Publications

Breunig, FM; Pereira, W; Galvao, LS; Wachholz, F (2016). Assessing the Long-Term Variability of TSS and Chlorophyll in Subtropical Reservoirs Using MODIS Data. IEEE JOURNAL OF SELECTED TOPICS IN APPLIED EARTH OBSERVATIONS AND REMOTE SENSING, 9(12), 5406-5412.

Abstract
The remote sensing assessment of the long-term variability in optically active constituents of the waters is very important to understand the dynamics of the reservoirs at temporal and spatial scales. We evaluated variations over time (2000-2015) in total suspended solids (TSS) and chlorophyll-a concentrations in the Passo Real reservoir, located in south Brazil. For this purpose, we tested two MODIS composite products: MOD09A1 and MCD43A4. Regression relationships of the red (TSS) and green (chlorophyll-a) reflectance of these products with limnological data of 12 field campaigns were obtained and compared to estimate these constituents on a per-pixel basis. Three major sections of the reservoir (upper, middle, and lower sections) were selected in the analysis. The results showed that the MODIS MCD43A4 (corrected for bidirectional effects) produced better estimates of TSS and chlorophyll-a than the MOD09A1 product. The highest concentrations of TSS were observed from September to October with the concomitant increase in precipitation and the predominance of exposed soils. The peak of TSS concentration between these two months was closely followed by another peak of chlorophyll-a content. It occurs probably because of the higher nutrient availability with sediment loading, the intensive land use with crop development, and the increase in water temperatures. Differences over time between the peaks of TSS and chlorophyll-a varied from the upper (two-month shift) to the lower (one-month shift) sections of the reservoir. They were associated with the different stream inflows and the residence time of the waters.

DOI:
10.1109/JSTARS.2016.2589820

ISSN:
1939-1404