1 / 18

River features – Upstream portion

River features – Upstream portion. River Channel: small, narrow, rough and usually shallow. When rivers have to flow round obstacles of hard rocks in its path (spurs), it develops a winding course. River features – Upstream portion. River features – Upstream portion.

jessicawatkins
Download Presentation

River features – Upstream portion

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. River features – Upstream portion River Channel: small, narrow, rough and usually shallow. When rivers have to flow round obstacles of hard rocks in its path (spurs), it develops a winding course.

  2. River features – Upstream portion

  3. River features – Upstream portion • Rapids: a series of short and fast-flowing turbulent falls of water along a part of the river. • Water is relatively shallow.

  4. River features – Upstream portion

  5. River features – Upstream portion • Formation of rapids: • River flows over an area of alternating bands of gently inclined resistant and less resistant rocks. • Less resistant rocks are eroded faster. • river flows swiftly when it flows over outcrops of resistant rocks.

  6. River features – Upstream portion 2) Waterfalls Sudden fall of water along a course of a river. Water plunges down almost vertically and rapidly into a deep valley

  7. River features – Upstream portion • Formation of waterfall: • forms when a river flows from a band of resistant rock to less resistant rock. • band of resistant rock can lie horizontally, vertically or dip upstream • less resistant rock that lies downstream will be eroded faster than the resistant one

  8. River features – Upstream portion • Formation of waterfall: • differential erosion causes a change in gradient of river. • over time, the river bed will be steepened. • water plunges down almost vertically and rapidly as a waterfall.

  9. River features – Upstream portion

  10. River features – Upstream portion • Formation of waterfall (cont’d) • when faulting causes land to be displaced, waterfalls can also form. • One block of land will be uplifted relative to the adjacent block. • This displacement causes a difference in height. • Water cascades down the fault scarp.

  11. River features – Upstream portion

  12. River features – Upstream portion 3) Plunge Pools A depression at the foot of a waterfall. This depression is excavated, enlarged and deepened by hydraulic action of the plunging water. Rock debris erodes the depression by abrasion to furthur enlarge and deepen it.

  13. River features – Upstream portion 4) Gorges Deep narrow valleys with almost vertical sides.

  14. River features – Upstream portion

  15. River features – Upstream portion

  16. River features – Upstream portion 5) Potholes Depressions of different sizes in the river bed. Formed by river abrasion. Abrasive action especially effective in flood conditions

  17. River features – Upstream portion

  18. River features – Upstream portion http://library.thinkquest.org/28022/

More Related