Water balance lab preparation
Associated lecture materials
To prepare for lab activities, first be sure you have reviewed the associated materials from lectures on watershed delineation and water budgets.
Contents of this module
Topographic watershed delineation
The first lab exercise is to get some practice visualizing flow nets based on surface topography and delineating watersheds using topographic maps. To be prepared, you might want to review the following video from lecture that provides a detailed example of topographic watershed delineation (13:09 min).
You will be asked to delineate a watershed using the drawing tools in Microsoft PowerPoint. Understanding how to control curved lines in PowerPoint to the degree necessary to represent watershed boundaries is a useful skill for any drawings made for presentations or other PowerPoint applications. You will want to download the following PowerPoint file if you wish to follow along with the video.
Let's review drawing watershed boundaries by taking full control of lines in PowerPoint (15:24 min).
Water budget comparisons during the Hubbard Brook experiment
Evapotranspiration is a difficult variable to measure directly at watershed scales. In the 1960s, a famous experiment at the Hubbard Brook Experimental Forest was conducted in an attempt to directly observe the role of transpiration in watershed water budgets. The approach was to remove and suppress vegetation growth for three years while monitoring runoff from the catchment continuously before, during, and after the treatment. Another exercise in this laboratory is to use long-term annual precipitation and hydrograph data from Hubbard Brook to rigorously explore the effect of the vegetation removal experiment on water budgets and watershed partitioning (13:53 min).
The following document provides some more useful hints for the completion of laboratory activities.
Powerpoint and Excel drawing tips.pdf