Field study on mechanism of topography variation of bottom surface of tidal flat in which benthos are living in lagoon

1.影响加莫湖主潮滩底地貌的地形因素有：泻湖与河流分流的封闭杆、封闭杆上的开口、混凝土护岸、泻湖局部收缩或扩大宽度。2.主潮滩底面外观有两种情况：一是不平整，二是不平整。主潮滩附近测点的日最大流入流速和最大流出流速分别为0.6m/S和0.5m/s。4.主潮滩底高一年变化幅度为5~10 cm。冬季，底面高度一年上升，另一年下降，三年春季至7月均呈上升趋势。大潮时变化最大。5.主潮滩底质为砂质。中径为0.3 mm。根据Hjulstrom曲线，侵蚀速度为0.12m/s。6.冲刷速度超过冲刷速度的时刻较多，但底面高度没有变化。7.底栖动物对底面高度变化的影响不明显。

1.Topographical factors having effects on bottom topography of main tidal flat in Gamo lagoon are closing lever which separate lagoon and river, opening in closing lever, concrete-made revetment, and part of contraction or enlargement of width in lagoon.2.The appearance of bottom surface of main tidal flat are two cases : first is not uneven and smooth, second is uneven. Most days in a year, bottom height of a half in main tidal flat is high and a little uneven, and bottom height of the rest is lower and more uneven.3.Maximum inflow velocity and Maximum outflow velocity in a day at a measuring point near main tidal flat is respectively 0.6m/s and 0.5m/s.4.Variation of height of bottom surface in main tidal flat in a year is 5 to 10cm. Toward winter, height of bottom surface rises in one year, and drops in other year.It rises from spring to July all of the three years. and it seems mostly to change at flood in spring tide.5.Bottom sediments in main tidal flat is sandy. Medium diameter is 0.3mm. Following Hjulstrom's diagram erosion velocity is 0.12m/s.6.There are many moments exceeding erosion velocity, but variation of height of bottom surface do not occur. It seems to occur at flood when low water is high.7.Effect of benthos on variation of height of bottom surface is not evident.