Due to the main stream top support action, N, P expressed possessing space distribution character of peak value.

The drainage pattern of the aquatic system is complex. In rocky area, the drainage of the top beds of the system makes up 59.2% of the total drainage.

B. a column bar (6) is firmly positioned with a lower joint-body of an upper buckling and pressing mechanism (1) and is propped by a top-suspending spring (12);