How can stream flow direction be determined on a contour map?

How can stream flow direction be determined on a contour map?

• A. By contour turnbacks and elevation differences
• B. By color shading
• C. By map scale
• D. By contour density

Answer: (A)

Contours encode how the land slopes, and streams always move downhill along that slope. When a stream crosses a contour line, the line forms a V shape with the point of the V pointing uphill toward higher ground. The water in the stream flows in the opposite direction of that V point, downstream toward lower elevations. The sequence of contour values confirms this: as you move downstream, elevations get lower. The spacing of contours also matters—tight spacing means a steep slope, which the stream follows as it descends. Color shading, map scale, or how dense the contours appear don’t reliably indicate flow direction by themselves, so they don’t provide the same directional cue.

Contours encode how the land slopes, and streams always move downhill along that slope. When a stream crosses a contour line, the line forms a V shape with the point of the V pointing uphill toward higher ground. The water in the stream flows in the opposite direction of that V point, downstream toward lower elevations. The sequence of contour values confirms this: as you move downstream, elevations get lower. The spacing of contours also matters—tight spacing means a steep slope, which the stream follows as it descends. Color shading, map scale, or how dense the contours appear don’t reliably indicate flow direction by themselves, so they don’t provide the same directional cue.