(I am very new to statistics and in my first year of undergrad. So I am extremely sorry if my questions sound dumb but please bear with me).
Basically I want to find out whether upstream rainfall affects downstream flood extent.
Q1 Can I do this using cross-correlation? I wanted to use cross-correlation because I think that upstream rainfall will have an impact but after a few days (lag period)
Q2 How should I treat my data before performing cross-correlation?
Q3 Do I have to have the same number of data points in both time-series for cross correlation? (For example, I have rainfall data for 30 days. But I have flood extent data for only 7 days. So do I need to create a third time series comprising of the same days for which I have flood extent data? Or can I perform cross-correlation on the 30 day time series and the 7 day time-series?)
I would also appreciate if anyone could point me toward some resources on cross-correlation. Any help or advice will be HIGHLY appreciated. Kind of walking in the dark right now.