80 
1.5 root Turb 
system -Chickahominy — James Lynnhaven 
-Mattaponi Piankatank Pumunkey 
York 
Figure VII-9. Simple linear regression of predicted K d versus the 1.5 root of measured 
turbidity using shallow water monitoring data from seven Virginia tidal tributaries 
(2003-2005). 
Source: Virginia Institute of Marine Science—www2.vims.edu/vecos. 
coefficients and intercepts occur to form groupings of tributary data for calibration 
purposes. The groupings developed to date reflect a strong geographic pattern, which 
strengthens their validity. 
INTERPOLATION 
The very dense in situ measurements of turbidity from each sampling cruise track 
(Figure VII-10) are first converted to K d . The natural log of the converted K d values 
are then interpolated using a standardized ordinary kriging procedure with ARC/GIS 
into a 25-meter square grid over the segment’s entire surface area. Once interpo¬ 
lated, the resultant interpolated K d values are transformed back. Each interpolator 
cell within a segment’s shallow-water area is then assessed against a specific K d 
value for each applicable water clarity criterion application depth. An interpolator 
cell value equal to or below this K d value is considered in attainment of the appli¬ 
cable water clarity criterion. A number above this value has failed to meet the 
applicable water clarity criterion. 
The entire area within the shallow-water designated-use zone for each sampling 
cruise is then aggregated on an interpolator cell-by-cell basis to determine the total 
area either in attainment or failing to meet the applicable water clarity criterion. 
Water clarity attainment acres are determined for the total area within the shallow- 
water area of each segment from the shoreline out to the 2-meter depth contour 
excluding the delineated SAV no-grow zones (see Chapter 5 for details). 
chapter vii 
Shallow water Monitoring and Application for Criteria Assessment 
