Effects of Agriculture on Erosion and Sedimentation in the Piedmont Province, Maryland
Effects of Agriculture on Erosion and Sedimentation in the Piedmont Province, Maryland
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马里兰州皮埃蒙特省农业对侵蚀和沉积的影响
DOI：
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发表时间：
1975
期刊：
影响因子：
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通讯作者：
J. Costa
中科院分区：
文献类型：
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作者：
J. Costa
一项对马里兰州皮埃蒙特省地表沉积物的研究，使得自18世纪侵蚀性农业用地开始使用以来，构建沉积物产生和沉积的平衡方程成为可能。截断的山前高地土壤剖面意味着大约0.15 m的土壤侵蚀。在西润，一个155平方公里的盆地，由85%的切斯特和马诺土壤组成，这相当于130 × 10−3 hm3/km2的侵蚀沉积物。水库沉积速率表明，34%的侵蚀沉积物已被带出系统。其余的沉积物在流域中以冲积物的形式留在洪泛平原的上游1米，以冲积物和冲积物的形式留在山坡上。储存在洪泛平原的农业沉积物占估计土壤侵蚀的14%。沉积物以岸上沉积为主，沉积速率高达1.6 cm/yr。剩下的52%的侵蚀沉积物以斜坡上的崩积层和冲积层的形式出现，在源头支流的交汇处形成扇形的崩积-冲积层。这些沉积物中的木材放射性碳测年为290±100年。
A study of surficial deposits in the Piedmont province of Maryland has made it possible to construct a balance equation of sediment production and deposition since erosive agricultural land use began in the 1700s. Truncated Piedmont upland soil profiles imply approximately 0.15 m of soil erosion. In Western Run, a basin 155 km2, consisting of 85 percent Chester and Manor soils, this amounts to 130 × 10−3 hm3/km2 of eroded sediment. Reservoir sedimentation rates imply that 34 percent of the eroded sediment has been carried out of the system. The rest of the sediment remains in the watershed as alluvium in the upper 1 m of flood plains and as colluvium and sheetwash deposits on hillslopes. Agricultural sediment stored in flood plains constitutes 14 percent of the estimated soil erosion. The sediment was deposited mostly by overbank deposition at rates as high as 1.6 cm/yr. The remaining 52 percent of the eroded sediment occurs as colluvium and sheetwash deposits on hillslopes and as fan-shaped colluvial-alluvial deposits at junctures of headwater tributaries. Wood from such deposits was radiocarbon dated at 290 ± 100 yr.
A buried junk pile in a flood plain yielded license plates whose dates imply that after 1925 the dump was buried by overbank deposition at rates as high as those for a basin undergoing urbanization. Piedmont basins less than 26 km2 have statistically longer bankfull recurrence intervals than streams with drainage areas greater than 26 km2. This suggests that since the decline of agricultural land use in the early 1900s, small upland tributaries have adjusted to decreased sediment loads by entrenchment into and erosion of sediment deposited since the initiation of colonial agricultural land use.