Developaent of a successive flow monitoring system to elucidate the relationship of erosion, transportation and deposition of gravel controlled by flow-depth and velocity, and observation by the system.

1.为了揭示砾石的侵蚀、输移、沉积关系与水深、流速的关系，获得连续的水流资料，我们研制了Nortec AS EasyQ多普勒型二维监测流的河流监测系统，并对山形盆地的Midaregawa河进行了连续监测。2.2002年7 ~ 11月日本东北部发生了几次洪涝灾害，并对洪涝灾害数据进行了修正。在7月10日至11日的最大洪水中，由于台风6 Lh的影响，当流速超过2 m/s时，河床上的卵石开始移动，当流速达到2 m/s时，卵石沉积在位于河边沿着的监测系统上。Sm/s。最大流速估计超过3.5m/s。根据河床上砾石的结构，砾石似乎是跳跃着移动的，并平行于水流方向伸长。监测系统在高水淹阶段（流速大于2。Sm/a），在洪泛减弱阶段趋于平稳。当流速超过2.5m/s时，水流开始切割砾石河床，并在河岸边存款砾石，在最大洪水阶段，水流不断切割和沉积砾石，在洪水减弱阶段，水流开始侧向冲刷河岸边。

1.With a view to reveal the relationship between the relationship of erosion, transportation and deposition of gravel and the flow-depth and the flow-velocity, and to get continuous flow-data, we developed the River monitoring system by Nortec AS EasyQ doppler-type two dimensional monitoring stream, and made a continuous monitoring at the Midaregawa River in the Yamagata Basin, Northeast Japan.2.There were a several flooding during July to November in 2002 and we corrected the data of flooding. At the largest flooding in July 10 to 11, caused by Typhoon 6Lh, when the velocity of the stream exceeded 2m/s, pebbles on the river bed began to move, and deposited on the monitoring system which was located along the side of the river margin when the velocity reached to 2. Sm/s. The maximum speed of the flow was estimated to be more than 3.5m/s. The gravels seemed to move with saltation and with elongating parallel to the flow direction, according from the fabric of gravels on the river floor. The monitoring system had malfuncitoned during high flooding stage (velocity was more than 2. Sm/a), and then evened out at waning stage of flooding. This means that the flow begins to incise the gravel river bed and deposit the gravels on the river margin when the velocity of the stream exceeds 2.5m/s, and is incising and depositing continuously during maximum flooding stage, then begins to erode laterally river margin at the stage of waning stage.