Optimized convolutional neural network - kernel ridge regression-error correction method: an advanced model for...

Predicting soil saturated hydraulic conductivity (Ks) is essential for understanding water movement in soils and designing efficient irrigation and drainage systems. Thus, our paper proposes the mutated grasshopper optimization (MGRO) algorithm- convolutional neural network (CNN)- kernel ridge regression (KRR)-error correction (ERC) method to predict K_s. The MGRO-CNN-KRR-ERC (MCKE) model is executed in several steps. First, the MGRO algorithm optimizes the hyperparameters of the CNN and KRR techniques. Then, the CNN technique is trained on the input data to produce a set of outputs called the summary vector, which represents the compact and meaningful descriptor of the original dataset for subsequent KRR processing. Next, the summary vector is fed into KRR to produce predicted K_s data. Finally, the ERC method reduces the difference between these data and measured Ks values to improve the overall prediction accuracy. The model uses four soil properties as input data. Our study uses the mutual information index to select the most informative features, and the results indicate that all four properties significantly affect the precision of predictions. The current research also utilizes the kernel estimation method to determine the uncertainty of the predicted Ks values. The study results demonstrate that the MCKE model significantly outperforms KRR, CNN, and hybrid approaches in terms of predictive accuracy, error reduction, and robustness. Specifically, the MCKE model achieves a reduction of 51-93% in mean absolute percentage error (MAPE to all other predictive models. In general, the MCKE model provides a robust and reliable framework for predicting Ks under diverse environmental conditions.