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首页> 外文期刊>Transactions of the ASABE >MODELING IMPACTS OF RESIDENTIAL AND AGRICULTURAL DEVELOPMENT AND BENEFICIAL MANAGEMENT PRACTICE SCENARIOS ON PHOSPHORUS DYNAMICS IN A SMALL WATERSHED
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MODELING IMPACTS OF RESIDENTIAL AND AGRICULTURAL DEVELOPMENT AND BENEFICIAL MANAGEMENT PRACTICE SCENARIOS ON PHOSPHORUS DYNAMICS IN A SMALL WATERSHED

机译：小流域住宅和农业发展及效益管理情景对磷​​动力学的建模影响。

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Both agricultural land uses and residential on-site wastewater systems (OWS) have the potential to be non-point sources of phosphorus (P) in rural watersheds. Watershed-scale computer models are a commonly used tool for evaluating the impacts of increased human development on P dynamics and for evaluating how beneficial management practices (BMPs) can reduce P loading. Many agricultural field BMPs have been evaluated using watershed-scale models; however, no studies have compared their efficacy to OWS BMPs in a mixed land use watershed. The objectives of this research were to (1) use the P on-site wastewater simulator (POWSIM) and the Soil and Water Assessment Tool (SWAT) to simulate different agricultural and residential development scenarios in the Thomas Brook watershed in Nova Scotia, Canada, and evaluate their impacts on sediment and total P (TP) loads and TP concentrations and (2) simulate and evaluate different individual and combinations of select agricultural and OWS BMPs. A 50-year simulation period was used for both the development and BMP scenarios. The development scenarios evaluated included increasing the residential population and conversion of hay fields or pastures to corn-based cropping regimes. The agricultural BMPs evaluated were (1) corn and rotational crop replacement with no-till agricultural land uses and (2) no-till corn. Decreased failure rates, increased watercourse setbacks, disposal field replacement, and the use of high P sorption filter media were the OWS BMPs evaluated. The agricultural development scenarios increased cumulative sediment and P loads at the watershed outlet, while the residential scenarios increased the frequency of hyper-eutrophic conditions in the stream during the last 20 simulated years. Agricultural crop replacement BMPs produced the highest reductions in cumulative sediment (13% to 46%) and TP loads (26% to 34%) but had no observable change on the in-stream trophic status. The OWS BMPs produced small reductions in TP loading (2% to 15%), no sediment load reductions, but had a positive effect on the trophic status. The best ranked combination of agricultural and OWS BMPs resulted in a cumulative TP load reduction of 58%, and the dominant trophic state at the end of the 50-year period was mesotrophic, as compared to eutrophic for the reference simulation. The best combination BMP scenario included replacing corn and rotational crops with pastures, using high P sorption filter media (5000 mg P kg(-1) media), and lowering of the OWS failure rate to 5%. The results of these modeling scenarios showed that agricultural BMPs were most effective in reducing cumulative P loads, while OWS BMPs were effective in mitigating in-stream eutrophication impacts. This study highlights the importance of identifying specific water quality issues that need to be targeted prior to implementing a watershed BMP strategy. Further model refinement and testing are required with improved field measurements to improve model confidence before the model should be used for planning and design purposes.
机译：农业土地利用和居民现场废水处理系统（OWS）都有可能成为农村集水区的面源磷（P）来源。分水岭规模的计算机模型是一种常用的工具，用于评估人类发展的增长对磷动力学的影响以及评估有益的管理实践（BMP）如何减少磷的负荷。已经使用分水岭规模模型对许多农业BMP进行了评估。但是，没有研究将其功效与混合土地利用流域中的OWS BMP进行比较。这项研究的目的是（1）使用P现场废水模拟器（POWSIM）和土壤和水评估工具（SWAT）来模拟加拿大新斯科舍省托马斯布鲁克流域的不同农业和住宅开发方案，并评估它们对沉积物和总磷（TP）负荷和总磷浓度的影响，以及（2）模拟和评估选择的农业和OWS BMP的不同个体和组合。开发和BMP场景都使用了50年的模拟期。评估的发展方案包括增加居民数量，以及将干草田或牧场改成玉米种植制度。评估的农业BMP为（1）免耕农业土地用途的玉米和轮作作物替代品（2）免耕玉米。 OWS BMP评估了降低的故障率，增加的水道挫折，处理场的更换以及高磷吸附过滤介质的使用。在过去的20年中，农业发展情景增加了流域出口处的累积沉积物和磷负荷，而住宅情景增加了河流中富营养化状况的发生频率。替代农作物的BMP产生的累积沉积物减少最多（13％至46％）和TP负荷减少（26％至34％），但河内营养状态没有明显变化。 OWS BMPs的TP负载量略有降低（2％至15％），沉积物负载量没有降低，但对营养状态产生了积极影响。与参考模拟的富营养相比，农业和OWS BMP的最佳组合使总TP负荷减少了58％，并且50年期末的主要营养状态是中营养的。最佳BMP组合方案包括用牧草代替玉米和轮作作物，使用高P吸附过滤介质（5000 mg P kg（-1）介质），并将OWS失败率降低至5％。这些模拟方案的结果表明，农业BMP在减少累积磷负荷方面最有效，而OWS BMP在减轻河流富营养化影响方面有效。这项研究强调了在实施分水岭BMP战略之前确定特定目标水质问题的重要性。在将模型用于计划和设计目的之前，需要对模型进行进一步的完善和测试，并通过改进的现场测量来提高模型的可信度。

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