Global Sustainability and Life Cycle Consultant, LLC, Athens, Georgia, United States of America.
U.S. Environmental Protection Agency, Office of Research and Development, Computational Exposure Division, Athens, Georgia, United States of America.
PLoS One. 2019 May 10;14(5):e0216452. doi: 10.1371/journal.pone.0216452. eCollection 2019.
Rainwater harvesting (RWH) has been used globally to address water scarcity for various ecosystem uses, including crop irrigation requirements, and to meet the water resource needs of a growing world population. However, the costs, benefits and impacts of alternative crop types and irrigation practices is challenging to evaluate comprehensively. We present an assessment methodology to evaluate the sustainability of agricultural systems as applied to a southeastern U.S. river basin. We utilized detailed, crop-level cultivation information to calculate sustainability indicators (relative to well-water irrigation) at the basin scale (6-digit Hydrologic Unit Codes). 40 design configurations comprising crop types and irrigation practices were evaluated to demonstrate the methodology's robustness. Four RWH designs and four major crops (pasture-grass, soybeans, corn, and cotton) resembling current practices were evaluated, as well as six combined systems (combined RWH and well-water systems) with four globally representative crops (corn, soybeans, wheat, and quinoa). Sustainability scores were calculated by integrating seven life cycle impact indicators (cumulative energy demand, CO2 emission, blue water use, ecotoxicity, eutrophication, human health-cancer, and life cycle costs). At a basin-wide RWH adoption rate of 25%, the benefits, relative to 100% well-water, of the RWH systems irrigating soybeans and supported with well-water (0.4 well-water: 0.6 RWH) provided cumulative energy savings of 39 Peta Joule and reductions in CO2 emission, blue water use, ecotoxicity, eutrophication, and human health-cancer at 1.9 Mt CO2 eq., 6.9 Gm3, 5.7 MCTU, 6.6 kt N eq., and 0.07 CTU, respectively. These benefits increased linearly with RWH scaling variables including the adoption rates, system service life, crop area, and water needs. Our methodology integrates the three pillars of agricultural sustainability specific to rainwater harvesting into a single score. It is applicable to other locations worldwide facing water scarcity by modifying the RWH system design, selecting other crop types, and obtaining appropriate data.
雨水收集（RWH）已在全球范围内用于解决各种生态系统的用水短缺问题，包括作物灌溉需求，并满足不断增长的世界人口对水资源的需求。然而，替代作物类型和灌溉实践的成本、效益和影响很难全面评估。我们提出了一种评估方法，用于评估应用于美国东南部流域的农业系统的可持续性。我们利用详细的作物水平种植信息来计算流域尺度（6 位数字水文单元代码）的可持续性指标（相对于井水灌溉）。评估了 40 种设计配置，包括作物类型和灌溉实践，以展示该方法的稳健性。评估了四种 RWH 设计和四种主要作物（牧场草、大豆、玉米和棉花），以及四种类似于当前做法的设计，以及六种组合系统（RWH 和井水系统的组合）和四种全球代表性作物（玉米、大豆、小麦和藜麦）。通过整合七个生命周期影响指标（累积能源需求、CO2 排放、蓝水使用、生态毒性、富营养化、人类健康-癌症和生命周期成本）来计算可持续性得分。在流域范围内 RWH 采用率为 25%的情况下，与 100%井水相比，用井水（0.4 井水：0.6 RWH）灌溉大豆的 RWH 系统的收益提供了 39 太焦耳的累积能源节约，并减少了 CO2 排放、蓝水使用、生态毒性、富营养化和人类健康-癌症分别为 1.9 Mt CO2eq、6.9 Gm3、5.7 MCTU、6.6 kt N eq 和 0.07 CTU。这些好处随着 RWH 规模变量的线性增加而增加，包括采用率、系统服务寿命、作物面积和需水量。我们的方法将农业可持续性的三个支柱（具体针对雨水收集）整合到一个单一的分数中。通过修改 RWH 系统设计、选择其他作物类型和获取适当的数据，它可以适用于全球其他面临水资源短缺的地区。
