科研之友
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摘要
Intensive agricultural practices have critically contributed to the global increase in soil erosion and sediment fluxes. To reduce the impact of these practices, models able to represent the effect of changes in agricultural land-use, farming and conservation practices are needed. Moreover, simulations spanning multi-decadal periods can overcome the potentially confounding influence of climate variability on shorter-term studies of impacts from agricultural change. Conceptual erosion models, such as the Morgan-Morgan-Finney (MMF) model, allow simulation of soil erosion rates and sediment fluxes over longer periods, while still retaining a general description of runoff and sediment generation processes. In addition, the modified-MMF (MMMF) model offers improved representation of vegetation cover effects through measurable plant properties. However, as an annual model, the MMF model does not capture seasonal variability in climate, hydrology and land cover. Here, we propose a new model for humid environments based on the MMF model to address its limitations and improve its predictive ability, while retaining its simplicity and low computational and parameterization requirements. This includes monthly computation, representation of catchment hydrology based on delineation of saturated areas according to the topographic wetness index (TWI), and improved representation of ground and vegetation cover effects. The proposed model, MMF-TWI, was applied in an agricultural catchment in the UK and performance compared to published data and MMMF simulation results. Land cover spatial and temporal variability, crop type as well as farming and conservation practices were found to have a significant influence on simulated sediment yields. Our findings demonstrate: (a) that MMF-TWI model improves predictive ability compared to the MMMF model in humid environments, (b) the importance of capturing sub-annual variability in climate, saturated areas
- 出版日期2018-3-15
