Subject
- #Mangrove forests
- #Coastal geomorphology
- #Natural barriers
- #Coastal flooding
- #Coral reefs
What coastal geomorphology controlled flooding in Mauritius
Flooding in Mauritius is significantly controlled and shaped by its coastal geomorphology—primarily via coral reefs, mangroves, beach profiles, and human modifications.
Key Coastal Geomorphological Features
Coral Reefs: Fringing and barrier reefs surround much of Mauritius and serve as the primary natural barrier, absorbing wave energy from the open ocean, decreasing the power of storm surges, and thus reducing erosion and inland flooding. Degradation of these reefs (via bleaching, sedimentation, and pollution) has been directly linked to increased coastal flooding and higher vulnerability to intense storms.
Mangrove Forests: Mangrove ecosystems grow along the shoreline, especially in lagoons and estuarine zones. Their dense roots stabilize sediment, buffer against wave action, reduce coastal erosion, and trap runoff, protecting inland areas from flash floods and sea encroachment. Restoration programs have been expanding mangrove cover to boost resilience.
Seagrass Beds: Seagrass meadows, often interconnected with mangroves and reefs, help trap sediments and reduce water turbidity, further supporting reef health and providing a secondary barrier to coastal flooding.
Beach Profiles and Lagoons: Wide, gently sloping sandy beaches backed by shallow lagoons can further dissipate wave energy before it reaches human settlements. Where these features are absent or eroded (e.g., via sand mining or unregulated development), flooding risk rises sharply.
Seawalls and Artificial Structures: In regions lacking natural reef or mangrove barriers (such as Riviere des Galets), seawalls and other engineered defenses are used to curb flooding and erosion, though sometimes these structures fail under extreme conditions or increase wave overtopping and downstream erosion if poorly maintained.
Impacts of Geomorphology on Flooding
Where coral reefs and mangroves are healthy and extensive, flooding is significantly attenuated, and wave-driven inundation rarely penetrates far inland, even during strong cyclones.
Areas with degraded natural barriers or replaced by hard structures experience higher rates and severity of coastal flooding and erosion, as natural wave dissipation is lost.
Urban runoff, rapid catchment development, and reduction of vegetated buffer zones in the watershed increase the speed and volume of water entering coastal areas during heavy rains, worsening flooding when combined with high tides or surges.
In summary, coral reefs and mangroves are the most important natural geomorphic features for controlling coastal flooding in Mauritius, supplemented by sandy beaches and lagoons, while human interventions become critical where natural protections are lost or insufficient.
