Special Session hosted by the IAG and IGU Commission on Land Degradation and Desertification during 29th. International Geographical Congress, Seul, South Korea, August 16, 2000

Date: 7 November 2000

The Session was entitled Sediment Budgets in Geomorphic Systems and was organised by Maria Sala and Olav Slaymaker. There were five research paper presentations as follows:

1. Olav Slaymaker (Canada) - Implications of sediment budgetting studies for land management.
2. Roman Batalla and Maria Sala (Spain) - Sediment yields in streams of the Catalan Coastal Ranges and Pyrenees.
3. Julie Throne and Arthur Conacher (Australia) - Estimation of sediment yields from small agricultural catchments in south-western Australia.
4. Norbert P. Psuty (U.S.A.) - Coastal foredune evolution as part of a spatial/temporal sediment budget continuum.
5. Moshe Inbar (Israel) - A sediment budget of coarse bedload in the upper Jordan River.

Batalla and Sala, on the basis of sediment yields from 22 selected streams draining areas from 10 to 10,000 ha., demonstrated a curvilinear relation between specific sediment yield and basin area, with a maximum recorded at an intermediate basin area. They noted the parallel trend discovered by Church and Slaymaker (1989) and speculated that in the Spanish data it was the intensity of late glacial periglacial processes that had generated exceptional sediment availability and that this slug of sediment is still making its way to the ocean.

Throne and Conacher used data on sediment accumulation from 24 hillslope catchments to estimate rates of soil loss. Inbar continued his analysis of boulder transport in the upperJordan River and concluded that catastrophic floods are the effective modifiers of fluvial landforms.

Psuty calculated annual sediment budgets for a series of coastal sections at Sandy Hook, New Jersey and was thereby able to plot the shifting locus of maximum sediment loss over time. The influence of beach nourishment sources could also be plotted over time.

Slaymaker discussed the land management implications of sediment budgetting and illustrated with reference to various scales of analysis in North America.

Although the number of contributions to this session was disappointingly small, the presentations were coherent and had the following common denominators:

1. The importance of scale effects in sediment budgetting
2. The value of quantitative sediment budgets
3. The applied significance of sediment yield and budget studies and
4. The flexibility of the sediment budget approach as applied to suspended sediment transport, bedload transport and coastal longshore processes.