Hydrological modelling of a slope covered with shallow pyroclastic deposits from field monitoring data
Hydrological modelling of a slope covered with shallow pyroclastic deposits from field monitoring data
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DOI：
10.5194/hess-17-4001-2013
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发表时间：
2013-01-01
影响因子：
6.3
通讯作者：
Picarelli, L.
中科院分区：
文献类型：
--
作者：
Greco, R.;Comegna, L.;Picarelli, L.
建立了一个覆盖火山碎屑物质的一维坡面水文模型。土壤覆盖层由松散的火山灰和浮石层组成，总厚度在1.8 m和2.5 m之间，位于破碎的石灰岩基岩上。斜坡的平均倾角约为40度，略大于灰烬的摩擦角。因此，平衡的斜坡，显着影响的粘性贡献所施加的土壤吸力在非饱和条件下，可能会改变降雨入渗。该模型假设一个单一的均匀的土壤层占据整个深度的覆盖，并考虑到季节性变化的冠层截留的降水和根系吸水的植被，主要是由落叶板栗林与茂密的灌木丛生长在春末和夏季。底部边界条件将土壤-基岩界面处的水势与位于裂缝石灰岩中的含水层的水位波动联系起来，裂缝石灰岩在概念上被建模为线性水库。大部分的模型参数已被指定根据文献的指示或从实验数据。2011年1月1日至2011年7月20日期间，在沿着斜坡安装的监测站测量的土壤吸力和含水量数据允许确定其余参数。校准的模型，再现非常密切的校准集的数据，已被施加到模拟的水文响应的斜坡的每小时降水记录的1999年，当一个大的流状滑坡被触发接近监测位置。模拟结果表明，有史以来最低的土壤吸力发生在滑坡被触发时，这表明该模型是能够预测边坡的破坏条件。
A one-dimensional hydrological model of a slope covered with pyroclastic materials is proposed. The soil cover is constituted by layers of loose volcanic ashes and pumices, with a total thickness between 1.8 m and 2.5 m, lying upon a fractured limestone bedrock. The mean inclination of the slope is around 40 degrees, slightly larger than the friction angle of the ashes. Thus, the equilibrium of the slope, significantly affected by the cohesive contribution exerted by soil suction in unsaturated conditions, may be altered by rainfall infiltration. The model assumes a single homogeneous soil layer occupying the entire depth of the cover, and takes into account seasonally variable canopy interception of precipitation and root water uptake by vegetation, mainly constituted by deciduous chestnut woods with a dense underbrush growing during late spring and summer. The bottom boundary condition links water potential at the soil-bedrock interface with the fluctuations of the water table of the aquifer located in the fractured limestone, which is conceptually modelled as a linear reservoir. Most of the model parameters have been assigned according to literature indications or from experimental data. Soil suction and water content data measured between 1 January 2011 and 20 July 2011 at a monitoring station installed along the slope allowed the remaining parameters to be identified. The calibrated model, which reproduced very closely the data of the calibration set, has been applied to the simulation of the hydrological response of the slope to the hourly precipitation record of 1999, when a large flow-like landslide was triggered close to the monitored location. The simulation results show that the lowest soil suction ever attained occurred just at the time the landslide was triggered, indicating that the model is capable of predicting slope failure conditions.