Process learning of stream temperature modelling using deep learning and
big data
Abstract
Stream water temperature is considered a “master variable” in
environmental processes and human activities. Existing process-based
models have difficulties with defining true equation parameters, and
sometimes simplifications like assuming constant values influence the
accuracy of results. Machine learning models are a highly successful
tool for simulating stream temperature, but it is challenging to learn
about processes and dynamics from their success. Here we integrate
process-based modeling (SNTEMP model) and machine learning by building
on a recently developed framework for parameter learning. With this
framework, we used a deep neural network to map raw information (like
catchment attributes and meteorological forcings) to parameters, and
then inspected and fed the results into SNTEMP equations which we
implemented in a deep learning platform. We trained the deep neural
network across many basins in the conterminous United States in order to
maximize the capturing of physical relationships and avoid overfitting.
The presented framework has the ability of providing dynamic parameters
based on the response of basins to meteorological conditions. The goal
of this framework is to minimize the differences between stream
temperature observations and SNTEMP outputs in the new platform.
Parameter learning allows us to learn model parameters on large scales,
providing benefits in efficiency, performance, and generalizability
through applying global constraints. This method has also been shown to
provide more physically-sensible parameters due to applying a global
constraint. This model improves our understanding of how to parameterize
the physical processes related to water temperature.