| Summary: | 博士 === 國立成功大學 === 環境工程學系 === 84 === ABSTRACT Feitsui Reservoir is applied to depict water quality
changes in thereservoirs of Taiwan area during incipient
operation peroid. Duringthe first few years of operation, not
only the water quality but also theaquatic ecosystem is in an
unstable status. The water quality of a newlyconstructed
reservoir may stabilize after 3-4 years of operation in
thenorthern region of Taiwan, but the trophic upsurge can
persist over 6 years. The rate of stabilization depends on
factors such as climate, basin morphometry, hydrology and
operation process of the reservoir etc. Mostreservoirs become
eutrophic or experience unstable water quality conditionsin the
first few years after their construction. Besides the
pollutedinflow, the decayed vegetation and distrubed topsoil of
flooded area wererecognized as two major nutrient sources
contribute to reservoir eutrophicationduring the incipient
operation period. The biomass of terrestrial vegetation and its
potential for nutrient release were surveyed for the area
flooded by the creation of the Nan-hua Reservoirin southern
Taiwan, a reservoir with tropical climate and broad leaf
evergreen forest vegetation. The fresh biomass of the flooded
vegetation was estimated at 48,641 kg/ha, with an equivalent dry
biomass of 15,540 kg/ha. Aftercomplete decay following
submergence, the flooded terrestrial vegetationcould potentially
contribute 6,700 kg of carbon, 238kg of nitrogen and 37 kg of
phosphorus per hectare to the overlaying water. Therefore, the
potential for nutrient release from the area of 655 ha, flooded
by the Nan-hua Reservoir (with water storage capacity of 157x106
m3) was estimated to be 4.388x106 kgof carbon, 158.6x103 kg of
nitrogen, and 24.2x103 kg of phosphorus. For thetopsoil
(0-10cm), the potential of nutrient contribution was estimated
at551x103 kg phosphorus and 541x103 kg nitrogen. Simulating
Nan-hua Reservoirpractical operation process, the nutrient loads
from inundated vegetation are 30896 kg nitrogen and 4322 kg
phosphorus during the first 17 months operation period.
According to mass balance calculation, the nutrient loads
fromflooded topsoil are 35098 kg nitrogen and 2528 kg phosphorus
from May, 1994to April, 1995.
|
|---|
