Hydrological effects of forest plantation clear-cut on water availability: Consequences for downstream water users

Abstract

Study Region: São Paulo State, Brazil. Study Focus: This study assessed the influence of forest plantations on streamflow in a gauged catchment (85 ha), covered with fast-growing Eucalyptus sp. plantations. One strategy for reducing the effects of plantations on streamflow is to reduce the area of a catchment occupied by forest, and in this context, our objectives were to simulate the effects on streamflow of different proportions of forest cover (70%, 50% and 0% of the forest cover). Moreover, we used low-flow indices (Q90 and 7Q10) to examine the effects of such scenarios on water availability for downstream users. New Hydrological Insights: Fast-growing forest plantation areas have been expanding globally, with simultaneously increasing concerns about the water consumption of these forests, especially in water-limited regions with consequences for downstream users. Simulations of scenarios with varying forest cover proportions showed an annual streamflow increase of 90% when clear-cutting had removed the forest cover in the catchment. The 100% forest cover scenario produced rates of streamflow below the low flow indices, resulting in less water availability for downstream water users. The reduction in forest cover proportion at the catchment scale promoted an attenuation of water use. Therefore, forest plantation management should adopt management strategies such as regulating the forest cover proportion to minimize the effects on water supply for downstream water users. Keywords: Clear-cut proportion, Flow duration curve, Eucalyptus forest, Low flow indices, Forest age mosaic, Hydrological model