关键词: 森林植被变化, 径流形成机制, 水文模拟, 尺度问题, 同位素水文学, 优先流, 水力传导度

Abstract: Runoff generation mechanism is one of the key research focuses in the hydrological study on which more and more attention is concentrated.The complexity of hydrological processes such as scale dependence and nonlinear behavior resulted from the widespread spatial heterogeneity and temporal variability of hydrological environment and fluxes makes it very difficult,given that without detailed understanding of the physical processes,to extrapolate the information from one area to another or from one scale to another.Current generation of physically based,distributed parameter models could accommodate the assessment of hydrological impacts of forest vegetation changes to certain degree in comparison with traditional approaches.However,the confidence of such models and the scale issues highlights current and future research needs in the forest vegetation influences on the runoff generation and delivery mechanisms.Three major research methods being adopted are hydrometry,tracer/isotope tracing,and dynamic calculation at the spatial scale from hillslopes to watershed.The current understanding of forest vegetation influences on the runoff generation could be summarized as (a)runoff is controlled by variable source area mechanisms for forested watershed,(b)major runoff components for forested watershed are saturated surface runoff,subsurface runoff,and groundwater runoff,(c)co existing and shifting of different runoff generation mechanisms,and (d)preferential flow is a key factor in controlling runoff generation for forested watershed.

Key words: forest vegetation change, runoff generation mechanisms, hydrological modeling, scale issue, tracer/isotope hydrology, preferential flow, hydraulic conductivity