Water Quality Mapping Using Remote Sensing Imagery –Application to Fei-Tsui Reservoir
Date Issued
2009
Date
2009
Author(s)
Hsu, Shu-Mei
Abstract
Fei-Tsui Reservoir is the main source of water supply for the Taipei Metropolis. However, reservoir eutrophication has become a critical concern of the reservoir administration agency due to increasing anthropogenic activities in recent years. The Carlson trophic state index (CTSI) is widely used in Taiwan for monitoring of reservoir water quality. Unfortunately, misuse of CTSI, including averaging individual indices and without calibration for local conditions, has led to serious debates and confusions about the current state of the reservoir water quality. Thus, the objectives of this study are to modify the CTSI model considering the water quality characteristics of Fei-Tsui Reservoir, and to develop a remote sensing technique for reservoir trophic state evaluation. set of modified trophic state indices was developed for the Fei-Tsui Reservoir by considering empirical relationships among Chlorophyll-a concentration, total phosphorous concentration, and Secchi disk depth. Criteria for determining reservoir trophic state using these indices were also proposed. ultispectral images from the SPOT satellite were collected and used to develop algorithms for water quality estimation from radiances recorded by the SPOT satellite. Estimates of water quality based on remote sensing techniques are in good agreement with water quality measurements with correlation coefficients higher than 0.88. Images of water quality distribution derived from remote sensing techniques reveal that eutrophication only occurs in the upstream area and confluence of tributaries and the main channel, while water quality condition generally improves towards downstream. Generally speaking, trophic states of the Fei-Tsui Reservoir are oligotrophic or mesotrophic in recent years.
Subjects
Satellite Remote Sensing
Fei-Tsui Reservoir
Water Quality Monitoring
Eutrophication
Carlson Trophic State Index (CTSI).
SDGs
Type
thesis
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