Experimental Verification of Inverse Analysis of Turbidity Currents from
Their Deposits by Machine Learning Technique
Abstract
Despite the importance of turbidity currents in environmental and
resource geology, their flow conditions and mechanism are not well
understood. To resolve this issue, a new method for the inverse analysis
of turbidity current using deep learning neural network (DNN) was
proposed. This research aims at verifying and calibrating this method
using artificial and flume experiment datasets. The forward model based
on the shallow water equation was employed in this study to produce
artificial datasets of turbidite deposits. DNN was applied to two
hundred artificial datasets and two sets of experiment data. As a result
of inversion by DNN, spatial distributions of grain size and thickness
of experimental turbidites were reconstructed accurately. With regard to
hydraulic conditions, the flow heights were reasonably estimated, and
sediment concentrations reconstructed were reasonable except for regions
where the values measured in experiments were extremely low. Flow
duration also showed reasonable reconstructed values. In contrast to the
other values, there was a large discrepancy between the measured and
reconstructed values of flow velocity. The reason for this discrepancy
in velocity may be attributed to inaccuracy in closure functions
employed in the forward model. Future application to actual data of
natural scale turbidite is anticipated.