Geography Field Trip Report

1
GeographyField Trip Report

• Group member
• Poon Yau Nga Zeeta
• Ma Sin Fong
• Lee Yuk Ka
• Lee Hoi Ping

2
Introduction

• The location of the field trip is at Mui Wo on
  the Lantau Island and Cheung Chau
• We went for this site and did this project
  because we-study river morphology through the
  trip-study the processes of river transportation
  -learn more about the characteristics of river
  deposition-identify the features of different
  river courses
• Our project will mainly focus on Point A of this
  field trip

3
Types of river erosion at Point A

• Site A is the upper course of stream, erosion
  is the main work, there are two main erosion
• Headward erosion
• -It occurred when water starts to flow to
  the lower course
• Vertical erosion
• -It becomes dominant when water
  concentrates on the shortest path as it runs down
  the steep slope. Waterfall is also formed.

4
Direction of river erosion

• At site A of the upper course, the directions
  of the erosion are
• Vertical erosion/downcutting
• A river removes rocks from its bed
• The valley is deepened
• Headward erosion
• Loose rock debris is brought down by the overland
  flow running down the slope behind the river
  source
• The river source extends backwards
• The valley is increased in length

5
Feature at Point A

• At point A, there are many features below
• Waterfall

6
Formation of waterfall

• It forms when the river water is unable to remove
  
• the resistance rock layer but is enough to erode
• the less resistance rock downstream
• the river falls vertically down
• Waterfall is formed

7

• Formation of waterfall of step 1
• The river water is unable to remove

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Step 2

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Step 3 4

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Plunge pool
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Formation of Plunge pool

• When the falling water at the waterfall produces
  strong hydraulic action
• It has a circular hollow filled with water
• Plunge pool is formed

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Formation of the plunge pool of step 1

• The falling water at the waterfall produces
  strong hydraulic action

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Step 2

• It has a circular hollow filled with water

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Potholes
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Formation of potholes

• When a river flows over an uneven and rough
  surface
• It causes turbulence in the water
• The water drills hollows with the load it carries
  
• Hollows are called potholes

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What are the types of river transportation?

• Solution
• Suspension

How do you know they are taking place in your
site?

• Not obvious
• Little energy in upper course
• There are some big rocks

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What are the characteristics of lower course?

• Compare with upper and middle course
• Wider
• Deeper
• More energy
• Size of bed load is smaller
• More winding
• Flatter
• Presence of farmland
• Presence of woodland

18
What is the height difference among Point A, C
and E?

• The height of different points
• Point A 40m
• Point C and E 0m

19
Which points will suffer from flooding?

• Point C and E

Why?

• They both belong to lower course
• Larger discharge
• Channel bed is covered by sediment
• -Little friction and smooth
• -has the largest energy
• As a result
• Load in the river is carried to valley floor
  and causes flooding

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How to prevent flooding?

• The sustainable measures
• Reduce the peak discharge
• increase the storage capacity of river
• building spillways
• Increase the bankfull discharge
• preventing silting
• soil conservation

21
References

• http//www.school-portal.co.uk/GroupDownloadFile.a
  sp?file21604
• http//ihouse.hkedcity.net/hm1203/hydrosphere/riv
  er-pothole.htm

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• End of the field trip project