Continuous and periodic monitoring
Some instruments record measurements at short intervals, while other programs collect samples weekly, monthly, seasonally, or during targeted events such as storms. A continuous record and a periodic sample answer different questions.
Why gaps are normal
Equipment maintenance, unsafe conditions, missing samples, laboratory processing, and changes in program design can create gaps. A gap is a limitation to describe, not evidence that conditions stayed constant.
How to compare responsibly
Check the station, date range, unit, method, and sampling frequency before comparing two rivers or two seasons. Rivistry shows source and timing context so readers can see what a series does and does not represent.