Consequences of the river valley bottom transformation after extreme flood (on the example of the Niida River, Japan)
Consequences of the river valley bottom transformation after extreme flood (on the example of the Niida River, Japan)
复制标题
特大洪水后河谷底部改造的后果（以日本新田川为例）
DOI：
10.1088/1755-1315/107/1/012002
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
Wakiyama Y
中科院分区：
文献类型：
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作者：
Botavin D;Golosov V;Konoplev A;Wakiyama Y
在2015年9月中旬发生的极端洪水事件后，对新伊达河流域（福岛县）不同部分的洪泛区进行了详细研究。该流域的上游部分位于福岛第一核电站事故后放射性核素污染水平非常高的区域。现场和地理信息系统的方法，包括直接测量新鲜沉积物的深度及其面积，土壤描述的典型洪泛区部分，剂量率的测量，空间图像的解释为几个时间间隔（洪水事件之前和之后）与以下的空间变化的沉积不同洪泛区部分的评价。此外，还利用沉积速率和土壤放射性核素污染的定量评估结果，了解极端洪水对不同地段冲积土的影响。结果表明，最大沉积速率（20-50 cm/次）出现在Niida河下游的中部和上游的某些位置。所有高沉积地区的剂量率都大大降低，因为具有高放射性核素污染的表层土壤被埋在主要由河岸侵蚀和质量运动产生的新鲜沉积物之下。
Detailed study of different sections of floodplain was undertaken in the Niida River basin (Fukushima Prefecture) after an extreme flood event which occurred in the middle of September 2015. The upstream part of the basin is located in the area with very high level of radionuclide contamination after the accident at Fukushima Dai-ichi NPP. Field and GIS methods were used, including direct measurement of the depth of fresh sediment and its area, with soil descriptions for the typical floodplain sections, measurement of dose rates, interpretation of space images for a few time intervals (before and after flood event) with the following evaluation of spatial changes in deposition for different floodplain sections. In addition, results of quantitative assessment of sedimentation rates and soil radionuclide contamination were applied for understanding the effect of extreme flood on alluvial soils of the different sections. It was established that the maximum sedimentation rates (20-50 cm/event) occurred in the middle part of the lower reach of the Niida River and in some locations of the upper reaches. Dose rates had reduced considerably for all the areas with high sedimentation because the top soil layers with high radionuclide contamination were buried under fresh sediments produced mostly due to bank erosion and mass movements.