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| River Thaw | |
|---|---|
 The River Thaw south of Cowbridge | |
 | |
| Native name | Afon Ddawan (Welsh) |
| Location | |
| Country | United Kingdom, Wales |
| Region | South Wales |
| County | Vale of Glamorgan |
| Cities | Cowbridge, Llanblethian, Aberthaw |
| Physical characteristics | |
| Source | |
| • location | Southwest of Llanharry, Vale of Glamorgan, Vale of Glamorgan, Wales |
| • coordinates | 51°30′30″N 3°27′03″W / 51.5082°N 3.4509°W |
| Mouth | |
• location | Bristol Channel |
• coordinates | 51°22′58″N 3°23′46″W / 51.3828°N 3.3961°W |
| Length | 20.0 km (12.4 mi) |
| Discharge | |
| • location | Breaksea Point, Vale of Glamorgan |
| Basin features | |
| Tributaries | |
| • left | Kenson River, Nant Tre-gof, Nant Aberthin |
| • right | Nant y Stepsau, Factory Brook |
The River Thaw (Welsh: Afon Ddawan) (also Ddaw) is a river in the Vale of Glamorgan, south Wales. At 20 kilometres/12.4 miles, it is the longest river entirely in the Vale of Glamorgan.[1]