2. What are the factors that make the findings of the stream under study different from the characteristic feature of an ideal stream Discussion Topic:

3. Differences between stream under study and ideal stream (upper course)

4. Stream under studyIdeal stream 1.DischargeRelatively largerVery Small 2.WidthWider v-shaped river bed Sharp V-shaped river bed 3.DepthDeeper than middle course Shallow 4.Width- deep ratio Largersmaller Next

5. Differences between stream under study and ideal stream (upper course) Stream under studyIdeal stream 5.Pebble roundness Partly polished river load Angular river load 6.GradientGentleVery steep 7.VelocityRelatively higherLow Next

6. Differences between stream under study and ideal stream (upper course) Stream under studyIdeal stream 8.Water flow Less turbulentTurbulent with eddies 9.Special feature No pot hole is found.Uneven river bed, due to abrasion, and forms pot holes. Next

8. Sharp V-shape

10. Differences between stream under study and ideal stream (middle course)

11. Stream under studyIdeal stream 1.DischargeSmaller than upper course Medium 2.WidthRelatively wider than upper course Board V-shaped 3.DepthLess deep than upper course Medium deep Next

12. Differences between stream under study and ideal stream (middle course) Stream under studyIdeal stream 4.Pebble roundness Angular river load can be found Polished river load 5.GradientVery gentleGentle but steeper than lower course 6.VelocityLower than upper course Medium Next

13. Differences between stream under study and ideal stream (middle course) Stream under studyIdeal stream 7.Water flow More calmLess turbulent 8.Special feature Erosion and deposition take place Next

14. Erosion at outer bank Deposition at inner bank

17. Erosion at outer bank

18. Deposition at inner bank

19. Differences between stream under study and ideal stream (Lower course)

20. Stream under studyIdeal stream 1.DischargeSmaller than middle course (site 6) Large 2.WidthNarrower than site 5 Wide 3.DepthLess deep than middle course Deep 4.Width- deep ratio Site 6’s ratio is less than site 5’s. Next

21. Differences between stream under study and ideal stream (Lower course) Stream under studyIdeal stream 5.Pebble roundness River load deposited due to construction of dykes. Polished and round river load 6.Hydraulic radius Site 6’s radius is less than site 5’s. Lower the course, higher the radius is. 7.VelocityLower than upper course Medium Next

22. Differences between stream under study and ideal stream (Lower course) Stream under studyIdeal stream 8.Special feature Dykes are built. Next

23. Dykes narrowing the lower course.

25. Why the chosen stream is different from the ideal stream ?? Human Factor !!

27. Human Factor The chosen stream sections in Pak Tam Chung  modified by human -Bumping station -Construction work -Weit -Holiday Village -Catchwater

28. Human Factor DISCHARGE -Upper course smaller discharge  Catchwater( 引水道 ) built up, more discharge because of the water collection  Weir( 水堰 ) block the water flow, it smaller the discharge -Middle course greater discharge  The Holiday Village ‘s drainage system collect to the river, increase the discharge  Weir block the water flow, it smaller the discharge -Lower course discharge decrease  The bumping station bump the water away