Change point analysis of phosphorus trends in the Illinois River (Oklahoma) demonstrates the effects of watershed management.
Change point analysis of phosphorus trends in the Illinois River (Oklahoma) demonstrates the effects of watershed management.
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伊利诺伊河（俄克拉荷马州）磷趋势的变化点分析证明了流域管理的效果。
DOI：
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发表时间：
2011
影响因子：
2.4
通讯作者：
J. Romeis
中科院分区：
文献类型：
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作者：
J. Scott;B. Haggard;A. Sharpley;J. Romeis
检测流域管理变化后的水质改善是复杂的流量依赖的浓度和非线性或阈值响应，难以检测与传统的统计技术。在这项研究中，我们评估了长期趋势（1997 - 2009年），总P（TP）浓度在伊利诺伊河的俄克拉荷马州，其主要支流，使用流量调整的TP浓度和回归树分析，以确定具体的日历日期，在P趋势的变化点可能已经发生。所有地点的磷浓度与水流密切相关。在20世纪90年代末，流量调整TP浓度在所有研究地点增加，但这种趋势与1998年后专门针对暴雨流样本的监测做法的变化有关。2003年后，流量调整的TP浓度下降在两个伊利诺伊河网站。这一变化与该流域最大的城市污水处理设施之一产生的出水TP浓度显著下降相吻合。相反，流量调整的TP浓度在一个支流增加，但这条流收到处理后的污水从废水处理设施，在研究期间，污水TP没有显着减少。这项研究的结果表明，如何流TP浓度的长期趋势是难以量化没有一致的长期监测策略，以及如何流量调整可能是强制性的检查这些趋势。此外，该研究还展示了如何检测长期水质数据集的变化需要能够识别变化点和非线性响应的统计方法。
Detecting water quality improvements following watershed management changes is complicated by flow-dependent concentrations and nonlinear or threshold responses that are difficult to detect with traditional statistical techniques. In this study, we evaluated the long-term trends (1997-2009) in total P (TP) concentrations in the Illinois River of Oklahoma, and some of its major tributaries, using flow-adjusted TP concentrations and regression tree analysis to identify specific calendar dates in which change points in P trends may have occurred. Phosphorus concentrations at all locations were strongly correlated with stream flow. Flow-adjusted TP concentrations increased at all study locations in the late 1990s, but this trend was related to a change in monitoring practices where storm flow samples were specifically targeted after 1998. Flow-adjusted TP concentrations decreased in the two Illinois River sites after 2003. This change coincided with a significant decrease in effluent TP concentrations originating with one of the largest municipal wastewater treatment facilities in the basin. Conversely, flow-adjusted TP concentrations in one tributary increased, but this stream received treated effluent from a wastewater facility where effluent TP did not decrease significantly over the study period. Results of this study demonstrate how long-term trends in stream TP concentrations are difficult to quantify without consistent long-term monitoring strategies and how flow adjustment is likely mandatory for examining these trends. Furthermore, the study demonstrates how detecting changes in long-term water quality data sets requires statistical methods capable of identifying change point and nonlinear responses.