Describing coseismic groundwater level rise using tank model in volcanic aquifers, Kumamoto, southern Japan
Describing coseismic groundwater level rise using tank model in volcanic aquifers, Kumamoto, southern Japan
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DOI：
10.1016/j.jhydrol.2019.124464
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发表时间：
2020-03-01
影响因子：
6.4
通讯作者：
Shimada, Jun
中科院分区：
文献类型：
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作者：
Kagabu, Makoto;Ide, Kiyoshi;Shimada, Jun
为了说明熊本地区水位上升的存在性、强度和可能的机制，使用简单的概念性水文模型对2016年熊本地震后的地下水位变化进行了评估。应用水箱模型对研究区的16口威尔斯井进行了验证。在该模型中，地下水位首先被校准的时期约。利用降水量、蒸散量、补排水量和人工灌溉补给量等水文参数，对主震前2年的降雨量进行了模拟。然后，通过外推这种规律的水波动模式，模拟水位约。2.5年后主震的地震，而不考虑水文地质变化，由于地震。观测结果和模拟结果之间的地下水位差异产生了一定程度的同震水位上升，为每口井。主震后4-5个月内，同震水位异常升高约11 m，在阿索破火山口边缘山西坡最为显著。同震水增加的空间分布澄清，最占主导地位的增加异常盛行在山脚周围的平原，这表明发生同震山区水释放，导致在下坡含水层的水位上升。已确定的同震水位上升在地震后2.5年仍在继续，这可能是因为山区含水层的水文地质性质发生了变化，渗透性，仍然持续。我们预测水回收趋势需要CA。震后3.5-5年完全恢复原状。我们证明了我们的方法能够描述同震水位变化，并可能被应用到其他领域。
The change of groundwater levels after the 2016 M-w 7.0 Kumamoto crustal earthquake was evaluated using a simple conceptual hydrological model in an attempt to show the presence, intensity, and probable mechanism of water level rise observed in Kumamoto where a comprehensive observation-well network exists. A tank model was applied to verify 16 wells in the study field. In the model groundwater levels were first calibrated for the periods in ca. 2 years before the main shock using several hydrological parameters including precipitation, evapotranspiration, water recharge and discharge, and artificial recharge by irrigation. Water levels were then simulated by extrapolating this law of water fluctuating patterns for ca. 2.5 years after the main shock of the earthquake, without considering hydrogeological changes due to the earthquake. A difference in groundwater levels between observation and simulation results yields a degree of coseismic water level rises for each well. The coseismic abnormal water level increase was calculated to be similar to 11 m in 4-5 month after the main shock and was most significantly on the western slope of the Aso caldera rim mountains. The spatial distribution of the coseismic water increases clarified that the most dominate increasing anomalies prevail at mountain feet surrounding the plains, suggesting the occurrence of coseismic mountain water release resulting in the rise of water levels in downslope aquifers. Identified coseismic water level increases still continue up to 2.5 years after the earthquake, probably because changes in hydrogeological properties in mountain aquifers, i.e., permeability, are still sustained. Our forecasting water recovering trends require ca. 3.5-5 year after the earthquake for complete recovery to the original conditions. We demonstrated that our approaches are capable of describing coseismic water level changes and could potentially be applied to other fields.