The objective of this study was to map the erosions that are occurring on the banks of Ribeirão São João in Porto Nacional - TO, these erosive processes come from the detachment and transportation of the soil particles, which can be deposited in the watercourse of the stream, causing the increase of the load in the streambed. Two erosions were the biggest. Soil characterization tests were done in each erosion. Monitoring its progress was made by pins erosion method, which was installed on... Topic: Erosion. Erosion pins. Ribeirão São João.