FC: THE 'HOW TO' OF GRADIENTS IN TOPOGRAPHIC MAPS | By: SarahMcFadyen
1: By the end of this lesson you should be able to do the following: - define gradient - Work out the gradient of the slope and its formula - Understand why it is important
2: DEFENITION OF GRADIENT | > The gradient of a slope is simply a measure of its steepness. > Gradient signs can often be seen on mountain roads and are generally expressed 'gradient 1:10' (which means 1 vertical drop for every 10 horizontal units). > Gradient can also be used interchangeably with slope, grade, incline and pitch when using topographic maps.
3: DEFENITION OF GRADIENT | > It uses the same concept of 'rise over run' as we do in maths. The Gradient is used when we, as geographers need to know the angle of the slope > It is typically expressed as a percentage, angle or ratio. i.e. Vertical distance (rise) ------------------------------ Horizontal distance (run)
4: NOW ITS YOUR TURN!! | For example; a) say the rise is 20m and the run 5m what is the gradient of this slope?
5: 20/5 = 4 km so, gradient is 4
6: ITS IMPORTANCE | > Important as by calculating the gradient geographers are able to assess the relative decline or incline of the slope. > The type of slope is EXTREMELY IMPORTANT when navigating. By identifying the type of slope we can then determine whether to travel up or around it
7: THE TYPES OF SLOPES | > The three types of slopes are: 1) Concave slopes 2) Convex slopes 3) Uniform slopes
8: CONCAVE SLOPES | > The majority or concave slopes can be found on steep hills which ease out into a flat plain. > The closer the contour lines are the steeper the hill > Concave slopes contour lines will be closely spaced at the top of the terrain feature and widely spaced at the bottom
10: CONVEX SlOPES | > The hill will start off with a gentle slope and may suddenly become very steep. The wider spaced contours are located at the top while the closer contours are found at the bottom of a convex slope
12: UNIFORM SLOPES | > A uniform slope is a slope with evenly spaced contours, it can be hills of any gradient, but the contours must be evenly spaced > A steep hill and a hill with a gentle slope can be both classified as a gentle slope. If all the contours are evenly spaced apart no matter how close or far apart they are, it is a uniform shape
14: IN SUMMARY..... | > Gradient is the unit of measurement used in calculating the steepness of the slope > To work out the gradient the formula of rise over run id used > There are three types of gradients: concave, convex and uniform slopes