In rainfed agriculture systems, rainfall water management (harvesting, storage, and efficient use) is a key issue. At local scale (i.e., from 100 m to 50 km), the impact of rainfall spatial and temporal variability on crop water availability is seldom addressed. In order to accurately depict the space and time variations of rainfall at local scale, a dense rain-gauges network composed of 45 rain-gauges has been deployed over 28-km2 area, in Burgundy vineyards (North-East France). Rainfall data collected by each rain gauge from 2014 to 2016 were used as input variables in the Lebon et al. (2003) grapevine water balance model. All other climate variables, vineyard, and soil parameters were kept the same for each simulation in order to capture the impact of the sole spatial variability of rainfall on vineyard water status. As rainfall dynamics impact on the vineyard depends on the soil water content, water balance was modeled considering soils with low (50 mm) and medium (150 mm) soil water-holding capacities, representative of the soils of the area. The impact of modeled soil water availability for grapevine was assessed using the water deficit stress index (WDSI), i.e., the relative stomatal conductance. Local rainfall variability throughout the vine vegetative period leads to large variations in WDSI; it varied up to 0.3 within the study area due to because of rainfall spatial variability. Using a set of 34 weather stations at mesoscale level over Burgundy (186 km from North to South), we showed that local rainfall might contribute to change in grapevine water status as large as 50% of the simulated regional water balance spatial variability. Our results indicate that local rainfall and its impacts on agricultural production are probably not sufficiently considered in farming systems, potentially leading to inaccurate water management (cover-crop, irrigation) due to sparse rainfall network.

中文翻译：

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葡萄藤水土平衡对局部尺度降雨空间变异的敏感性

在雨养农业系统中，雨水管理（收集、储存和有效利用）是一个关键问题。在局部范围内（即从 100 m 到 50 km），很少涉及降雨空间和时间变化对作物可用水量的影响。为了准确描绘局部尺度降雨的时空变化，在勃艮第葡萄园（法国东北部）的 28 平方公里区域内部署了由 45 个雨量计组成的密集雨量计网络。每个雨量计从 2014 年到 2016 年收集的降雨数据被用作 Lebon 等人的输入变量。(2003) 葡萄藤水平衡模型。所有其他气候变量、葡萄园和土壤参数在每次模拟中都保持不变，以捕捉降雨的唯一空间变异性对葡萄园水状况的影响。由于降雨动态对葡萄园的影响取决于土壤含水量，水平衡模型考虑了低（50 毫米）和中（150 毫米）土壤持水能力的土壤，代表了该地区的土壤。使用水分亏缺压力指数（WDSI），即相对气孔导度，评估模拟土壤水分对葡萄藤的影响。整个藤蔓植物生长期间的局部降雨变化导致 WDSI 的巨大变化；由于降雨空间变异性，它在研究区域内变化高达 0.3。使用一组 34 个中尺度水平的勃艮第气象站（从北到南 186 公里），我们表明，当地降雨可能导致葡萄藤水状况的变化，高达模拟区域水平衡空间变异的 50%。