Geomorphological evolution of the Umm al-Quwain (UAE) coastal-lagoon system: Natural processes and recent human impact

Coastal lagoon systems are highly sensitive environments currently experiencing the impact of climate change and human pressure, which are triggering alteration of pristine biodiversity and geomorphic dynamics. Climateand/or tectonic-induced changes in sea-level and shifts in the base level and/or flow rate of rivers connected to inlets heavily affect the balance of lagoon ecosystems, triggering ecological changes and/or alterations in landforms. For instance, the shorelines of the Arabian Peninsula, stretching from the Red Sea to the Persian/ Arabian Gulf, are dotted by coastal lagoons that are undergoing deep transformations. Across the Holocene, Arabian lagoons underwent subsequent phases of modification triggered by sea-level changes, modifications of ocean circulation, and post-Last Glacial Maximum shifts in the discharge of main rivers (e.g., Tigris and Euphrates rivers). These factors reshaped the geomorphology of such contexts, promoting the evolution of freshwater ecosystems along the shorelines of the United Arab Emirates (UAE) and influencing the growth of extensive mangrove forests. In recent years, human agency has disrupted the pristine dynamics and ecosystems of coastal-lagoon systems between Abu Dhabi and Ras al-Khaimah. Local lagoons have undergone significant changes due to urban expansion involving land reclamation initiatives along the coast to expand coastal areas, including the construction of artificial islands and the consequent changes in circulation and reduction of mangrove forests. The lagoon of the Emirate of Umm al-Quwain (UAQ), thanks to the slower rate of urban sprawl and limited land reclamation operations, still preserves an extensive mangrove ecosystem, pristine landforms, and almost unspoilt tidal dynamics. For that reason, it constitutes the ideal context for a geomorphological assessment based on a combined multi-temporal remote sensing (from 1968 to 2022) and field validation approach, aimed at achieving a deep understanding of the formation and dynamics of tidal-lagoon and coastal systems and landforms. Furthermore, a detailed geomorphological reconstruction of specific sectors of the UAQ lagoon traced its evolutionary history, informing interpretations of past human communities’ adaptation strategies and resource exploitation patterns.