Gradient CSEC Geography

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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 = Express gradient in the format VD:HD Vertical difference (in height) Horizontal distance (on the ground) 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 therefore the gradient VD:HD (60: 3000) is 1: 50 Vertical difference (in height) Horizontal distance (on the ground) 65 - 5 3000 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