The Wutach flows through a narrow, wooded gorge below exposed rock walls in the Black Forest.

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Preparing the 3D view

Preparing lighting and the first complete frame…

Model scale

Invented 6 × 4 km catchments. relief ×2. three selected stages.

Before capture: two separate drainage routes.

How to read these results

The gold arrow shows headward extension, opposite the captor’s downstream flow. Stages are selected geometry, not a dated erosion simulation. Play follows the current water route.

River capture

Explain how headward erosion can divert a river’s headwaters and identify evidence left in the old channel.

Drag to rotate. Hold Ctrl and scroll to zoom, or pinch on a touch screen.

Why it happens

Headward erosion can extend one river into a neighbouring basin and divert its headwaters. The new route may leave an elbow of capture and a former valley carrying a much smaller stream.

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Wutach Gorge, Germany. Capture diverted drainage from the Danube system towards the Rhine; subsequent incision cut this gorge.

Try a comparison

Step towards the divide and then After capture; play the changed water route.

Reading the result

The chosen stages show one capture mechanism; their spacing does not represent an erosion rate or dated sequence.

A common misunderstanding

A drainage divide is permanent, so one river cannot gain another river’s headwaters.

Erosion, tectonic change or other landscape adjustment can shift a divide and divert flow into a neighbouring basin. The capturing river gains drainage area while the former channel may carry a smaller stream. Landforms such as wind gaps can help reconstruct the change.

Cases

Exam language

Elbow of capture

A sharp bend marking where one drainage system has diverted water from another. It can help reconstruct river capture when combined with a wind gap or underfit valley. A sharp bend alone is not enough to prove capture.

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Wutach Gorge, Germany. Capture diverted drainage from the Danube system towards the Rhine; subsequent incision cut this gorge.

Beheaded stream

A stream whose former headwaters have been diverted into another drainage system by river capture.

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The Aitrach valley preserves the former route of the Feldberg Danube. Capture by the Wutach diverted its large upstream flow towards the Rhine, leaving the small Aitrach in an oversized valley. The channel itself is difficult to distinguish in this landscape view.

Pirate stream

The stream that gains water by capturing the headwaters of another drainage system. It may extend its valley by headward erosion. The term describes a changed drainage connection, not a different type of flowing water.

Wind gap

A valley crossing a drainage divide that no longer contains the stream that cut it. It can be evidence of river capture or another drainage change. Compare its shape with neighbouring valleys and the present stream network.

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Bald Eagle Mountain, Pennsylvania. The wind gap crossed by Route 15 is left of centre; Hagermans Run occupies a separate water gap to the right. A wind gap lacks the through-flowing river found in a water gap.

Headward erosion

The extension of a valley or channel back towards its source by erosion. Over time it can shift a drainage divide and help one river capture another’s headwaters. It describes growth upstream, not water flowing uphill.

Watershed

In UK geography, the drainage divide separating basins. In US usage, watershed commonly means the entire drainage basin; check the context.

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ASTER, 24 September 2005: tributaries dissect sandstone in Canyonlands, Utah. A drainage network collects flow towards a main river.

Misfit stream

A stream smaller than the valley it occupies, sometimes following river capture or the loss of former glacial meltwater discharge.

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A photographed misfit stream. Its present flow is small relative to its valley; former glacial meltwater or a change in drainage may explain the mismatch.

Process0.40Formation stage