Human development drives global estuary and delta loss

초록

Economy and population growth along coastal environments are rapidly increasing, and threatenestuarine and deltaic systems. Recent anthropogenic alterations have led to changes in sediment supply,so that estuaries and deltas in sediment depleted areas remain vulnerable to marine processes. Here, wecompared the 20 century extent of estuaries and deltas to modern aerial images throughout the worldto identify long-term and short-term drivers of estuarine change, and how they vary with coastaldevelopment. We identified the extent and shape (change in width throughout the estuary) of more than4,000 estuaries and deltas worldwide, and compared to local dam construction and land use practices todetermine main drivers of estuarine change. Preliminary results suggest that global estuaries and deltashave decreased by more than 5,000 km within the last 30 years, where areal loss is influenced primarilyby local farming activity and dam occurrence. Therefore, estuaries tend to contract following daminstallment and where agriculture practices are high. Interestingly, post-industrial estuarine change (early1900s ? 1975) may greatly exceed modern change (1984 ? 2015). These observations suggest thatestuaries and deltas respond quickly to anthropogenic alterations, and the possibility that further humanchanges may lead to long-term loss of major coastal environments.