound-risk-informed, and pathway-oriented adaptation.
Source: Water Science
Authors: Mahmoud Roushdi, Randa Farag
Institution: National Water Research Center
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
Open Access status: diamond
OpenAlex ID: W7213969607