This difference is called relief. The difference is computed by finding the highest elevation and the lowest elevation in the area of interest and subtracting the two numbers. Gradient Gradients can also be calculated from topographic maps which show contour lines. Gradients are quite useful from a variety of perspectives including determination of the slope of a river and the determination of the slope of a hill. Steep slopes are often dangerous and difficult to drive or float.
Gentle slopes are often more stable and easier to negotiate if one is paddling a canoe up stream.
Gradient is calculated by measuring the map distance between two contour lines and dividing the difference in elevation indicated by the difference between contour elevations by the distance. Please go to the Menan Butte Map Reading Exercise.