Large-domain hydrological models are increasingly needed to support water-resource assessment and management in large river basins. Here, we describe results for the first Brazilian application of the SPAtially Referenced Regression On Watershed attributes (SPARROW) model using a new open-source modeling and interactive decision support system tool (RSPARROW) to quantify the origin, flux, and fate of total nitrogen (TN) in two sub-basins of the Grande River Basin (GRB; 43,000 km2). Land under cultivation for sugar cane, urban land, and point source inputs from wastewater treatment plants was estimated to each contribute approximately 30% of the TN load at the outlet, with pasture land contributing about 10% of the load. Hypothetical assessments of wastewater treatment plant upgrades and the building of new facilities that could treat currently untreated urban runoff suggest that these management actions could potentially reduce loading at the outlet by as much as 20–25%. This study highlights the ability of SPARROW and the RSPARROW mapping tool to assist with the development and evaluation of management actions aimed at reducing nutrient pollution and eutrophication. The freely available RSPARROW modeling tool provides new opportunities to improve understanding of the sources, delivery, and transport of water-quality contaminants in watersheds throughout the world.

中文翻译：

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RSPARROW 建模工具在巴西格兰德河流域估算河流中的总氮源和评估源头减少管理方案中的应用

越来越需要大域水文模型来支持大流域的水资源评估和管理。在这里，我们使用新的开源建模和交互式决策支持系统工具 (RSPARROW) 来量化总氮的来源、通量和归宿，描述了巴西首次应用空间参考回归流域属性 (SPARROW) 模型的结果(TN) 位于格兰德河流域 (GRB；43,000 平方公里) 的两个子流域。据估计，甘蔗耕地、城市土地和废水处理厂的点源输入各占出口总氮负荷的 30% 左右，牧场占负荷的 10% 左右。对污水处理厂升级和建设可处理当前未经处理的城市径流的新设施的假设评估表明，这些管理措施有可能将出口处的负荷减少 20-25%。本研究强调了 SPARROW 和 RSPARROW 绘图工具在协助制定和评估旨在减少养分污染和富营养化的管理措施方面的能力。免费提供的 RSPARROW 建模工具提供了新的机会，可以提高对世界各地流域水质污染物的来源、输送和运输的了解。本研究强调了 SPARROW 和 RSPARROW 绘图工具在协助制定和评估旨在减少养分污染和富营养化的管理措施方面的能力。免费提供的 RSPARROW 建模工具提供了新的机会，可以提高对世界各地流域水质污染物的来源、输送和运输的了解。本研究强调了 SPARROW 和 RSPARROW 绘图工具在协助制定和评估旨在减少养分污染和富营养化的管理措施方面的能力。免费提供的 RSPARROW 建模工具提供了新的机会，可以提高对世界各地流域水质污染物的来源、输送和运输的了解。