Terraces of the Yellow River are among the most crucial geomorphological landforms pertaining to human survival on the Loess Plateau. After more than half a century of surface flood irrigation, rapid rises in groundwater levels have led to frequent geological disasters, causing a rapid short-term evolution of Yellow River terraces, and an increasingly serious contradiction between this rapid evolution and human survival. However, the process by which water transfers through the thick loess vadose zone and causes a rapid groundwater response within months or years remains controversial. Using the Heitai platform of Yellow River terrace IV as an example, we found, on the basis of regional geological surveys, that at least 112 tectonically-induced cracks have developed in this area. We contend that the superimposed effects of earthquake ground motions from historical and ancient earthquakes since the Late Pleistocene have driven the development of such densely distributed cracks in the loess layer. These cracks, together with a series of fault planes generated by NE-directed extrusive stress at the regional scale, constitute a potential network of preferential channels for water transport within the Heitai platform. Combined with the results of a large-scale in situ ponding test and electrical resistivity tomography, we found that this network of cracks helps to establish catchment areas within the loess layer, thereby increasing soil saturation at a more extensive spatial scale, which may then increase the overall movement velocity of the wetting front. We semi-quantified the efficiency of the crack network in enhancing the recharge of surface water to groundwater, and suggested that the impact of human and tectonic activities substantially shortens the response time of groundwater to surface water, with the reduced time far exceeding one order of magnitude. The results of a field investigation of structural traces and terrace groundwater after the Ms 6.2 Jishishan earthquake on 18 December 2023 further emphasize that a causal mechanism of human and tectonic activities leading to the rapid short-term evolution of groundwater distribution patterns may be universally applicable to all Yellow River terraces on the Loess Plateau. This study mitigates the long-standing controversy concerning the mode of surface water infiltration, including piston flow and preferential flow, and the infiltration medium by which rapid surface water recharge to groundwater occurs in loess areas over short time periods.

中文翻译：

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人类和构造活动对黄土高原黄河上游梯田地下水的影响


黄河梯田是关系到黄土高原人类生存的最重要地貌地貌之一。经过半个多世纪的地表漫灌溉，地下水位的快速上升导致了地质灾害频发，造成了黄河梯田的快速短期演变，这种快速演变与人类生存之间的矛盾日益严重。然而，水通过厚厚的黄土包气带并在数月或数年内导致地下水快速响应的过程仍然存在争议。以黄河四号台地黑台台地为例，在区域地质调查的基础上，发现该地区至少发育了 112 条构造诱发裂缝。我们认为，晚更新世以来历史和古代地震的地震运动的叠加效应推动了黄土层中这种密集分布的裂缝的发展。这些裂缝与区域尺度上由 NE 方向的挤压应力产生的一系列断层面一起，构成了黑台台内潜在的优先水运通道网络。结合大规模原位积水测试和电阻率层析成像的结果，我们发现这种裂缝网络有助于在黄土层内建立集水区，从而在更广泛的空间尺度上增加土壤饱和度，从而可能增加润湿前沿的整体运动速度。 我们半量化了裂缝网络在增强地表水对地下水补给方面的效率，并提出人类和构造活动的影响大大缩短了地下水对地表水的响应时间，缩短的时间远远超过一个数量级。2023 年 12 月 18 日吉石山 Ms 6.2 地震后构造痕迹和阶地地下水的实地调查结果进一步强调，人类和构造活动导致地下水分布模式快速短期演变的因果机制可能普遍适用于黄土高原的所有黄河阶地。本研究缓解了长期以来关于地表水渗透模式（包括活塞流和优先流）以及黄土地区在短时间内地表水快速补给地下水的渗透介质的争议。