Updated May 23, 2008.  

Topography: Form and Process
Rivers grind their way into bedrock, branching out into the emergent landscape.  Steeper valleys appear to be cut by periodic debris flows while lower gradient valleys are cut by the wear of bedload. Epidicity in incision and propagation of knickpoints lead to terrace formation. 

The river channels have a hierarchical structure that runs from small to large, steep to low gradient, debris flow to fluvial cut. This structure leads to distinctive river profiles, process dominance change and scaling relations that become the physical template for ecological processes.

High-resolution digital topography provides the common template for Desktop Watersheds (DW) research into the physical template. The topography is derived from light detection and ranging (LIDAR) at 1 meter square resolution. From the digital elevation maps we extract topographic features, from watershed boundaries to channel edges. We use digital-terrain based models to guide prioritization of research and maintain a tight coupling between modeling, observation, and experimentation.

Areas Under Investigation
1.  Numerical techniques for feature extraction from LIDAR.

2.  Topographic signatures of properties and processes.

3.  Controls on rate of landslide transport to channels.

4.  Sediment routing; coarse sediment transport in shallow flow; fine sediment interaction with coarse bed.

5.  Predictive models for channel incision.

Current Research
This year saw the LIDAR derived topographic data that was acquired in Year 5 for the South Fork Eel River watershed permeate many research projects. Using this data, we introduced a new approach for mapping valleys and channels based on wavelet and curvature analysis of their topographic signature rather than an assumption of some critical drainage area or slope. The high resolution topographic data now enables us to explore other scaling relationships useful for characterizing the spatial structure of networks and topography, with application to water and sediment routing, as well as ecosystems dynamics.

One NCED collaboration is exploring and discovering the links between hillslope hydrology, vegetation, atmospheric conditions and climate change through intensive monitoring of a hillslope along Elder Creek in the Angelo Coast Range Reserve (ACRR). A unique focus is the attempt to document the role of "rock moisture" in providing critical dry season water to trees, a virtually unexplored problem. This work will form the foundation for the development of a dynamic hydrologic model in DW.

Together these discoveries are expanding the foundation of terrain-based (map-based) prediction of the spatial patterns and dynamics of ecosystems and the physical processes that drive them. We are conducting studies on the cascade of processes that drive landscape evolution and directly or indirectly affect ecosystems. These multiyear studies have recently revealed:

1.  The role of coarse sediment in the debris flow wear of bedrock.

2.  The importance of the spatial heterogeneity of material properties in sediment production and transport.

3.  The spatial and temporal variability in rates of landsliding and channel incision in the ACCR associated with climate variation and knickpoint propagation.

4. The high transport rate of gravel through steep boulder reaches but the surprising tendency for sediment to be less mobile on steep slopes.

5.  The predictability of the trapping of sand transported across gravel at low flow (thus directly influencing habitat conditions).