渭北台塬区新增坡耕地土壤侵蚀产沙模拟试验研究

Simulated Study of Soil Erosion and Sediment Yield of Newly Increased Sloping Farmland in Weibei Tableland Area

[目的]研究不同放水流量条件下坡面土壤的侵蚀产沙规律,揭示渭北台塬区新增坡耕地坡度及土壤容重对侵蚀程度的影响,为该区坡耕地开发利用提供理论支持和实践指导。[方法]通过室内模拟试验开展研究。[结果]土壤入渗率随放水流量的增大呈现先增大后减小的趋势,且存在明显的转折点,并随容重的增大而减小,径流量随容重和放水量的增大而增大;土壤容重越大,产沙量也越大,容重1.6g/cm3较1.2g/cm3,1.4g/cm3的坡耕地产沙量明显增大;坡度越大,土壤侵蚀越剧烈,在5°坡时,产沙量存在临界值;放水流量越大,产沙量越大,当放水量超过6L/min时,增加趋势更加明显。[结论]渭北台塬区新增坡耕地的易侵蚀程度与土壤容重和坡度密切相关,为减少侵蚀,应控制容重在1.4g/cm3左右,坡度不宜超过15°。

[Objective] The infiltration situation of newly increased sloping farmland of Weibei tableland area was researched, and the impacts of soil volume weight, slope degree and flow discharge on sediment yield were analyzed.[Methods] Simulation test was used in door.[Results] Soil infiltration rate firstly increased and then decreased with the increase of flow discharge, an obvious inflection existed midst, and it decreased with the increase of soil bulk density. Runoff increased with the increase of soil bulk density and flow discharge. The greater bulk density was, the more sediment was, i.e., sediment yield of soil with bulk density of 1.6 g/cm3 was greater than the ones of 1.2 g/cm3 and 1.4 g/cm3. With the increase of slope gradient soil erosion was more heavy. A threshold of slope gradient existed at 5°. The large flow discharge resulted to much sediment yield, this was obvious when the flow discharge was over 6 L/min.[Conclusion] Soil erosion of newly increased sloping farmland in Weibei Tableland area was closely related to soil bulk density and slope gradient. For these reasons, soil bulk density should be small than 1.4 g/cm3, and slope gradient should be less than 15°.