Deltas: Dynamics, Morphology and Observing of delta processes and human impacts
contributed by J. Syvitski
This first lecture reviews the difficulty of defining a delta, reviews concepts of distributary channels and avulsion that are so intrinsically important in deltas, reviews recent progress on modeling an quantifying aggradation in the delta plain, reviews processes in the marine domain and the concept and effect of relative sea level rise
The second lecture discusses morphology of deltas. It reviews the classical ternary division of deltas into fluvial-dominated, wave-dominated and tidal-dominated deltas. But more complex deltas, influenced by a mix of controlling facotrs, are shown and discussed as well. There is special emphasis on deltas during sea level fall and periglacial deltas.:
Deltas have attracted humans from early civilizations onwards. Humans are now increasingly changing the environment and deltas are heavily impacted by humans. This lecture shares examples of human actions affecting deltas: engineering of distributaries and the river channels, groundwater and hydrocarbon extraction causing subsidence, upstream trapping of sediments behind dams, dampening of river discharge peaks and a variety of agricultural practices.
Satellite-based sensors are increasingly used to image delta processes and changes in delta morphology. This fourth lecture highlights the use of NASA's SRTM (Shuttle Radar Topography Mission) data for mapping areas near or below sea level in deltaic regions, the use of MODIS visble bandwidth reflectance data to observe sediment concentrations and flooding, the use of microwave AMSR-E data for water discharge estimates and more.
- Overeem, I., Syvitski, J.P.M., 2009. Dynamics and Vulnerability of Delta Systems. LOICZ Reports and Studies No. 35. Germany.
- Syvitski, J.P.M., Kettner, A.J., Hannon, M. T., Hutton, E.W.H., Overeem, I., Brakenridge, G.R., Day, J., Vörösmarty, C., Saito, Y., Giosan, L., Nicholls, R.J., 2009. Sinking Deltas due to Human Activities. Nature Geoscience 2, 681 - 686.
- Higgins, S. A., Overeem I., Tanaka, A., Syvitski, J.P.M., (2013). Land Subsidence at Aquaculture Facilities in the Yellow River Delta, China. Geophysical Research Letters. 40,15, 898–3902, 16 August 2013.
- Brakenridge, G.R., Syvitski, J.P.M., Overeem, I., Higgins, S. A., Kettner, A.J., Stewart-Moore, J.A., Westerhoff, R., 2013. Global Mapping of Storm Surges and the Assessment of Delta Vulnerability, Natural Hazards. 66:1295-1312.