Does anybody recognize our own Mt. Diablo in the image above? If you’re not familiar with topographic maps, you’re probably saying, “What?” Topography is the science of mapping land formations, and topographic maps like the one above allow their users to understand depth of valleys, steepness of hills, and where the flattest areas of ground lie. As Landscape Architects, the first step to any design is understanding the site, which includes the way the land is naturally shaped. Therefore, topography is invaluable to us for assessing and making decisions in our designed landscapes.
We hope we’re not causing anyone flashbacks to Architecture School! Cardboard contour models are a classic way to teach topography, because they ‘lift’ the squiggly lines of a flat topographic map up into 3D layers. If each cardboard edge corresponds with a contour line drawn on the map, you can see that each reconnecting line represents a ‘flat’ area which becomes steeper as more contour lines are ‘stacked’ inside of it. You can also see that when lines get closer together, the hill is steeper, and when they are farther apart there is shallower terrain. Just as the cardboard layers are all the exact same thickness, contour lines on a map are always the same height difference apart (6 inches, 1 foot, 10 feet, etc. depending on the map.)
If we could see contour lines in our everyday landscape, they would look something like this:
We wish we could see contours without the use of measuring equipment! But it can help to envision them roughly while walking on a site. If each of these white lines is 12 inches higher than the one before it, a 3-foot rise can be seen here from the base of the driveway to the top.
It’s necessary when designing a landscape to transform the land – to create flat areas for structures, a carved-out spot for a pool or trendy sunken living room, and raised berms for privacy. Cutting into slopes to remove soil and filling sunken areas for stability is needed even on a naturalistic site. However, while terrain changes must occur to accommodate landscape elements, there is something to be said for working with the existing landscape as much as possible. Often, this is just common sense. For example, it might be possible to build a structure on the naturally flattest area of the site, instead of going to great lengths to set it on a steep hill.
Understanding topography and hydrology (the way water moves over the land) can help us make design choices that minimize environmental impact and make construction so much easier. When grading is done without understanding of the natural landscape, problems can occur with runoff water and soil instability. Minimizing grading can cut down drastically on construction costs, and can also maintain the natural hydrologic cycles of a site and preserve soil health. Not to mention, sometimes the most interesting designs develop in response to land formations, such as this amphitheater-style slope shown above.
This J.Montgomery design shows contour lines in light grey. We made minimal changes to this existing landscape, adding only a low stone retaining wall, timber stairs down the slope and a vineyard. Minimal grading protects the watershed and the slope’s naturally rich topsoil, setting the vineyard up for success and providing a natural drainage solution.
While existing topography helps inform our choices in design, it doesn’t completely control our ability to change the landscape. When we do decide to make drastic changes to topography, we have to have a very good reason! This terraced landscape contrasts natural slopes with extreme terracing for a powerful impact. We cut into the hillside to create the perfect outdoor entertainment space, and employed geotechnical engineering (and a lot of serious equipment!) to create a terrace with an infinity-edge spa at the top. Complex systems relocate runoff water from hardscaped areas. The results are downright spectacular, making up for the steep design/construction budget with a steeper increase in property value. Worth it!