Annual precipitation Beijing-tianjin-hebei regions 1 China 1 Climatology 1 Ecosystems 1 Eutrophication 1 Field observation 1 Field observations 1 Flow variability 1 Great Lakes [North America] 1 Indicator indicator 1 Interannual 1 Lake Erie 1 Lakes 1 Long-term data 1 Monitoring 1 Normalisation 1 North China 1 Nutrient concentrations 1 Nutrients 1 Precipitation 1 Precipitation (chemical) 1 Rapid urbanizations 1 Regional climate 1 Rural areas 1 Statistics 1 Stream 1 Streams 1 Temperate climate 1 Temperate zone 1