Land subsidence caused by seasonal groundwater level fluctuations in Kawajima (Japan) and one-dimensional numerical modeling with an evolutionary algorithm
Land subsidence caused by seasonal groundwater level fluctuations in Kawajima (Japan) and one-dimensional numerical modeling with an evolutionary algorithm
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DOI：
10.1007/s10040-022-02566-6
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发表时间：
2022-12
影响因子：
2.8
通讯作者：
Kento Akitaya;M. Aichi
中科院分区：
文献类型：
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作者：
Kento Akitaya;M. Aichi
通过数据整理和数值模拟，研究了日本川岛县地面沉降的原因。尽管从长远来看，水头逐渐增加，但地面沉降仍在发展。考虑到地下水开采的时间变化和深度分布、地层的收缩性以及水文地质结构的复杂性，提出农业地下水开采是地面沉降的主要诱因之一。建立了一维地下水流与土体变形耦合数值模拟模型，并采用进化算法进行模型校正。计算的过去最大有效应力的时空变化表明，在粘土层的塑性固结的一部分，每年夏季的一部分，导致长期和渐进的地面沉降相同的地下水位波动范围。结果还表明，在干旱年份，全新世和更新世沉积物都发生了塑性变形，导致显著的沉降。除了2011年东北大地震后出现了结构性预测误差外，该模型的预测性能显示出良好的潜力。情景分析表明，夏季地下水位管理是抑制季节性地下水位波动引起地面沉降的有效对策之一。这些方法和研究结果可用于世界各地类似情况下的地下水管理。为了进一步改进所开发的模型，有必要对变形条件下大地震的影响进行额外的研究。
The causes of land subsidence in Kawajima, Japan, have been investigated through data compilation and numerical modeling. Land subsidence has progressed despite a gradual increase in the hydraulic head in the long term. Taking into account the temporal changes and depth distribution of groundwater abstractions, the contraction of formations, and the complexity of the hydrogeological structures, it is proposed that agricultural groundwater use is one of the main triggers for land subsidence. A one-dimensional numerical simulator for coupled groundwater flow and soil deformation was developed with an evolutionary algorithm for model calibration. The calculated spatiotemporal changes in the past-maximum effective stress showed that plastic consolidation in the clayey layers progressed part by part every summer season resulting in long-term and gradual land subsidence under the same range of groundwater level fluctuations. The results also showed that the plastic deformation occurred in both the Holocene and Pleistocene sediments in the drought years, leading to significant subsidence. The model’s predictive performance showed good potential except for a structural prediction error after the Tohoku Earthquake in 2011. The scenario analysis indicated that management of the groundwater level in summer is one of the effective countermeasures in suppressing land subsidence caused by seasonal groundwater level fluctuations. These methodologies and findings can be used for groundwater management in similar cases around the world. Additional investigation is necessary on the influence of large earthquakes in deformation conditions in order to further improve the developed model.