  Floods of research and practical applications employ social media data for a
wide range of public applications, including environmental monitoring, water
resource managing, disaster and emergency response.Hydroinformatics can benefit
from the social media technologies with newly emerged data, techniques and
analytical tools to handle large datasets, from which creative ideas and new
values could be mined.This paper first proposes a 4W (What, Why, When, hoW)
model and a methodological structure to better understand and represent the
application of social media to hydroinformatics, then provides an overview of
academic research of applying social media to hydroinformatics such as water
environment, water resources, flood, drought and water Scarcity management. At
last,some advanced topics and suggestions of water related social media
applications from data collection, data quality management, fake news
detection, privacy issues, algorithms and platforms was present to
hydroinformatics managers and researchers based on previous discussion.
