Rain gauges are installed in order to measure rainfall totals and rainfall intensity. Rainfall intensity is a measure of the amount of rain over a specific period of time (e.g. centimeters/hour). It reflects the depth of water delivered to a point in the watershed per unit time. Intensity is important when comparing precipitation events with stream and groundwater response. We can address some of the following questions:
- During precipitation events, what flow paths does water take (e.g. Elsenbeer (2001) or Burt et al. (2011))?
- Is there a threshold relationship between rainfall intensity and response (i.e. Moody and others (2008))?
- What type of rainfall event(s) favor ground water recharge?
- How does rainfall differ between forested and cleared areas and does this effect stream response (Black, 1959)?
To measure the rainfall, a screened ring funnels water into a tipping mechanism that can hold 0.2 mm of rainfall. Once the bucket’s capacity is reached the mechanism tips, recording the date and time of each tip in the logger memory. Slope and fan sites were instrumented to determine the difference in rainfall intensity of canopied versus cleared areas. One is located at each Gribble Gap slope site (Wind and Glacier), and two others are located in the Gribble Gap Fan site. Aside from the tipping bucket gauges, we also have small plastic visual gauges that can be used to calibrate the tipping bucket data.
A detailed study that used these different gauge types and compared them is here.