In geology, how we look at systems depends on different scales of space and time. Bloschl (1999) defines a scale as a characteristic length or time. Length scales are centimeters, meters, and kilometers; time scales are seconds, minutes, hours, days, years, etc. A process may vary depending on the time and space scale (the lense) we are looking it.
Bloschl (1999) breaks down sampling into 3 components which are useful to think about when planning a study:
- support (how much space or time each measurement encompasses)
- extent (the total amount of space or time that is monitored)
- spacing (the space or time between measurements)
These considerations are important. Usually, we want to increase support (have each measurement average some space and time) and decrease spacing (more measurement). Depending on the extent of the measurements, you might learn something different about the system. For example, a small watershed with an area of 1 square kilometer has different active processes than the Mississippi River Basin.