Artificial neural networks (ANNs) are powerful tools to discover correlations in The regression results for training, validation, test and all datasets are shown in Fig. , in which the R-value is the coefficient of correlation representing how well the ANN prediction matches the real water content. R is 1 for a perfect fit, where all the data fall on a 45° line, while 0 means no correlation. R for the training data has been found to be around 0.917, indicating an excellent correlation. Although not all points fall on the 45° line, the generalisation performance is guaranteed as no overfitting happened.