Wes Marshall, P.E. University of ConnecticutJanuary 2007

CE 276Site Design

Introduction to Site DesignChapter 1 – Contours & Land Form

Chapter 1Contours & Form

Contours

The ability to visualize, analyze,

and interpret landforms from

contour maps is an essential skill

(http://www.nelsap.org/ct/uconntopo.jpg)

Contours

What is a contour? An imaginary line connecting points of equal

elevation

Contours on a topographic map is the most common & convenient way of representing land form Other methods:

Physical models Computer models (Digital Terrain Models… DTM)

Visualizing Contours

(Booth, Basic Elements of Landscape Architecture)

Visualizing Contours

(http://www.rbgilbert.com/images/harvardstadium10.jpg)

Visualizing Contours

(http://www.uconnhuskies.com/AllStories/MFootball/2003/04/17/20030417a.html)

(http://nels.uconn.edu/images/Mirror/page_01.htm)

Contour Characteristics

Contours are continuous lines creating closed figures Closure may not be shown within the map limits

Contour Characteristics

2 or more contour lines are required to indicate: 3-D forms Direction of Slope

Contour lines never cross except in rare circumstances (i.e. overhanging cliff)

Contour Characteristics

The steepest slope is perpendicular to the contour line This is because it has the greatest

vertical change in the shortest horizontal distance

Thus, water flows perpendicular to contour lines

Contour Characteristics

Equally spaced contour lines indicate a constant, or uniform, slope As contour lines get

closer together, the slope is getting steeper

Contour Characteristics

Contour lines never divide or split in the natural landscape However, at buildings or other structures,

contour lines can give the appearance of splitting

Landforms

Various types of landforms Ridge Valley Summit Depression Uniform Slope Convex and Concave slopes Gap Saddle

Ridge & Valley

Ridge Raised elongated

landform typically with a highpoint

Valley Elongated depression

forming between the space of two ridges

The two are interconnected because the ridge side slopes create the valley walls

Summit & Saddle

Summit Hill or mountain containing the

highest point elevation Represented by a set of

concentric contours with the highest contour at the center

Saddle Dividing point between two

valleys (or swales) The high point between the two

valleys and a low point between the ridges creating the valleys

Saddle, Summit, & Valley

Depression

Depression Contains the lowest

point elevation Represented by a set

of concentric contours with the lowest contour at the center

In order to distinguish from summits, you need to know the directions of the slopes

Uniform Slope

Uniform Slope Constant slope Contour lines

spaced at equal distances

More typical in constructed landscapes than in the natural environment

Convex Slope

Convex Slope Contour lines are

spaced at decreasing distances in the downhill direction

Slope is flatter at higher elevations and progressively steeper at the lower elevations

Concave Slope

Concave Slope Contour lines a re

spaced at increasing distances in the downhill direction

Slope is steeper at higher elevations and progressively flatter at the lower elevations

Convex & Concave Slopes

Concave Slope & Summit

Convex Slope & Valley

Gap

Gap Distinct break in

ridgeline

Water Gap

How to Draw a Section

a) Indicate section plane

b) Draw lines parallel to cutting plane to represent vertical scale

c) Project plan view contour elevations onto section view

d) Connect the dots

plan view

section view

Questions

True or False? All contours eventually close on themselves.

A _________ slope is said to occur when contour lines are spaced at increasing distances in the downhill direction.

True or False? Water flows parallel to contour lines.

True or False? For the same scale and contour interval, the steepness of slope increases as the map distance between contours increases.