Field observations and assessment of riverine geomorphologicalenvironments in view of integrated floodplain management

本文主要研究河道漫滩地下水位随枯水渠水位变化而发生的波动。乌吉河43.0公里站附近的滩地布设了垂直于低航道岸边的观测井阵列。观测到的地下水位快速上升和缓慢下降的表现清楚地反映了与台风和暴雨有关的洪水阶段的反应。仔细的时间序列分析确定了上升期的横向入渗和下降期的垂直入渗。计算出滩涂土壤在上升期和下降期的表观渗透系数分别为1.6×10-2~1.32 cm/S和1.9~3.4×10-4 cm/S。下降期的剩余地下水位与岸坡侵蚀过程密切相关。讨论了如何确定对未来河流管理的实际影响。

This study focuses on the unconfined groundwater table fluctuations in a floodplain of river channel that occur in response to water level changes of the low channel. The array of observation wells normal to the low channel bank was set up at the floodplain near the 43.0km station of Uji River. The observed performance of a rapid rise and slow fall in the groundwater table clearly captured the response to a flood stage associated with a typhoon and heavy rainfall. Careful time-series analyses identified lateral infiltration during the rising period and vertical infiltration during the falling period. The apparent coefficients of permeability in floodplain soil during the rising and falling period were calculated as equal to 1.6×10-2~1.32 cm/s and 1.9~3.4×10-4 cm/s, respectively. The residual groundwater table during the falling period closely related to a process of bank erosion. A discussion is made to identifying practical implications for future river management.