Table 2 Manning’s n values (suggested references from HEC-RAS Hydraulic Reference Manual 6.0 3-1)
From: Reconstructing Nanwang hub operations on Ming-Qing Grand Canal with HEC-RAS
Type of channel and description | Minimum | Normal | Maximum |
|---|---|---|---|
Cultivated areas | |||
a. No crop | 0.02 | 0.03 | 0.04 |
b. Mature row crops | 0.025 | 0.035 | 0.045 |
c. Mature field crops | 0.03 | 0.04 | 0.05 |
Earth, winding and sluggish | |||
a. No vegetation | 0.023 | 0.025 | 0.03 |
b. Grass, some weeds | 0.025 | 0.03 | 0.033 |
c. Dense weeds or aquatic plants in deep channels | 0.03 | 0.035 | 0.04 |
d. Earth bottom and rubble side | 0.028 | 0.03 | 0.035 |
e. Stony bottom and weedy banks | 0.025 | 0.035 | 0.04 |
f. Cobble bottom and clean sides | 0.03 | 0.04 | 0.05 |
