In catchment-based flood management, how do upstream source control measures, such as reforestation, directly affect downstream peak flood flows?

In catchment-based flood management, upstream source control measures like reforestation directly affect downstream peak flood flows by altering the hydrological cycle within the catchment, which is the area of land where all water drains into a common outlet. Reforestation involves planting trees and restoring forest cover in the upper parts of a river basin. These trees and their associated forest ecosystems modify how rainfall interacts with the land, thereby influencing the speed and volume of water reaching downstream river channels. Firstly, tree canopies intercept rainfall, meaning a portion of the precipitation is caught on leaves and branches before it reaches the ground. This intercepted water either evaporates back into the atmosphere or slowly drips to the forest floor, delaying its entry into the soil and drainage system. This process, known as interception storage, reduces the immediate volume of water available for surface ru....