GIS Applications in Hydrologic Processes

John Van Hoesen,


Students compare traditional paper-based techniques associated with estimating areal precipitation, watershed delineation, and modeling evapotranspiration. This assignment challenges students to consider the various assumptions involved with both analog and digital analyses and highlights the strengths and weaknesses of both approaches.


Type and level of course
This assignment is used in an undergraduate hydrogeology course, which is offered as an upper-division elective.

Geoscience background assumed in this assignment
I assume students have taken Intro to Geology and Geomorphology prior to entering this course. Students should have a strong understanding of basic geologic concepts and a good understanding of processes influencing surfical materials and surface waters. Many of these concepts are being covered for a second or third time, but this assignment forces them to think more about the assumptions rather than the processes.

GIS/remote sensing skills/background assumed in this assignment
I assume that most students have had some exposure to GIS-based assignments but not an entire course covering GIS. They should be familiar with the basic tools of ArcGIS and have a familiarity with spatial data formats.

Software required for this assignment/activity:
ArcView 9.2 or higher, Spatial Analyst, Excel

Time required for students to complete the assignment:
Two hours in class and depending on the student, another two to four outside of class.


GIS/remote sensing techniques students learn in this assignment
Students learn how to: (1) manipulate raster and vector data formats, (2) interpolate Thiessen polygons, (3) convert between raster and vector formats, (3) utilize ArcToolbox hydrology and solar radiation functions, (4) utilize the Raster Calculator, and (5) create and edit vector layers.

Other content/concepts goals for this activity
Students learn how to: (1) estimate areal precipitation, (2) delineate and characterize watersheds, and (3) estimate evapotranspiration.

Higher order thinking skills goals for this activity
Students are asked to: (1) evaluate assumptions and limitations of simple GIS-based models, (2) evaluate the results of these modeling efforts, and (3) compare and contrast analog and digital techniques.

Description of the activity/assignment

Prior to working on this assignment, students complete exercises that require them to use traditional techniques to estimate areal precipitation, watershed boundaries and evapotranspiration (e.g. - topographic maps, tracing paper, graph paper, planimeters, and calculators). This assignment asks them to evaluate the strengths and weaknesses of using a GIS to perform similar analyses. Because there is repetition in the location and types of analyses, the exercise allows students to spend more time evaluating assumptions and limitations instead of learning new concepts.

Determining whether students have met the goals

I collect the entire GIS directory of each student and explore their workflow to evaluate their organization, analyses, and final models. They area also asked to write a final report summarizing their findings and interpretations of the assignment.
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