poster - International Conference of Agricultural Engineering

topographic features and hydro-meteorological characteristics and to stably supply water
and effectively control flooding, water resources development projects have been carried
out.
Most recently, due to urbanization and industrialization, as well as population
pressures, the amounts of water usage have increased, and the states of water quality in
rivers have degraded. Thus, it has been requested to secure water resources
abundantly enough to upgrade the water-friendliness of rivers and rehabilitate the
environment and ecosystems. Also, due to the prevalence of irrigation farming, the
amount of agriculture water usage has increased. Besides, in rural areas, more water
needs to be supplied than in the past, because the population wants to enjoy their
prosperity under civilized circumstances. According to this information about water
resources, it is predicted that, in 2020, about 0.82 billion m 3 would be deficient in South
Korea.
To secure water resources under the aforementioned circumstances, structural
and non-structural measures are to be developed, and it is apparent that they need to go
into effect in the near future. Particularly, to maintain the environment and ecosystems
from the perspective of sustainability, non-structural measures, such as joint-operations of
multi-reservoir systems and water demand management, are to be determined and
implemented consistently. Moreover, due to the changes in climate, socio-economic
systems, and eco-systems, the operation rules of existing water resources facilities should
be reviewed and adapted to the changes. To achieve these management objectives,
tools for evaluating water supply capacities of systems, such as water-budget models,
simulation models, and optimization models, are to be prepared, and appropriate
scenarios are to be created to determine efficient operation rules for the systems (Yeh,
1985; Wurb, 1993).
In this study, an optimal reservoir operation model is developed through integration
of a nonlinear, multiple-objective function, a global optimization method, and a streamflow
network model, and it is then applied to simulating the operations of two study reservoirs
to verify the model’s applicability.
2. Optimal Reservoir Operation Model
In general, reservoir operation revenues are evaluated using simulation models,
optimization models, and simulation-optimization models (Dandy et al., 1997).
Particularly, simulation-optimization models have been employed to consider peculiar
objective functions and operation conditions of specific operation periods through using
simulation models and optimization models alternatively. Fig. 1 shows the flowchart of
the presented model, which is grouped into the simulation-optimization models category
and takes one of the simulation and optimization modules, taking into account the
condition of each operation period of reservoirs.
2.1 Reservoir Operation Sub-model
A reservoir operation sub-model is developed to compute reservoir storage amounts and
hydro-electric power outputs, considering inflows, releases, overflows during operation
periods. During the simulation, in the case that the quality assurance of the data
pertaining to observed inflows is confirmed, the historical inflow data is employed, and in
other cases, the inflow data is generated using the SSARR hydrologic model. The
amounts of municipal and industrial water usages and in-stream flow are determined
before reservoir operations, considering the demand of each. On the other hand,
agricultural water demands of all periods are simulated using the modified Penman
method, considering the situations of rice paddy fields. Hydro-electric power outputs of