Afforestation in a Catchment Context: Understanding the impacts on water yield and salinity

Afforestation, particularly plantation forestry, has emerged as a key land-use strategy in Australia, supported by government and industry initiatives such as the Plantations 2020 Vision. While plantations offer significant economic and environmental benefits—including carbon sequestration and salinity control—their impact on catchment-scale hydrology remains a critical concern. This report examines the hydrological consequences of afforestation, with a focus on changes to water yield and river salinity in a national context where water resources are under increasing stress.

The study explores how afforestation affects the volume and timing of catchment runoff, and its implications for river salinity, particularly in regulated and over-allocated river systems such as the Murray-Darling Basin. With afforestation capable of significantly reducing groundwater recharge and surface runoff, the expansion of plantations may inadvertently conflict with national water reform goals, including the Cap on Diversions, The Living Murray Initiative, and the National Water Initiative.

The report also outlines management strategies to balance the benefits of plantation development with sustainable water resource use. It emphasizes the need for regulatory planning and hydrological assessment tools to ensure plantation expansion does not compromise environmental flows or water entitlements. Ultimately, the report aims to inform land and water managers of the potential trade-offs involved in afforestation, supporting more integrated, catchment-scale decision-making.