Browsing by Author "Yoshihisa Shimizu"

Now showing 1 - 3 of 3
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    Application of artificial intelligence methods for monsoonal river classification in Selangor river basin, Malaysia
    (Springer, 2021) Yong Jie Wong; Yoshihisa Shimizu; Akinori Kamiya; Luksanaree Maneechot; Khagendra Pralhad Bharambe; Chng Saun Fong; Nik Meriam Nik Sulaiman
    Due to its tropical climate, the impact of seasonal monsoons on river quality is significant, with the increased occurrence of extreme precipitation events; however, there has been little discussion on the application of artificial intelligence models for monsoonal river classification. In light of these, this study had applied artificial neural network (ANN) and support vector machine (SVM) models for monsoonal (dry and wet seasons) river classification using three of the water quality parameters to minimise the cost of river monitoring and associated errors in WQI computation.
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    Comparison among different ASEAN water quality indices for the assessment of the spatial variation of surface water quality in the Selangor river basin, Malaysia
    (Springer, 2020) Yong Jie Wong; Yoshihisa Shimizu; Kai He; Nik Meriam Nik Sulaiman
    The assessment of surface water quality is often laborious, expensive and tedious, as well as impractical, especially for the developing and middle-income countries in the ASEAN region. The application of the water quality index (WQI), which depends on several independent key parameters, has great potential and is a useful tool in this region. Therefore, this study aims to find out the spatial variability of various water quality parameters in geographical information system (GIS) environment and perform a comparative study among the ASEAN WQI systems.
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    Verifying the applicability of SWAT to simulate fecal contamination for watershed management of Selangor River, Malaysia
    (Elsevier, 2021) Takashi Kondo; Nobumitsu Sakai; Taishi Yazawa; Yoshihisa Shimizu
    The Soil and Water Assessment Tool (SWAT) ecohydrological model was utilized to simulate fecal contamination in the 1937 km2 Selangor River Watershed in Malaysia. The watershed conditions posed considerable challenges owing to data scarcity and tropical climate conditions, which are very different from the original conditions that SWAT was developed and tested for. Insufficient data were compensated by publicly available data (e.g., land cover, soil, and weather) to run SWAT. In addition, field monitoring and interviews clarified representative situations of pollution sources and loads, which were used as input for the model. Model parameters determined by empirical analyses in the USA (e.g., surface runoff, evapotranspiration, and temperature adjustment for bacteria die-off) are thoroughly discussed. In particular, due consideration was given to tropical climate characteristics such as intense rainfall, high potential evapotranspiration, and high temperatures throughout the year.