Desertification status mapping in Muttuma Watershed by using Random Forest Model

Potential of the Random Forest Model on mapping of different desertification processes was studied in Muttuma watershed of mid-Murrumbidgee river region of New South Wales, Australia. Desertification vulnerability index was developed using climate, terrain, vegetation, soil and land quality indices to identify environmentally sensitive areas for desertification. Random Forest Model (RFM) was used to predict the different desertification processes such as soil erosion, salinization and waterlogging in the watershed and the information needed to train classification algorithms was obtained from satellite imagery interpretation and ground truth data. Climatic factors (evaporation, rainfall, temperature), terrain factors (aspect, slope, slope length, steepness, and wetness index), soil properties (pH, organic carbon, clay and sand content) and vulnerability indices were used as an explanatory variable. Classification accuracy and kappa index were calculated for training and testing datasets. We recorded an overall accuracy rate of 87.7% and 72.1% for training and testing sites, respectively. We found larger discrepancies between overall accuracy rate and kappa index for testing datasets (72.2% and 27.5%, respectively) suggesting that all the classes are not predicted well. The prediction of soil erosion and no desertification process was good and poor for salinization and water-logging process. Overall, the results observed give a new idea of using the knowledge of desertification process in training areas that can be used to predict the desertification processes at unvisited areas.

Automated summary

This study examines the potential of the Random Forest Model in mapping different desertification processes. The desertification vulnerability index was developed using various indices and factors, allowing for the identification of environmentally sensitive areas. The overall accuracy rate for predicting different desertification processes varied, with soil erosion and no desertification processes showing good prediction, while salinization and waterlogging processes showed poor prediction.