Future Earth Coasts: The Mississippi and Yangtze Rivers as Examples

Christopher D'Elia, Louisiana State University, School of the Coast and Environment, Baton Rouge, LA, United States, Kehui Xu, Louisiana State University, Department of Oceanography and Coastal Sciences, Baton Rouge, LA, United States, Zhongyuan Chen, East China Normal University, State Key Laboratory of Estuarine and Coastal Research, Shanghai, China, John Day, LSU, School of the Coast and Environment, Baton Rouge, LA, UNITED STATES and Martin Le Tissier, Future Earth Coasts, IMERC Office, National Maritime College of Ireland, Ringaskiddy, Co. Cork, Ireland
Abstract:
Deltas and estuaries are productive and fertile links between the land and the sea. Deltas occupy only about 5% of the Earth’s surface but sustain over a half billion people all around the world. Many river deltas are endangered because of extensive dam and levee construction, declining sediment supply, groundwater withdrawal, relative sea level rise and severe coastal erosion, leading to a variety of threats to natural, economic and social systems. About 630 million people now live at an elevation of 10 m or less above mean sea level, and maintaining sustainable land with a rising sea will be a challenging problem for many major deltaic coasts and cities in the next century. Stemming from 20 years of LOICZ (Land-Ocean Interactions in the Coastal Zone), Future Earth Coasts is a new global initiative that seeks to enable the scientific and social scientific communities to build knowledge through collaborative processes to better understand and address the profound and urgent changes occurring in vulnerable coastal zones. The topics of this comparative study are the Mississippi and Yangtze (Changjiang) Rivers, the largest in the United States and China, respectively. We use these two rivers as examples to evaluate current conditions and catalyze future discussion. The Mississippi and Yangtze both have had long-term observations of physical and biological processes that affect human activities, making it possible to quantify both natural and anthropogenic impacts. We also consider the limits to concept of sustainability for the Earth’s biosphere and human civilization, and emphasize biophysical constraints and demographic challenges.