A river descends from an elevation of 800 m at its source to 200 m at its mouth over a straight‑line distance of 120 km. The river is divided into three consecutive sections: upper (first 40 km), middle (next 50 km) and lower (last 30 km). The gradient of the upper section is 5 m km⁻¹ and that of the lower section is 1 m km⁻¹.

(a) Determine the gradient of the middle section.
(b) Classify each section as "steep", "moderate" or "gentle" using the criteria: steep  4 m km⁻¹, moderate 2-4 m km⁻¹, gentle 

Question

A river descends from an elevation of 800 m at its source to 200 m at its mouth over a straight‑line distance of 120 km. The river is divided into three consecutive sections: upper (first 40 km), middle (next 50 km) and lower (last 30 km). The gradient of the upper section is 5 m km⁻¹ and that of the lower section is 1 m km⁻¹.

(a) Determine the gradient of the middle section.
(b) Classify each section as "steep", "moderate" or "gentle" using the criteria: steep > 4 m km⁻¹, moderate 2-4 m km⁻¹, gentle

Accepted Answer

Middle gradient = 7.4 m km⁻¹; Upper - steep (V‑shaped valley); Middle - steep (V‑shaped valley/gorge); Lower - gentle (floodplain or meander plain).

Neco Model Questions Vol1 2019 Geography Question 5

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