Assessing catchment-scale erosion and yields of suspended solids from improved temperate grassland
Assessing catchment-scale erosion and yields of suspended solids from improved temperate grassland
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DOI：
10.1039/b921584k
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发表时间：
2010-01-01
影响因子：
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通讯作者：
Quinton, J. N.
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文献类型：
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作者：
Bilotta, G. S.;Krueger, T.;Quinton, J. N.
本文量化了悬浮固体（SS）的产量从源头流域管理的改善温带草原，提供了第一个直接的，集水规模的证据，从这个土地利用在英国的侵蚀率，并评估对水生生态系统构成的威胁。在2006-2007年水文季节，在德文郡（英国）的登布鲁克水源集水区的一级通道进行了高分辨率的集水水文和SS和挥发性有机物（VOM）的浓度监测。广泛使用的“额定曲线”（排放浓度）的方法来估计产量的SS，但由以前的研究人员证明，这项研究表明，排放是一个穷人的预测SS浓度，因此，从这种技术估计的任何产量可能是高度不确定的。尽管如此，为了提供与以前关于其他土地用途/来源的研究相比较的产量估计，采用了这种技术，尽管是在一个基于不确定性的框架内。研究结果表明，与通常的看法相反，草地可以侵蚀景观，从这个集水区的SS产量估计为0.54和1.21吨公顷（-1）年（-1）之间。就现场侵蚀问题而言，这一侵蚀速率并未明显超过英国常用的“可容忍”阈值（类似于1吨公顷（-1）y（-1））。在非现场侵蚀问题方面，有人认为，在这里，作为一个整体的年度数字的SS产量的传统表达几乎没有相关性的水质和地表沃茨的生态状况，因此，一个替代技术（浓度-频率曲线）是在本文中开发的特定目的，评估所造成的生态威胁的SS输送到地表沃茨。这项技术表明，在集水区出口处记录的SS浓度经常超过水质准则，如欧盟淡水渔业指令（78/659/EC），并对水生生物构成严重威胁。有人建议，未能认识到改善温带草原作为一个潜在的颗粒物来源可能会导致不遵守地表沃茨水质准则，生态状况恶化和水质补救措施的失败。
This paper quantifies the yields of suspended solids (SS) from a headwater catchment managed as improved temperate grassland, providing the first direct, catchment-scale evidence of the rates of erosion from this land-use in the UK and assessing the threat posed to aquatic ecosystems. High-resolution monitoring of catchment hydrology and the concentrations of SS and volatile organic matter (VOM) were carried out in the first-order channel of the Den Brook headwater catchment in Devon (UK) during the 2006-2007 hydrological season. The widely used 'rating curve' (discharge-concentration) approach was employed to estimate yields of SS, but as demonstrated by previous researchers, this study showed that discharge is a poor predictor of SS concentrations and therefore any yields estimated from this technique are likely to be highly uncertain. Nevertheless, for the purpose of providing estimates of yields that are comparable to previous studies on other land uses/sources, this technique was adopted albeit in an uncertainty-based framework. The findings suggest that contrary to the common perception, grasslands can be erosive landscapes with SS yields from this catchment estimated to be between 0.54 and 1.21 t ha(-1) y(-1). In terms of on-site erosion problems, this rate of erosion does not significantly exceed the commonly used 'tolerable' threshold in the UK (similar to 1 t ha(-1) y(-1)). In terms of off- site erosion problems, it is argued here that the conventional expression of SS yield as a bulk annual figure has little relevance to the water quality and ecological status of surface waters and therefore an alternative technique (the concentration-frequency curve) is developed within this paper for the specific purpose of assessing the ecological threat posed by the delivery of SS into surface waters. This technique illustrates that concentrations of SS recorded at the catchment outlet frequently exceed the water quality guidelines, such as those of the EU Freshwater Fisheries Directive (78/659/EC), and pose a serious threat to aquatic organisms. It is suggested that failure to recognise improved temperate grasslands as a potential source of particulate material could result in the non-compliance of surface waters to water quality guidelines, deterioration of ecological status and failure of water quality remediation measures.