دانلود رایگان مقاله انگلیسی تخمین پاسخ فرسایش خاک در استفاده از زمین، تغییرات پوششی در حوضچه Loess Plateau، چین - الزویر 2018

abstract

The vegetation restoration project, named the Grain to Green Program, has been operating for more than ten years in the upper reaches of the Beiluo River basin, located in the Loess Plateau of China. It is significant to be able to estimate the success of preventing soil erosion. In this study, the Revised Universal Soil Loss Equation (RUSLE) and the Sediment Distributed Delivery (SEDD) model were used to assess the annual soil loss derived from water erosion. The results showed that the study area suffered from primary land use changes, with increasing grassland and forest and decreasing farmland from 1990 to 2010. Based on that, the average soil erosion modulus decreased from 18,189.72 t/(km2 a) in 1990– 7408.93 t/(km2 a) in 2000 and 2857.76 t/(km2 a) in 2010. Compared with 1990, the average soil erosion modulus decreased by 59.0% and 84.3% for 2000 and 2010, respectively. Benefiting from the increased vegetation coverage and improved ecological environment, the soil erosion in this study area clearly declined. This research also found that the distribution of the three years of soil erosion was similarly based on topographic factors. The soil erosion modulus varied with different land use types and decreased in the order of residential area4farmland4grassland4forest. The average soil erosion modulus gradually increased with the increase of the slope gradient, and 76.08% of the total soil erosion was concentrated in the region with a gradient more than 15 degrees. The soil erosion modulus also varied with slope aspects in the order of sunny slope4half-sunny slope4half-shady slope4shady slope. This research provides useful reference for soil and water conservation and utilization in this area and offers a technical basis for using the RUSLE to estimate soil erosion in the Loess Plateau of China

5. Conclusion

This study researched the land use changes from 1990 to 2000 and 2010 in the upper reaches of the Beiluo River basin. The result was presented by simulating the spatial distribution of soil erosion and sediment yield at a watershed scale with the combination of RUSLE and SEDD models. The distribution of soil erosion in different topographic factors was also analyzed. The conclusion can be summarized as follows:

From 1990–2000, farmland slowly decreased, whereas grassland and forest slowly increased. From 2000–2010, farmland rapidly decreased, whereas grassland and forest rapidly increased. In 2010, farmland area decreased by 68.8% and the grassland and forest increased by 27.0% and 18.15%, respectively. The RUSLE and SEDD models were calibrated using the observed sediment load data. There was good agreement between the measured and simulated values, indicating that the simulation results were satisfactory. Scenario modeling indicated that the soil and water conservation measures were effective for sediment yield reduction in the study area. The amount of soil erosion and sediment yield gradually decreased from 1990 to 2010. The average soil erosion modulus decreased from 18,189.72 t/(km2 yr) in 1990–7408.93 t/ (km2 yr) in 2000 and to 2857.76 t/(km2 yr) in 2010. The average sediment yield modulus decreased from 14,093.31 t/(km2 yr) in 1990–5997.65 t/(km2 yr) in 2000 and to 2394.37 t/(km2 yr) in 2010. The areas of soil erosion of grades Ⅰ, Ⅱ and Ⅲ gradually increased, whereas the areas of soil erosion of grades Ⅳ, Ⅴ and Ⅵ gradually decreased from 1990 to 2010. The remarkable reduction in sediment load measured at the Wuqi station is attributable to the implementation of soil and water conservation and subsequent Grain to Green program.