JP Gannon

Collegiate Assistant Professor
Forest Resources and Environmental Conservation
Virginia Tech

publications (google scholar)

An app for exploring discharge in a small mountain catchment

The Hubbard Brook Experimental Forest discharge app, hosted by CUAHSI, is a R shiny web application designed to allow students to explore the precipitation and discharge records of the 9 experimental watersheds at Hubbard Brook. It is similar in layout to the Gribble Gap Discharge app, but includes some added functionality.

The Gribble Gap Discharge app is a R shiny web application designed to give students a way to explore the discharge record of a headwater stream in a variety of ways.

Eventually this page will host some classroom activities, but for now, there is simply a list of topics that can be explored with the app.

Concepts to explore

Discharge variations over a water year

These are more apparent using the logged y axis

Storm dynamics

You can highlight days with certain precipitation amounts, so you can compare responses in different seasons and or wetness conditions. Use the “add horizontal line” to compare storm magnitudes easily.

Water balance concepts

Total discharge and precip in mm is included for the time period shown in the plots

Water temperature dynamics

Click the checkbox to add the water temperature record to the plots Water temperature data is only in the Gribble Gap app.

Baseflow dynamics

You can show baseflow, calculated using the EcoHydRology package in the plots. You can also change the filter parameter for the baseflow filter function.

Flow Duration/Non-exceedance curves

There is a probability of non-exceedance curve for the total flow and calculated baseflow. A second line appears if you zoom in to a specfic time-frame, which shows the curve for just that time frame. This can help illustrate what these curves show.


Plots can be copied via right click for pasting into documents.


If you use this app for a class or otherwise, I would greatly appreciate it if you let me know! Suggestions for features and/or information about bugs are also very welcome and encouraged.

You can contact me via direct message on twitter (@jp_gannon) or by email at jpgannon [at]


The data used in the app are hosted on CUAHSI Hydroshare and can be accessed here