A modified dual-scale scattering model based on the improved integral equation model (I2EM) enables accurate THz channel modeling in a dynamic environment of reflective interactions with water surfaces. The modified model is useful to estimate signal loss and error rates from 120 GHz to 320 GHz in various dynamic aquatic environments with consideration for both macroscopic sinusoidal motion and microscopic surface roughness of the water surface. Model results are compared to laboratory and real world measurements to capture complex temporal and spatial scattering behavior, and the measurements made validate the model improvements.