There is a critical need for a national agroecosystem model for conservation policy and environmental planning, driven by issues including harmful algal blooms, water scarcity, flooding, and other weather‐related extremes. In this study, we illustrate the feasibility of a national agroecosystem model that will downscale processes to individual fields and first‐order channels. We propose to conceptually divide the conterminous United States (U.S.) into process domains as a framework for simulating processes and management at relevant scales. Specifically, we are proposing five domains: field (1–50 ha), transition (0.2–2.0 km²), headwater (1–15 km²), tributaries (15–150 km²), and main river (>150 km²). The proposed conceptual framework hydrologically connects fields across the U.S. using the National Hydrography Dataset (NHDPlus version 2). Parameterizing the Soil and Water Assessment Tool for the national agroecosystem model resulted in 4,880,000 agricultural fields, 2,250,000 non‐agricultural hydrologic response units, and 7,130,000 transition, 1,610,000 headwater, 591,000 tributary, and 432,400 main channels. Application of this framework was shown for Hydrologic Unit Code 07120002 in central Illinois and Indiana to demonstrate the feasibility of the approach using data that is readily available across the U.S. The new connectivity framework has the potential to dramatically improve national conservation and environmental assessments performed by U.S. Department of Agriculture and U.S. Environmental Protection Agency.

中文翻译：

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基于运输过程和管理实践的国家农业生态系统模型的连通性概念框架

迫切需要一个国家农业生态系统模型来进行保护政策和环境规划，其驱动因素包括有害藻华，缺水，洪水和其他与天气有关的极端事件。在这项研究中，我们说明了建立国家农业生态系统模型的可行性，该模型会将过程缩减到各个领域和一级渠道。我们建议从概念上将最终的美国（US）划分为过程域，作为在相应规模上模拟过程和管理的框架。具体来说，我们提出了五个领域：野外（1–50公顷），过渡（0.2–2.0 km ²），源头（1–15 km ²），支流（15–150 km ²）和主要河流（> 150 km）²）。拟议中的概念框架使用“国家水文数据集”（NHDPlus版本2）在全美范围内将各个领域联系起来。为国家农业生态系统模型参数化土壤和水评估工具产生了488万个农田，225万个非农业水文响应单位和713万个过渡，161万源水，591,000个支流和432,400个主要渠道。该框架在伊利诺伊州中部和印第安纳州的水文部门代码07120002中的应用得到了展示，以证明该方法的可行性，该方法使用了美国各地现有的数据。新的连通性框架有可能极大地改善美国进行的国家保护和环境评估农业部和美国环境保护局。