|
Water clarity influences a variety of stream characteristics.
A measure of water clarity is important as an indicator of many
different processes at work in the system. The simplest method
of measuring water clarity is a secchi disk. While a secchi disk
is typically used to measure water transparency in large, deep
water-bodies, it can be used to measure water clarity in streams.
The exception to this is in shallow, fast running streams. A
secchi disk is a 20cm disk with black and white quadrants. For
stream work, the disk is attached to a wooden calibrated rod.
The secchi depth measurements described below are read from calibrated
marks on the rod. Field instructions: 1. Lower the disk into the water until it disappears from view and record this depth. 2. Drop the disc several cm more. 3. Slowly pull the disk back up and record the depth at which it reappears. 4. Calculate the secchi depth by averaging these two measured depths. |
 |