About YAMADA YOSHIHIRO
About MITO YUGO
About irrigation
About river mouth barrier
About nitrogen
About phosphorus
About concentration(ratio)
About ponding
About watershed
About organic substance
About farm pond
About water pollution
About effect
About amount of precipitation
About water quality
About circulation
About seasonal variation
About Kagawa prefecture
About river pollution
About river water quality
About dilution effect
About matter cycle
About River pollution
About 灌漑
About 流域
About 河口堰
About 貯水
About 窒素
About リン