APPLICATION OF REMOTE SENSING FOR ADJUSTMENT AND CALIBRATION OF WATER QUALITY MODEL - Integrating GIS, Remote Sensing, and Mathematical Modelling for Surface Water Quality Management - page 184

Figure (8-33): CHL-a map of the lake region (including vegetation and fisheries areas). For Colour scheme see
Figure (8-34)
Figure (8-34): Extracted CHL-a pixels inside the lake water body
8.6.4. Calibration of CHL-a Model Using SPOT-Based Concentration Maps
The calibration of the CHL-a model was done based on adjusting the algal species to nutrients ratios.
Due to the spatially limited number of measured CHL-a samples in the lake and the lack of any
historical measurements of CHL-a there was a need to use data from the remote sensing images it the
calibration process. The model calibration was done based on adjusting the nutrients inputs to develop
a CHL-a map with concentrations close to the images extracted concentrations. Several runs were
carried out by adjusting the nutrients inputs until the concentrations of CHL-a became close to the
extracted values from the SPOT image. Figure (8-35) shows the CHL-a model results prior to
calibration procedures.
Figure (8-35): CHL-a model concentrations (July 10 th) , 2006
The first step in the calibration of the CHL-a model is to test the spatial variation between the model
and the image maps. Two sections were taken along the flow paths shown in Figure (8-36) to illustrate
the spatial variation in the concentrations along the northern area of the lake region free of submerged