Neco 2025 Geography Question 49

Consider a triangular catch‑area defined by three points on a topographic map: A(0 km, 0 km) at 200 m elevation, B(4 km, 0 km) at 140 m elevation, C(0 km, 3 km) at 80 m elevation. The river leaves the catchment at point C, the lowest point.\n\n(a) Determine the average slope (in percent) of the catchment calculated from the highest point A to the lowest point C.\n(b) The runoff coefficient \(C_{r}\) for the catchment is given by \(C_{r} = 0.20 + 0.01S\), where \(S\) is the average slope in percent.\n(c) If the catchment receives a uniform rainfall of 120 mm during a storm, calculate the total runoff volume (in cubic metres) generated. Provide the runoff volume as an integer (rounded to the nearest cubic metre).