miles or kilomiters
Miles.Miles.Miles.Miles.
feet
miles
A metres, for an approximate measure, a centimetre for a more accurate measure.
Centimeters.
Miles.Miles.Miles.Miles.
The basic metric unit for length is the metre. Rivers would be measure in kilometres (1,000s of metres)
The width of a river will generally be measured in feet or meters, depending on if you use Imperial or Metric.
By unit of length and distance and conversion ,we can say that the most appropriate unit to measure the length of a finger is cm.
Inches
cm
always the meter to measure length. This is an SI (international) unit of measurment, and is the standard international unit of measurment for length.
I would use feet
You would use meters.
yards
well if you have a small river less than a mile long you will probably want something like a kilometer or meter. But if it is a longer river you may want to use miles or kilometers (the metric system is shorter but easier to convert.)
feet