Originally Posted by carvedog
Someone posted up about a mythical 1.1 trip they were on and I did a bit of research around that a while back looking for that low of flow but could not find. Sounds like Shap did too.
It did get down to about 1.1 feet in 1977 as well as pretty close in 2001 (1.17 feet) using the current stage-discharge relationship (i.e. how many feet on the gage = what flow in cfs).
Also on average (i.e. mean) vs median. Average is the sum of values divided by the number of values.
Median is the value that is smack dab in the middle of a range of values when lined up lowest to highest.
for example, lets say daily flow values for some period of interest are
500, 500, 600, 700, 3000.
The median value is 600, the average is 1060 (nearly double the median), but probability wise, if you randomly picked one of these values, on average you would pic a value 4 out of 5 times that was close to 600 cfs, only a 1 in 5 chance of picking the value a lot higher than 600 cfs.
Averages can be highly screwed up or down based on extreme outlier values. Averages don't work well for examining stream flows to determine what you might expect in the future based on what the distribution of values were in the past, especially when looking at flows in the higher ranges cause floods really screw things up and cause huge outliers. For low water season, averages tend to be a lot close to median values because the range between really low flows and really high flows during the "low" water season is a lot less compared to the range of values that might occur during the medium or high water season.
Bottom line, best to look at median value if you are looking at what to expect "on average" to occur during any particular boating month or season.