Inverse Analysis of Experimental Scale Turbidity Currents by Deep
Learning Neural Network
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 novel method for the inverse
analysis of turbidity current using deep learning neural network (DNN)
was proposed. This study aims to verify this method using artificial and
flume experiment datasets. Development of inverse model by DNN involves
two steps. First, artificial datasets of turbidites are produced using a
forward model based on shallow water equation. To develop a inverse
model, DNN then explores the functional relationship between initial
flow conditions and characteristics of the turbidite deposit through the
processing of artificial datasets. The developed inverse model was
applied to 200 sets of artificial test data and four sets of experiment
data. Results of inverse analysis of artificial test data indicated that
the flow conditions can be precisely reconstructed from depositional
characteristics of turbidites. For experimental turbidites, spatial
distributions of grain size and thickness were accurately reconstructed.
With regard to hydraulic conditions, reconstructed values of flow
heights, sediment concentrations, and flow durations were close to the
measured values. In contrast to the other values, there was a larger
discrepancy between the measured and reconstructed values of flow
velocity, which may be attributed to inaccuracies in sediment
entrainment functions employed in the forward model.