What is the term for the time between rainfall peak and peak discharge?

The term that refers to the time interval between the peak of rainfall and the peak discharge in a river is known as lag time. This concept is crucial in understanding river behavior during and after rainfall events. Lag time is influenced by several factors including the physical characteristics of the river's watershed, soil saturation levels, and the type of rainfall (intensity and duration).

For instance, in urban areas where surfaces are impermeable, lag time might be shorter because water quickly runs off into drainage systems. Conversely, in rural areas with vegetation and porous soils, lag time could be longer as the water gradually seeps into the ground before contributing to the river flow. Understanding lag time helps in predicting flood risks and managing water resources effectively.