Post on 12-Jan-2016
Why bother?• Landscape evolution
• Channel morphology
• Channel stability assessment and stable channel design
• Bank erosion
• Fine sediment sources
• Benthic habitat & disturbance regime defined by bed-material flux
• Testing land use practices
Scales • Temporal
– Storm (rising/falling limbs) – Seasonal – Decadal
• Spatial – Slope – Small basin – Large basin
Main Objectives1. Examine the magnitude and frequency of sediment
mobilization events and relate them to the hydrological magnitude and frequency of floods. This will be achieved by calculating event sediment yield, which will be related to sediment supply (storage) and hydrograph characteristics.
Main Objectives2. Quantify hysteresis in sediment mobilization related to
sediment supply and hydrograph characteristics.
Idealized set-line trend for one season
Time
First F
lood
Last
Flood Rising
Falling
Log Discharge
Log
Con
cen
trat
ion
Main Objectives3. Assess changes in runoff, stream flow, and sediment
duration curves related to changes in land use and climate.
Bed Composition
Low Flows vs. High Flows
In-channel supply Entrainment and transport
Stronger influence of bed compositionOnly available fines entrained
Coarse particles mobilizedFines released
Main Objectives5. Establish regional scaling relations for the variation of
sediment yield with drainage basin area.
6. Examine the spatial and temporal variation in sediment yield using the regional sediment yield relations for the landscape. This is essentially a matter of scaling, and will require us to evaluate the extent to which it is possible to transfer findings from one scale of investigation to another.
Main Objectives7. Modeling sediment yield (fine sediment) using Lu et al.
(2005) model. Relate objective 6 to 3 and link to other groups.
Other objectives 1. How is the land use likely to influence the basin hydrology and
the spatial and temporal sediment yield variations at the landscape scale.
2. The response of the landscape to land use and soil conservation practices (has been studied for small basins but not at the landscape scale). It has been established that the response of a catchment system will vary, subject to previous disturbance conditioning effects and that the relaxation of a system is conditioned by previous disturbance.
3. How the landscape is likely to response to climate change and other disturbances.
4. Connectivity of the landscape from the plot scale to the drainage basin scale. For efficient transport of sediment, the hydrological and geomorphological connectivity of the landscape is poorly understood yet remains an open question.