A logistic regression model for predicting vegetation recruitment into
gravel-bed and sand-bed rivers
Abstract
Vegetation overgrowth in rivers worldwide has been a significant problem
due to its potential to reduce flood-flowing capacity and cause
biodiversity loss. This study tried to develop a model to predict
vegetation recruitment during the initial stage of secondary succession,
leading to vegetation overgrowth. This study chose a logistic regression
model for predicting vegetation recruitment because of its simplicity
and lower computational load than machine learning. The model was
designed for the Kinu River in Japan, undergoing significant vegetation
overgrowth. Data for the model development was obtained from UAV
(unmanned aerial vehicle) aerial surveys and public databases. To ensure
the model’s applicability beyond the training rivers, we trained the
logistic regression model in its performance across different river
flows and geomorphic characteristics, including the normal and flood
times and the gravel-bed and sand-bed. The results indicated that the
logistic regression model with three explanatory variables — the
distance from the river stream, the relative height, and the vegetation
existence history —was optimal for all rivers with the
F-measures of 0.79 to 0.85. Additionally, using UAV imagery
allowed for high spatial resolution in predicting vegetation
recruitment. The best model’s prediction map of the vegetation
recruitment demonstrated that it could accurately predict vegetation
distributions along the main river channel for the gravel and sand beds.