Gradient CSEC Geography
- 1. GRADIENT How to calculate the gradient using a topological map RM ACCOUNTS ED ram@2011 reserved
- 2. Formula to be applied • Gradient is an expression of the change in elevation over the distance covered along the surface. • Gradient = Vertical difference (in height) Horizontal distance (on the ground) • Express gradient in the format VD:HD RM ACCOUNTS ED ram@2011 reserved
- 3. example Calculate the gradient of the road from the bridge at Cocoa Estate to the junction near the radio mast on the coast. (adapted from CSEC 2012 Geography CXC May/June – Qn 1(v)) RM ACCOUNTS ED ram@2011 reserved
- 4. Dominica (Lesser Antilles) Examine the contour lines that pass through each point for the heights; and use the scale to ascertain the distance RM ACCOUNTS ED ram@2011 reserved
- 5. Steps to take • Identify the heights of the two locations • Measure the distance in a straight line between the two points. • OR if specified, along the route identified (e.g the road, or river, etc) • Ensure that both the height and the distance have been expressed in the same units (i.e metres or feet) RM ACCOUNTS ED ram@2011 reserved
- 6. What do we now know? • The height of the bridge is 65 metres • The height of the junction is 5 metres • The measurement of the distance between the bridge and the junction is 3000 metres RM ACCOUNTS ED ram@2011 reserved
- 7. Applying the formula • Vertical difference (in height) Horizontal distance (on the ground) 65 - 5 3000 • therefore the gradient VD:HD (60: 3000) is 1: 50 RM ACCOUNTS ED ram@2011 reserved
- 8. sketched For every fifty metres (in distance) you advanced from the bridge towards the junction you would have descended one metre (in height) RM ACCOUNTS ED ram@2011 reserved