Automatic measurement and computation of stream cross-sectional area using ground penetrating radar with an adaptive filter and empirical mode decomposition

•An integral and non-contact method for cross-sectional area measurement.•A method composed of GPR, an adaptive filter and empirical mode decomposition.•GPR without contacting the water is used to measure the water area accurately and promptly.•Adaptive filter for auto-correction to reduce difficulties in data interpretation.•Potentially be used during a flood event for erosion and deposition processes.