Trends in recent reservoir sedimentation rates in Southwestern Ohio
Trends in recent reservoir sedimentation rates in Southwestern Ohio
复制标题
俄亥俄州西南部近期水库沉积率的趋势
DOI：
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
James Hayes
中科院分区：
文献类型：
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作者：
W. Renwick;K. Carlson;James Hayes
摘要：美国农田的土壤侵蚀率正在下降。这种减少预计会对产沙量产生两种影响：1）产沙量总体减少; 2）相对于高地沉积物来源，河道侵蚀的重要性日益增加。在这里，我们检查最近的沉积速率在12个水库在西南俄亥俄州县，以确定沉积速率是否下降，以及是否有证据表明，转移到通道沉积物来源。其中一个县主要是城市，当地救济程度高，而另一个县主要是农业，救济程度低。在每种情况下，研究了大范围的水库规模（70平方公里的流域面积或24平方米）。先前的沉积物调查可用于研究的一些水库。测得的沉积速率为1200 m3 km−2 yr−1（2.5 mi−2 yr−2）。城市县的沉积率一般高于农业县。最近（自1980年以来）的沉积速率与那些从20世纪中期世纪的比较表明，沉积速率下降，在农业县，大概是由于改善土壤保护措施，而在城市县仍然很高。在农业县的沉积速率遵循正常的模式，减少每单位流域面积的沉积量与流域面积的增加，这表明该地区的渠道系统很可能作为沉积物汇。相比之下，在城市县有没有减少，随着流域面积的增加，沉积速率，这表明在该景观的渠道作为有效的管道和/或净沉积物来源。这些趋势突出了需要更新我们的水库沉积数据库，以确定趋势是局部的还是广泛的。
ABSTRACT: Soil erosion rates on U.S. cropland are declining. This decline can be expected to have two effects on sediment yield: 1) an overall decrease in sediment yield; and 2) an increasing importance of channel erosion relative to upland sediment sources. Here we examine recent sedimentation rates in 12 reservoirs in two southwest Ohio counties to determine whether sedimentation rates are declining, and whether there is evidence for a shift to channel sediment sources. One of the two counties is primarily urban with high local relief, while the other is primarily agricultural with low relief. In each case a large range of reservoir sizes was studied ( 70 km2 drainage area or 24 mi2). Previous sediment surveys are available for some of the reservoirs studied. Measured sedimentation rates range from 1200 m3 km−2 yr−1 ( 2.5 mi−2 yr−2). Sedimentation rates are generally higher in the urban county than the agricultural one. Comparison of recent (since ∼1980) sedimentation rates with those from the mid-20th Century indicate that sedimentation rates are declining in the agricultural county, presumably as a result of improved soil conservation practices, while those in the urban county remain high. In the agricultural county sedimentation rates follow the normal pattern of decreasing sedimentation per unit drainage area with increasing drainage area, indicating that the channel systems in the area are likely functioning as sediment sinks. In contrast, in the urban county there is no decrease in sedimentation rate with increasing drainage area, indicating that the channels in that landscape are functioning as efficient conduits and/or net sediment sources. These trends highlight the need to update our reservoir sedimentation databases to determine whether the trends are local or widespread.