Human amplified changes in precipitation-runoff patterns in large river basins of the Midwestern United States
Human amplified changes in precipitation-runoff patterns in large river basins of the Midwestern United States
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DOI：
10.5194/hess-21-5065-2017
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发表时间：
2017-10-09
影响因子：
6.3
通讯作者：
Foufoula-Georgiou, Efi
中科院分区：
文献类型：
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作者：
Kelly, Sara A.;Takbiri, Zeinab;Foufoula-Georgiou, Efi
自19世纪以来，土地覆盖从草原、湿地和阔叶林到行栽作物农业和城市中心的完全转变被认为引起了美国中西部上游水文的深刻变化。在本研究中，我们调查了跨越气候和土地利用梯度的四个大型（23 000-69 000 km（2））中西部河流流域，以了解过去79年来气候和农业排水如何影响流域水文。我们使用每日，每月和每年的流量指标来记录径流量的变化，并讨论这些变化的背景下，降水和土地利用的变化。自1935年以来，该地区的流量、降水量、人工排水范围以及玉米和大豆种植面积都有所增加。在广泛排水的流域，我们观察到低流量增加2至4倍，高流量和极端流量增加1.5至3倍。使用水预算，我们确定，自1975年以来，在密集排水和耕作的流域，蓄水期减少了30- 200%，但在农业较少的流域，蓄水期增加了大约30%。在所有流域，储存量在春季和夏季普遍减少，在秋季和冬季增加。因此，存储和增强的水文连通性和人工农业排水赋予的效率的损失似乎已经放大了径流响应降水增加在中西部。未来降水量的增加可能会进一步加强排水措施，增加流量。径流量的增加对洪水风险、河道调整、沉积物和营养物的输送都有影响，并对中西部的农业和水资源管理提出了独特的挑战。需要更好地记录现有和未来的排水瓦和沟渠安装，以进一步了解气候与排水在多个空间和时间尺度上的作用。
Complete transformations of land cover from prairie, wetlands, and hardwood forests to row crop agriculture and urban centers are thought to have caused profound changes in hydrology in the Upper Midwestern US since the 1800s. In this study, we investigate four large (23 000-69 000 km(2)) Midwest river basins that span climate and land use gradients to understand how climate and agricultural drainage have influenced basin hydrology over the last 79 years. We use daily, monthly, and annual flow metrics to document streamflow changes and discuss those changes in the context of precipitation and land use changes. Since 1935, flow, precipitation, artificial drainage extent, and corn and soybean acreage have increased across the region. In extensively drained basins, we observe 2 to 4 fold increases in low flows and 1.5 to 3 fold increases in high and extreme flows. Using a water budget, we determined that the storage term has decreased in intensively drained and cultivated basins by 30-200 % since 1975, but increased by roughly 30 % in the less agricultural basin. Storage has generally decreased during spring and summer months and increased during fall and winter months in all watersheds. Thus, the loss of storage and enhanced hydrologic connectivity and efficiency imparted by artificial agricultural drainage appear to have amplified the streamflow response to precipitation increases in the Midwest. Future increases in precipitation are likely to further intensify drainage practices and increase streamflows. Increased streamflow has implications for flood risk, channel adjustment, and sediment and nutrient transport and presents unique challenges for agriculture and water resource management in the Midwest. Better documentation of existing and future drain tile and ditch installation is needed to further understand the role of climate versus drainage across multiple spatial and temporal scales.