Twentieth century agricultural drainage creates more erosive rivers
Twentieth century agricultural drainage creates more erosive rivers
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二十世纪的农业排水造成更多侵蚀性河流
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
J. E. Almendinger
中科院分区：
文献类型：
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作者：
S. Schottler;Jason S. Ulrich;P. Belmont;Richard H. Moore;J. Lauer;D. Engstrom;J. E. Almendinger
在美国，以农业为主的流域中的河流受到过量沉积物的影响，其中很大一部分来自非现场，近河道来源。土地利用和气候都与改变河流流量有关，从而增加了河道侵蚀和沉积物负荷。在密西西比盆地上游湿地丰富的景观中，20世纪世纪的作物转换导致了人工排水的加强，这是现代农业的重要组成部分。与此同时，该区域大部分地区的年降雨量有所增加。在分离这些驱动因素的不确定性燃料之间的辩论农业和环境利益的责任和解决方案过多的河流沉积物。为了解开气候和土地利用的影响，我们比较了过去70年来明尼苏达州21个流域的降水量，作物转换和排水洼地面积的变化。自1940年以来，土地利用变化较大的流域的季节性和年度产水量增加了50%以上。平均而言，降水量和作物蒸散量的变化解释了不到一半的增加，其余部分与人工排水和凹陷区域的损失高度相关。流量增加的河流经历了10-40%的河道拓宽，突出了农业最佳管理实践很少解决的沉积物来源。版权所有© 2013约翰威利父子有限公司.
Rivers in watersheds dominated by agriculture throughout the US are impaired by excess sediment, a significant portion of which comes from non‐field, near‐channel sources. Both land‐use and climate have been implicated in altering river flows and thereby increasing stream‐channel erosion and sediment loading. In the wetland‐rich landscapes of the upper Mississippi basin, 20th century crop conversions have led to an intensification of artificial drainage, which is now a critical component of modern agriculture. At the same time, much of the region has experienced increased annual rainfall. Uncertainty in separating these drivers of streamflow fuels debate between agricultural and environmental interests on responsibility and solutions for excess riverine sediment. To disentangle the effects of climate and land‐use, we compared changes in precipitation, crop conversions, and extent of drained depressional area in 21 Minnesota watersheds over the past 70 years. Watersheds with large land‐use changes had increases in seasonal and annual water yields of >50% since 1940. On average, changes in precipitation and crop evapotranspiration explained less than one‐half of the increase, with the remainder highly correlated with artificial drainage and loss of depressional areas. Rivers with increased flow have experienced channel widening of 10–40% highlighting a source of sediment seldom addressed by agricultural best management practices. Copyright © 2013 John Wiley & Sons, Ltd.