Plants versus streams: Their groundwater‐mediated competition at “El Morro,” a developing catchment in the dry plains of Argentina
Plants versus streams: Their groundwater‐mediated competition at “El Morro,” a developing catchment in the dry plains of Argentina
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DOI：
10.1002/hyp.14188
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发表时间：
2020-09
影响因子：
3.2
通讯作者：
E. Jobbágy;S. Lorenzo;N. Buono;R. Páez;Y. Diaz;Victoria A. Marchesini;M. Nosetto
中科院分区：
文献类型：
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作者：
E. Jobbágy;S. Lorenzo;N. Buono;R. Páez;Y. Diaz;Victoria A. Marchesini;M. Nosetto
我们的理解地下水如何介导蒸散/径流分区仍然支离破碎，在不断变化的植被条件下的集水研究可以提供一个有用的框架整合。我们在阿根廷中部的一个平坦的沉积干燥集水区探索了这种分区，其中原生植被被干旱作物取代，伴随着地下侵蚀突然形成的地下水补给河流（即，sapping）情节。历史记录显示地下水位普遍上升（平均约0.3 m y−1）。地下水位和流基流季节性波动，在温暖的雨季最低，表明蒸发排放，而不是降雨形状饱和流。昼夜地下水位波动表明，植物吸收是广泛的地下水位较浅（<3米），但仅限于深根牧豆林，他们是深（7-10米）。MODIS和LANDSAT NDVI揭示了原生植被的长期绿化，包括新的湿地，但不是农田，这表明农业下的蒸散-地下水位调节更有限。接近最深（20米）和最活跃的切口，地下水位和绿化下降，流基流没有季节性波动，暗示脱钩蒸散。强烈的生态和地貌变化，在这个集水区暴露的相互作用的五种机制，包括（a）不饱和的吸收和（B）河岸和（c）分布吸收饱和区的植物，以及（d）加深切口和（e）河流沉积物沉积在河岸带。认识到这些机制与地下水的复杂相互作用对于预测和管理南美洲干旱平原未来的水文变化至关重要。
Our understanding of how groundwater mediates evapotranspiration/streamflow partitioning is still fragmented and catchment studies under changing vegetation conditions can provide a useful frame for integration. We explored this partition in a flat sedimentary dry catchment in central Argentina in which the replacement of native vegetation with rainfed crops was accompanied by the abrupt formation of groundwater‐fed streams by subsurface erosion (i.e., sapping) episodes. Historical records indicated widespread water table rises (~0.3 m y−1 on average). Groundwater level and stream baseflow fluctuated seasonally with minima in the warm rainy season, indicating that evaporative discharge rather than rainfall shapes saturated flows. Diurnal groundwater level fluctuations showed that plant uptake was widespread where water tables are shallow (<3 m) but restricted to deep‐rooted Prosopis forests where they are deep (7–10 m). MODIS and LANDSAT NDVI revealed a long‐term greening for native vegetation, new wetlands included, but not for croplands, suggesting more limited evapotranspiration‐groundwater level regulation under agriculture. Close to the deepest (20 m) and most active incisions, groundwater level and greenness declined and stream baseflow showed no seasonal fluctuations, hinting decoupling from evapotranspiration. Intense ecological and geomorphological transformations in this catchment exposed the interplay of five mechanisms governing evapotranspiration/streamflow partition including (a) unsaturated uptake and both (b) riparian and (c) distributed uptake from the saturated zone by plants, as well as (d) deepening incisions and (e) sediment deposits over riparian zones by streams. Acknowledging the complex interplay of these mechanisms with groundwater is crucial to predict and manage future hydrological changes in the dry plains of South America.