How is travel time (Tt) defined in a watershed?

Travel time (Tt) in a watershed specifically refers to the duration taken by runoff to move from one point to another within the watershed. This concept is crucial in hydrology and stormwater management because understanding Tt helps predict how quickly water will flow through a landscape, influencing flood predictions and the timing of water quality impacts downstream. Factors such as topography, land use, and soil characteristics all contribute to the variability in Tt, which can affect the management of stormwater runoff and erosion control strategies.

The other options address different processes related to water movement or precipitation but do not define travel time in the context of watershed dynamics. For instance, evaporation and infiltration are separate hydrological processes that involve the movement of water in different forms, while the time for rainfall to reach the ground pertains to precipitation rather than water flow across the landscape. Thus, the focus on runoff movement between two points accurately captures the essence of travel time in a watershed context.