Headwater catchments are the source areas of rivers and streams and are critical for maintaining the structure, function, productivity and complexity of downstream ecosystems. They are vital to hydrologic cycle as they are one of the main areas where precipitation contributes to surface and groundwater. Headwaters are typically less intensively used than downstream areas.
Many headwater areas are dominated by extensive agriculture, forests or other semi-natural land cover types predominate. Forests in headwater areas play a beneficial role for water quantity and quality. Establishing or maintaining forest cover in headwater catchments is a widely used practice in many major cities worldwide including New York, Istanbul and Singapore, as these cities rely on headwater forests for drinking water provisioning. Forest soils generally have better infiltration capacity than other land cover types and may act as a “sponge”, slowly releasing rainfall. They also stabilise slopes in steep regions, reducing the risk of landslides.
However, afforestation of headwaters in arid areas can reduce water yields and requires careful consideration of tree species and strategies.
Maintaining and restoring forests in headwater areas provides multiple benefits, such as improved soil water retention, pollution interception, erosion control and enhanced biodiversity. These forests also support climate adaptation by mitigating flood risks, reducing peak flows and providing carbon sequestration.
