I am attempting to conduct an analysis of a Time Series for a given set of data that describes the monthly water levels in a water body, measured at the start of each month. My first step of the analysis is to describe the data I have plotted:
My question is - Given this example plot, what are the best terminologies that I can use to describe the trends within the data? For example, the most obvious feature of this graph is the dip from circa 2005 to 2010. How can I describe this in apt statistical language?