I have continuous (every 15 minutes) water level data from a tidal creek. I am no hydrographer. I am basing this on a method in K. Ellis et al (2017 Journal of South Carolina Water Resources). I am trying to process my tidal creek data to obtain accurate discharge. I deployed an instrument to measure discharge over a week and I have a rating curve that I can only use on HWS-normalized data.
I need to normalize time to high-water slack (HWS), which means detect the (max) high water mark every 9-14 hours (the tidal cycle time varies with wind).
What I was trying to do with Matlab give the initial high-water slack (HWS), because my water level data doesn't start at a peak, and then tell Matlab to find the next HWS 7-14 hours later (samples are every 15 minutes), so starting at 28 and ending at 56 cells after the last HWS index and I don't know how to do a moving window based on moving index of (max).
Ultimately, I need to make a new column of normalized time: time 0 (at high water), +0.25hrs, cum +0.25hr for each time step until the next HW (or 0)
There are 2 high waters and 2 high waters per lunar day- not a 24 hour cycle. Also of note… My average tidal cycle was 12.375 hrs… so 50 measurements
Sometimes the cycles are hard to detect, if there is a strong wind blowing the water out or keeping the water in. So I go with the 12.5 hour cycle as the default there.
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