We use a number of Onset rain gauges in Grand Canyon National Park. We’re investigating the rates and timing of precipitation which recharge the aquifer systems below the canyon rim. We’ve set up a network of rain gauges on the rim as well as at different elevations that correlate with changes in vegetation type below the rim. This allows us to look at how precipitation rates vary along the rim and all the way down to the Colorado River.

We also have rain gauges at three springflow gauge sites to see how much rain is falling at those locations and look at the intensity and timing of storms and the relation to spring discharge and flash floods.

Some of the rain gauges are in very remote and harsh locations, and it can take a full day just to get to them. Some of them have been working reliably since 2001.

We offload the data four or five times a year using a data shuttle. We then use HOBOware to take the data in and export into Excel. Then I plot it up and compare the data to other information like spring discharge and temperature.

We’ve run trend analyses on the discharge at the three springflow gauges because the area has been in drought and have seen decreases in spring discharge at some of these sites. We’re using the collected data to help understand if this is a result of groundwater pumping that is occurring just outside the Park boundary, the drought conditions, or a combination of the two.

Because the equipment is deployed in the National Park, we want to keep it out of the way and inconspicuous. At a few locations, we surround the rain gauge with rocks so it remains open to the sky but is not visible. There are also some attached to existing structures in the Park so they’re out of the way. We plan to expand the rain gauge network in 2009.