Site Analysis and Synthesis
This domain tests synthesis: turning inventory layers into constraints, opportunities, and a defensible site concept. Questions often ask you to read contours, infer drainage, or judge a proposed use against slope, sun, and wind.
Reading terrain
- Slope (%) = rise ÷ run × 100. A 1:12 ramp is 8.33%, not 12%.
- Water flows perpendicular to contours, from high to low. Contour V's point upstream (uphill).
- Closed contours with hachures indicate a depression; widely spaced contours indicate flat ground.
- Slope classes drive use: 0–5% is generally buildable and accessible; 5–10% needs grading; over 10–15% raises erosion, wall, and road concerns.
Sun, wind, views
- Aspect matters: south-facing slopes gain winter sun; north slopes stay shaded and wet.
- Shadow length depends on sun altitude; a low winter sun casts long shadows.
- Prevailing winter winds and summer breezes shape shelterbelts and building orientation.
- Viewshed analysis maps what can be seen from a point or corridor; a ridge or berm can block a view.
Worked example
A site has east–west contours (100, 102, 104) with a swale whose V points north. North is uphill, so water flows south. A proposed terrace on the south side would receive runoff from the slope above; place an intercepting swale uphill of the terrace and keep the building out of the swale centerline.
Traps
- Reading V's as pointing downstream.
- Treating inventory as analysis; analysis must state implications.
- Ignoring off-site views and noise sources.
- Assuming a south slope is always best without checking summer overheating or wind.