The choice of drain depth in subsurface drainage design affects system performance. Previous studies have focused on investigating the hydrology of shallow drains at discrete locations. However, to our knowledge, no study has investigated the profitability of shallow drains across a wide range of soil and climatic conditions. The main objective of this study was to comparatively evaluate the effects of 75-cm shallow drains versus 125-cm deep drains on profitability and hydrology of subsurface drainage systems across the eastern USA. We conducted DRAINMOD simulations under continuous corn production (Zea mays L.) using 30 years of weather data (1990–2019) for combinations of three factors: two drain depths, four soils, and seven locations. Simulations were optimized for crop production that maximized annual economic return on investment. The results showed that corn yield for shallow drains went from 1.6% increase to –1.3% decrease with increasing growing-season rainfall from northeast to southeast USA. Shallow drains provided the benefit of reduced year-to-year corn yield variability across the region. Corn yield for coarse-textured soil benefited more from shallow drains than fine-textured soil across the region. Even though shallow drains increased annual benefit from higher corn yield under certain soil and weather conditions, they were less profitable than deep drains (lower benefit-cost ratio and higher payback period). The benefit of drainage discharge reduction under shallow drains generally intensified with increasing annual precipitation from northeast to southeast USA. Results were used to develop an empirical equation for estimating the benefit of drainage discharge reduction with shallow drains in the eastern USA. In conclusion, even though shallow drains were less profitable than deep drains, they provide benefits that may be of interest to farmers and policymakers.

地下排水设计中排水深度的选择会影响系统性能。以前的研究侧重于调查离散位置浅排水沟的水文。然而，据我们所知，还没有研究调查过浅排水沟在各种土壤和气候条件下的盈利能力。本研究的主要目的是比较 75 厘米浅排水沟与 125 厘米深排水沟对美国东部地下排水系统盈利能力和水文的影响。我们在连续玉米生产下进行了 DRAINMOD 模拟 ( Zea maysL.) 使用 30 年的天气数据 (1990-2019) 组合三个因素：两个排水深度、四个土壤和七个位置。模拟针对作物生产进行了优化，最大限度地提高了年度经济投资回报。结果表明，随着生长季降雨量从美国东北部到东南部的增加，浅排水沟的玉米产量从 1.6% 增加到 –1.3% 减少。浅层排水系统减少了该地区玉米产量的年际变化。与整个地区的细质地土壤相比，粗质地土壤的玉米产量更多地受益于浅排水沟。尽管在某些土壤和天气条件下，浅排水沟提高了玉米产量的年收益，但与深排水沟相比，它们的利润更低（成本成本比更低，投资回收期更长）。从美国东北部到东南部，随着年降水量的增加，浅排水沟下排水量减少的好处普遍增强。结果被用来开发一个经验方程，用于估计美国东部浅排水沟减少排水沟排放的好处。总之，尽管浅排水沟的利润低于深排水沟，但它们提供了农民和决策者可能感兴趣的好处。