Embodiments relate to estimating river discharge and depth. Initially, observed velocities are used to generate a maximum velocity streamline for a river section, which is then used with an observed shoreline to construct a streamline curvilinear grid. The grid is used to interpolate scattered velocity data points, which are used with a bottom friction of the river section to approximate mean total head slope values. A least squares minimization scheme is applied to a velocity-slope relationship to estimate a bottom friction and discharge coefficient by fitting a difference in the predicted mean total head elevation values between upstream and downstream ends of the river section to a respective ζ-average of the measured total head values of the river section. Discharge of the river section is determined based on the coefficient and a velocity-depth relationship and then used to generate a river forecast.