Author/Authors :
Jeong، K S نويسنده Department of Biological Sciences, Pusan National University , , Kim، D K نويسنده School of Computer Science & Engineering, Seoul National University , , Shin، H S نويسنده School of Civil and Environmental Engineering, Pusan National University , , Kim، H W نويسنده Department of Environmental Education, Sunchon National University , , Cao، H نويسنده School of Earth and Environmental Sciences, University of Adelaide , , Jang، M H نويسنده Department of Biological Education, Kongju National University , , Joo، G J نويسنده Department of Biological Sciences, Pusan National University ,
Abstract :
In this study a machine learning algorithm was applied in order to develop a predictive model
for the changes in phytoplankton biomass (chlorophyll a) in the lower Nakdong River, South Korea. We used
a “Hybrid Evolutionary Algorithm (HEA)” which generated model consists of three functions ‘IF-THENELSE’
on the basis of a 15-year, weekly monitored ecological database. We used the average monthly data, 12
years for the training and development of the rule-set model, and the remaining three years of data were used
to validate the model performance. Seven hydrological parameters (rainfall, discharge from four multi-purpose
dams, the summed dam discharge, and river flow at the study site) were used in the modeling. The HEA
selected reasonable parameters among those 7 inputs and optimized the functions for the prediction of
phytoplankton biomass during training. The developed model provided accurate predictability on the changes
of chlorophyll a (determination coefficients for training data, 0.51; testing data, 0.54). Sensitivity analyses for
the model revealed negative relationship between dam discharge and changes in the chlorophyll a concentration.
While decreased dam discharge for the testing data was applied; the model returned increased chlorophyll a by
17-95%, and vice versa (a 3-18% decrease). The results indicate the importance of water flow regulation as
specific dam discharge is effective to chlorophyll a concentration in the lower Nakdong River.
