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 174

70

y = 4.0176e 32.107x
R² = 0.8524

60

50

40

30

20

0.06 0.065 0.07 0.075 0.08 0.085

Reflectance of MODIS band 1

Figure (8-15): The relationship between the measured TSM concentration and the surface reflectance
at band1 (665nm)

8.5.2. Selection of Region of Interest (ROI) Using SPOT High Resolution Scene

Due to the low resolution of the MODIS images which results in mixed pixels of water and vegetation
even in open water areas, there was a need to define a specific region of interest (ROI) within the lake
water body assuming the least possible mixing effect. This was done using the SPOT image with a
resolution of 10m, where the region of interest was selected based on the free water pixels, and this
area was up-scaled to the MODIS image. Figure (8-16) shows the original SPOT image of resolution
10m showing the detailed parts of the water body. The SPOT image and the defined regions of interest
(ROI's) are shown in Figure (8-17) . This selected ROI was used in all the comparisons of the detailed
TSM model results and the image-based concentration maps.

Figure (8-16): SPOT image of resolution 10 meters showing detailed components of the lake system

Figure (8-17): SPOT image and selected regions of interest (ROI) within the main lake water body