The influence of climate on the flux of sediment to the coastal ocean

A global approach involving data assimilation schemes allows for the prediction of the flux of water and sediment into the coastal ocean, at the dynamic level (daily). The result is either a real-time, or a hindcast or a forecast of coastal hydrology, optimized to estimate sediment loads of rivers. The approach links a compendium of global and regional web-based databases into a GIS system. Because of the explicit link between climate and hydrology, climate is seen to control the flux of sediment. Relational and spatial methods (i.e. RiverTools/sup /spl reg//, HYDRO1k, ArcInfo/sup /spl reg//) facilitate the process of data acquisition useful to sediment discharge models (i.e. HydroTrend). HydroTrend incorporates drainage basin properties (river networks, hypsometry, relief, and lakes) through high-resolution digital elevation models, along with other biophysical parameters (e.g. basin-average temperature, precipitation, canopy, soil depth, hydraulic conductivity, ice fields). Considering that <4% of world-rivers are monitored for their sediment loads, the approach provides a unique means to predict the sediment flux across an entire coastline at a high-resolution temporal scale. Model comparison to long-term observations from the Lanyang River, Taiwan, shows the model can capture average conditions and inter- and intra-annual variability of water discharge, sediment concentration and loads. Application of the schema to the Adriatic coast of Italy shows how the Apennine rivers are strongly influenced by rare floods, capable of generating hyperpycnal flows.