Runoff is the portion of precipitation, snowmelt, or other forms of water that flows over the land surface and through streams, rivers, and channels toward lakes, reservoirs, or oceans after satisfying losses due to interception, infiltration, evaporation, transpiration, and surface storage. It is one of the most important components of the hydrological cycle because it determines the availability of water resources, influences flood occurrence, supports irrigation and hydropower generation, and helps in planning hydraulic structures. Runoff may occur as surface runoff, subsurface runoff, and base flow depending on the path taken by water before reaching a stream. Measurement of runoff is essential for water resources planning, flood forecasting, reservoir design, watershed management, and hydrological studies. The methods used for measuring runoff are broadly classified into direct and indirect methods. Direct methods involve actual measurement of streamflow or runoff volume. The stream gauging method is the most common direct method. In this method, the discharge of a river or stream is measured at a gauging station. Water level or stage is continuously recorded using staff gauges, float gauges, or automatic water level recorders. A stage-discharge relationship, known as a rating curve, is developed from repeated discharge measurements. Once the rating curve is established, continuous runoff can be estimated from recorded water levels. The velocity-area method is another important direct method. The cross-sectional area of the stream is measured, and the average velocity of flow is determined using current meters or Acoustic Doppler Current Profilers (ADCP). Runoff or discharge is calculated using the equation Q = A × V, where Q is discharge, A is the cross-sectional area, and V is