In most design schools, Site Engineering is the most dreaded course in the landscape curriculum. It requires students to visualize three-dimensional landforms graphically and mathematically and to address multiple technical and environmental goals, all without sacrificing a larger sense of design. Even for the best-prepared students, it’s heavy lifting.
So a teacher is obliged to make the material accessible and meaningful. One way to do that, whenever possible, is to illustrate see each concept in three-dimensional “reality” before demonstrating how the related work is done on paper.
The standard text in the field, Strom and Nathan’s “Site Engineering for Landscape Architects” says:
A difficulty with understanding contours arises from the fact that they are imaginary and therefore cannot be easily visualized in the landscape.
Here are some ways that, during the first meeting of my class at the BAC’s Landscape Institute, I tried to help my students visualize what can’t be easily visualized:
1. Taking the advice of Civil Engineer and teacher extraordinaire Sandy Brock, I projected photos of landscapes onto a whiteboard and traced contours onto them in marker. I started with a photo of a rocky lakeshore in Central Park and asked the students to imagine the water rising, one foot at a time. With each foot’s rise, the lake had a new shoreline. A drawing showing all of those shorelines in plan would be a contour map. (This time I drew the contours; next time it’ll be the students doing the drawing.)
2. Next we went outdoors, to a nearby fringe of the Emerald Necklace. I divided the class into three groups and gave each group a line level, a line (string), some survey flags, and two dowels. I marked an “elevation zero” point with a survey flag and asked “group zero” to use the tools to trace a line across the landscape at that level, using more flags to pin down a line of survey tape as they went. The other groups, “plus two” and “minus two,” traced lines above and below the first one.
Within about fifteen minutes, we had drawn three contours on the land. Students were able to identify some surprises (“I didn’t expect so much change in elevation around the base of a tree;” “I didn’t expect the line to veer off to the side where the landscape flattens out”) and to interpolate the elevations where they happened to be standing. With luck, this will be good preparation when they’re asked to do the same kind of interpolation on paper.
3. Finally, I sent them home with an assignment: I asked each student to get ahold of an interestingly shaped vegetable (a squash or green pepper, for example), cut it in half, and draw a contour map of the “island” it formed when placed flat-side down. To draw the map, they will cut even horizontal slices of the vegetable and then trace the outline of each slice on paper, producing a contour drawing of the island. Then they will reverse the process, building a three-dimensional contour model of the vegetable by cutting corrugated cardboard to each contour and stacking the resulting pieces, carefully aligned and glued in place. Aside from the hands-on experience of literally “cutting” contours, I hope they will gain an understanding of the utility and the limits of the information that contours convey.
Results next week. It’s a strong group so my hopes are high.