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The main purpose of this study is to develop a water quality
simulation model of river in order to aid the decision maker in
water quality simulation of strategies planning of water
pollution control. Moreover, this study also identify various
water quality impact of point and nonpoint sources on river by
the use of the water quality simulation model. The pollution
sources considered includes point and nonpoint sources in the
water quality simulation model. The component of river basin
system considered includes branches, tributaries, tidal and non-
tidal areas. The river system is assumed to be an one
dimensional steady state system. The water quality parameters
are simulated includes DO, BOD, T-N, and T-P with an assumption
of first order decay of BOD,T-N and T-P. What are to be
discussed in the case study of Chung-Gung River results have
shown that : (1)it is required to consider nonpoint sources in
the planning of water quality control strategy; (2)the loading
of point source is fixed, the water quality impact will be
added when the non-point sources discharge into the river. The
water quality impact will become larger when the loading is
larger; (3)the loading of point source is more larger then the
water quality impact of varies loadings of nonpoint sources is
vary small. But the water quality impact of nonpoint sources
will be vary large when the loading of point source is small.
So that the control of nonpoint sources is becoming a major
challenge to water quality manager when the most point source
pollution have been controlled; (4)in general, the water
quality impact of distributed discharges will be reduced,
nonpoint sources almost get into the river with distributed
discharge. However, this study consider the nonpoint sources as
most sever, so that the real water quality of river seems to be
much better than the simulation results; (5)at various base
flow, the water quality impact of nonpoint sources on river
will be reduced when base flow become lager.
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