| dc.description.abstract | River plumes play a crucial role at the river-ocean interface, serving not only as a site for
the exchange of seawater and freshwater but also as a habitat for numerous organisms and the
first line of defense against riverine pollutants entering the ocean. The dynamics and extent of
river plumes are influenced by various factors, and there is currently no fixed standard for their
delineation. Water quality variation is an important indicator for studying changes in river
plumes. This study utilizes multi-satellite observations to analyze estuarine water quality in four
rivers in Taiwan: the Danshui River, Lanyang River, Gaoping River, and Beinan River, aiming
to gain a deeper understanding of plume dynamics. Apparent Visible Wavelength (AVW), an
index based on remote sensing reflectance calculations, is used to represent changes in water
color, combined with five different water quality indices including chlorophyll concentration,
diffuse attenuation coefficient, colored dissolved organic matter, total suspended solids, and
Secchi disk depth. By integrating data from multi-satellite observations from 1998 to 2023 and
using monthly average data and Empirical Orthogonal Function (EOF) analysis, the study
discusses the spatiotemporal variations in water quality in estuarine regions. The findings
indicate that the river plume from the Danshui River primarily disperses towards the southwest
of the estuary, while the Lanyang River disperses towards the southeast, the Gaoping River
towards the northwest, and the Beinan River disperses on both sides of the estuary. The
correlation between water quality indices and AVW is most significant in the Gaoping River
area, with Total Suspended Matter (TSM) showing the strongest correlation with AVW across
all estuaries, exceeding 0.5. Additionally, the study examines the use of AVW thresholds at 500
nm, 520 nm, and 525 nm for delineating river plume extents. Although 520 nm is suitable, it
does not form a closed area with the land, whereas 525 nm does form a closed area with the
land in most cases, making it the most appropriate AVW threshold for delineating the extent of
river plumes | en_US |