86 
eation is based on hydrodynamics and not bathymetry, the depth of the pycnocline 
and hence the boundaries of the designated uses changes on a monthly basis. 
DETERMINATION OF THE VERTICAL DENSITY PROFILE 
The vertical water column density profile (sigma-t) is calculated using the following 
equations: 
Sigma_t = tsum+((sigo+0.1324)*( l-sa+sb*(sigo -0.1324))) 
Where: 
tempc = water temperature in degrees Celsius 
salinity = salinity in grams per liter 
sigo = -0.069+(( 1.47808*((salinity - 0.03)/1.805))(0.00157* 
(((salinityBO.03 )/l.805 )**2))+0.0000398* 
(((salinityB0.03)/l .805)**3))); 
tsum = (-l*(((tempc - 3.98)**2)/503.57))* ((tempc+283)/(tempc+67.26)); 
sa = (10**-3)*tempc)*(4.7867 - (0.098185*tempc)+(0.0010843* 
(tempc**2))), 
and 
sb = ((10**-6)*tempc)*( 18.030-(0.8164*tempc)+(0.01667*(tempc**2))). 
DETERMINATION OF THE PYCNOCLINE DEPTHS 
To determine the depths of the pycnocline, the following rules are applied to the 
density profile: 
1) From the water surface downward, the first density slope observation that is 
greater than 0.1 kgnr 4 is designated as the upper pycnocline depth provided that: 
a) that observation is not the first observation in the water column; and 
b) the next density slope observation below is positive. 
2) From the bottom sediment-water interface upward, the first density slope obser¬ 
vation that is greater than 0.2 kg nr 4 is designated as the lower pycnocline depth 
provided that: 
a) an upper pycnocline depth exists; 
b) there is a bottom mixed layer, defined by the first or second density 
slope observation from the bottom sediment-water interface being less 
than 0.2 kg m' 4 ; and 
c) the next density slope observation above is positive. 
chapter vii 
Upper and Lower Pycnocline Boundary Delineation Methodology 
