| Abstrak/Abstract |
The rapid development of remote sensing technology has increased possibility to produce spatially explicit estimation of Total Suspended Solids (TSS). However, definite information regarding the effective depth of waters where TSS can be effectively mapped using remote sensing data is rare. This information is important to determine the effective depth of TSS mapping and the effect of the water column on the representativeness of the estimation results. This research is aimed to (1) determine the effective water depths of TSS mapping using PlanetScope imagery, (2) map the spatial distribution of TSS at every effective depth using PlanetScope imagery, and (3) analyze the spatial distribution of the mapped TSS based on the best empirical modeling for every effective depth. In total, there were four single bands of PlanetScope image (blue, green, red, and near-infrared)—corrected to the Bottom of Atmosphere (BOA) reflectance, 12 band ratios, and four Principle Component bands (PC-band) inputted to the determination process of the effective water depths. This research investigated the correlation between TSS at each water depth and the twelve images derived from PlanetScope image. Empirical modeling between PlanetScope image and the field TSS at each effective water depth was conducted for single bands, band ratios, and PC-band that exceeded the significance limit (r) and employed linear, exponential, logarithmic, second-order polynomial, and power regressions. The results showed that through a band ratio, PlanetScope images could record TSS up to the effective depth of 1.8 m but showed no responses deeper than this point. The best empirical modeling in each effective depth of waters was the band ratio which is dominated by the contribution of the blue bands (B1), red (B3), and NIR (B4). B4/B3 bands combination produced TSS information at the effective depths of 0-0.2 and 0-0.4 m, B3/B4 bands at 0-0.6 and 0-0.8 m, B1/B4 bands at 0-1 and 0-1.2 m, and B1/B3 bands at 0-1.4, 0-1.61, and 0-1.8 m. For all effective depths, the spatial distribution pattern of TSS in the study site (Menjer Lake, Central Java, Indonesia) showed that high concentrations evenly spread along the edge and became increasingly lower to the center of the lake. Meanwhile, the vertical distribution showed that the deeper the cumulative water depth, the higher the TSS. |
