Although many agricultural watersheds rely heavily on riparian buffer adoption to meet water quality goals, design and management constraints in current policies create adoption barriers. Based on focus group feedback, we developed a flexible buffer design paradigm that varies buffer width, vegetation, and harvesting. Sixteen years of daily-scale nutrient and sediment loads simulated with the Soil and Water Assessment Tool (SWAT) were coupled to the three-zone Riparian Ecosystem Management Model (REMM) to compare the effectiveness of traditional, policy-based buffer designs with designs that are more flexible and integrate features important to local farmers. Buffer designs included (i) 10 m grass, (ii) 15 m grass, (iii) 15 m deciduous trees, (iv) 30 m grass and trees, (v) 30 m grass and trees with trees harvested every 3 yr, and (vi) 30 m grass and trees with grass harvested every year. Allowing harvesting in one zone of the buffer vegetation (either trees or grasses) minimally affected water quality, with annual average percent reductions differing by <5% (p > .05; 76-78% for total nitrogen [TN], 51-55% for total phosphorus [TP], and 68% for sediment). Under the highest input loading conditions, buffers with lower removal efficiencies removed more total mass than did buffers with high removal efficiencies. Thus, by focusing on mass reduction in addition to percent reduction, watershed-wide buffer implementation may be better targeted to TN, TP, and sediment reduced. These findings have important implications for informing flexible buffer design policies and enhanced placement of buffers in watersheds impaired by nutrient and sediment.

中文翻译：

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作为缓冲器设计和输入负载的函数的河岸缓冲器有效性

尽管许多农业流域严重依赖河岸缓冲区的采用来实现水质目标，但当前政策中的设计和管理限制造成了采用障碍。根据焦点小组的反馈，我们开发了一种灵活的缓冲区设计范式，可以改变缓冲区宽度、植被和收获。使用土壤和水评估工具 (SWAT) 模拟的 16 年每日规模的养分和沉积物负荷与三区河岸生态系统管理模型 (REMM) 相结合，以比较传统的、基于政策的缓冲区设计与设计的有效性更灵活，并整合了对当地农民很重要的功能。缓冲区设计包括 (i) 10 m 草，(ii) 15 m 草，(iii) 15 m 落叶乔木，(iv) 30 m 草和树木，(v) 30 m 草和树木，每 3 年采伐一次树木，(vi) 每年收获 30 m 的草和带草的树木。允许在缓冲植被（树木或草）的一个区域收获对水质的影响最小，年平均减少百分比相差 <5% (p > .05；总氮 [TN] 为 76-78%，51-55 % 为总磷 [TP]，68% 为沉积物）。在最高输入负载条件下，去除效率较低的缓冲液比去除效率高的缓冲液去除了更多的总质量。因此，除了减少百分比之外，通过关注质量减少，流域范围的缓冲区实施可能更好地针对 TN、TP 和沉积物减少。这些发现对于为灵活的缓冲设计政策提供信息以及在受养分和沉积物损害的流域中加强缓冲放置具有重要意义。