Drainage divide stability at Wulashan, northern margin of the Ordos block, China: Evidence from the analysis of χ value

Abstract

The stability of drainage divides carries important tectonic and climatic information. However, there is still no consensus on the criterion for measuring the stability of drainage divides, which may lead to different conclusions. There are two different views on the stability of the divide at the Wulashan horst, northern margin of the Ordos block: The drainage divide is moving northward, according to the comparison of drainage-basin morphology (such as elbows of capture, knick points); The drainage divide remains stable, according to the comparison of Gilbert metrics. In this study, we used the χ-plot method to check both the stability of the Wulashan drainage divide and the reliability of the above methods. The analysis shows that the χ value at the top of the northern side is higher than that at the same elevation of the southern side if a lower baseline was set (1300 m a.s.l.); If a higher baseline (~1800 m a.s.l.) is set, the χ values on both sides of the divide are the same at the same elevation. Because the tilting has relatively less influence, the χ-plot with a higher baseline is more representative of the drainage divide stability. In summary, the result supports the view that the drainage divide at the Wulashan horst is at a steady state. Moreover, we discussed the limitations of the methods in measuring the stability of drainage divides.

Keywords

• drainage divide
• wulashan horst
• χ value
• tilting