1D Hydraulic Modeling w/ LiDAR Data Noah J. Finnegan 1 1 UC Santa Cruz, Earth & Planetary Sciences

Workshop Goal: Extract hydraulic geometry from a LiDAR DEM Import this into HecRAS Perform a 1D flow calculation for an arbitrary discharge or discharges Take variables computed in HecRAS (for instance, flooded area, mean shear stress, mean velocity) and bring these back into the GIS environment.

Motivation Using river bed slope to estimate, for example, spatial patterns in rates of river incision or sediment transport implicitly assumes uniform flow, i.e. spatial accelerations in the flow are not allowed.

Motivation Using river bed slope to estimate, for example, spatial patterns in rates of river incision or sediment transport implicitly assume uniform flow, i.e. spatial accelerations in the flow are not allowed.

Motivation Using river bed slope to estimate, for example, spatial patterns in rates of river incision or sediment transport implicitly assume uniform flow, i.e. spatial accelerations in the flow are not allowed.

For some problems, the local variation is the problem

Motivation Using river bed slope to estimate, for example, spatial patterns in rates of river incision or sediment transport implicitly assume uniform flow, i.e. spatial accelerations in the flow are not allowed.

Motivation Using river bed slope to estimate, for example, spatial patterns in rates of river incision or sediment transport implicitly assume uniform flow, i.e. spatial accelerations in the flow are not allowed.

Background

Mass Conservation

Manning’s Equation

Mass Conservation Manning’s Equation

Mass Conservation Manning’s Equation

Depth to centroid of area

L = Reach length S o = Bed Slope sin  tan  S 

Depth to centroid of area L = Reach length S o = Bed Slope sin  tan  S 

Depth to centroid of area L = Reach length S o = Bed Slope sin  tan  S 