Cover crops have multiple benefits, such as improving water quality, providing a green manure effect, and storing carbon in the soil. They can, however, reduce drainage significantly during key periods of hydrosystem recharge, especially in winter. The objective of this study was to evaluate the influence of cover crops and/or crop diversification at the watershed scale on water in the downstream watershed of the Aveyron River, based on three scenarios with different management practices. It is an illustrative case study of situations of water imbalance involving 1150 farms, with agricultural fields covering 40,000 ha, of which ca. 40% may be irrigated. The MAELIA model was used to simulate 10 years (2007–2016) of dynamics to estimate the influence of cover crops on water flows. Simulations showed that short-duration cover crops terminated in autumn generally had little influence on water: they decreased drainage slightly in autumn, but the recharge in winter compensated for this decrease and thus did not influence the water dynamics or yields of the succeeding cash crops. Although long-duration cover crops grow for a longer period and are sown more frequently in fields, they also had relatively little influence on water in the region, except for decreasing drainage. A scenario with long-duration cover crops and diversification of rotations was a good compromise for quantitative water management. Diversifying rotations, notably by replacing maize with crops that required less water, compensated for potential negative effects of long-duration cover crops. Although this scenario increased variability depending on the weather year and reduced autumn drainage, it influenced irrigation withdrawals and river flows little over the 10-year period. However, greater variability occurred at the field scale, where cover crops can have more influence. Thus, it is important to adapt the management practices for cover crops in rotations to decrease negative effects, particularly on water availability, which could increase withdrawals in an area that already has a water deficit, and not to decrease yields and thus farmers' profits. Our results are valid for the study area, but these scenarios should be extrapolated to other soil and climate conditions and other rotations and management systems.

覆盖作物有多种好处，例如改善水质、提供绿肥效果以及在土壤中储存碳。然而，它们可以在水系统补给的关键时期显着减少排水，尤其是在冬季。本研究的目的是基于三种不同管理实践的情景，评估流域范围内覆盖作物和/或作物多样化对阿韦龙河下游流域水的影响。这是一个涉及 1150 个农场的水失衡情况的说明性案例研究，农田占地 40,000 公顷，其中约 1000 公顷。40%可以灌溉。MAELIA 模型用于模拟 10 年（2007-2016 年）的动态，以估计覆盖作物对水流的影响。模拟表明，秋季终止的短期覆盖作物通常对水分影响不大：它们在秋季略微减少了排水量，但冬季补给补偿了这种减少，因此不会影响水分动态或后续经济作物的产量。虽然长效覆盖作物的生长时间更长，并且在田间播种的频率更高，但它们对该地区的水影响也相对较小，除了减少排水。长期覆盖作物和轮作多样化的情景是定量水资源管理的一个很好的折衷方案。多样化的轮作，特别是用需要较少水的作物代替玉米，弥补了长期覆盖作物的潜在负面影响。尽管这种情况会根据天气年份增加可变性并减少秋季排水，但它在 10 年期间对灌溉取水量和河流流量的影响很小。然而，更大的变化发生在田间规模，其中覆盖作物可以产生更大的影响。因此，重要的是要调整轮作覆盖作物的管理做法，以减少负面影响，特别是对水资源可用性的负面影响，这可能会增加已经缺水地区的取水量，而不是降低产量，从而降低农民的利润。我们的结果对研究区域有效，但这些情景应外推到其他土壤和气候条件以及其他轮作和管理系统。在 10 年期间，它对灌溉取水量和河流流量的影响很小。然而，更大的变化发生在田间规模，其中覆盖作物可以产生更大的影响。因此，重要的是要调整轮作覆盖作物的管理做法，以减少负面影响，特别是对水资源可用性的负面影响，这可能会增加已经缺水地区的取水量，而不是降低产量，从而降低农民的利润。我们的结果对研究区域有效，但这些情景应外推到其他土壤和气候条件以及其他轮作和管理系统。在 10 年期间，它对灌溉取水量和河流流量的影响很小。然而，更大的变化发生在田间规模，其中覆盖作物可以产生更大的影响。因此，重要的是要调整轮作覆盖作物的管理做法，以减少负面影响，特别是对水资源可用性的负面影响，这可能会增加已经缺水地区的取水量，而不是降低产量，从而降低农民的利润。我们的结果对研究区域有效，但这些情景应外推到其他土壤和气候条件以及其他轮作和管理系统。尤其是在水资源可用性方面，这可能会增加已经缺水地区的取水量，而不是降低产量，从而降低农民的利润。我们的结果对研究区域有效，但这些情景应外推到其他土壤和气候条件以及其他轮作和管理系统。尤其是在水资源可用性方面，这可能会增加已经缺水地区的取水量，而不是降低产量，从而降低农民的利润。我们的结果对研究区域有效，但这些情景应外推到其他土壤和气候条件以及其他轮作和管理系统。