Proposal for the Investigation of Sandy Beach Erosion

1
Proposal for the Investigation of Sandy Beach
Erosion
A Case Study on Yilan, Taiwan

• by
• Department of Geography
• Associate Professor Hsueh-Mei Joyce Lin
• Research Assistant Ming-Jen Frank Chu

2
Outline

• Introduction
• Previous study
• Purpose
• Hypothesis
• Study Areas
• Data Manipulation
• Results
• Grid Analysis
• Final Products DEMs
• Conclusion

3
Introduction

• The sediment and gravels from Taiwans steep
  mountains and short rivers always provide a great
  source for supporting the islands sandy beach
  formation. In the past decades, several coastal
  development projects have been completed and have
  interrupted the balance of the transport. River
  improvement constructions also reduce the sand
  and gravels coming to the shore. These facts are
  causing Taiwans sandy beach erosion.
• Previous Study..

4
Previous Study

• You (1993) first claimed that several sections of
  Yilan shoreline have been retreating for 0.96
  meter annually from 1919 until 1987, and 7.9
  meters from 1979 until 1985.
• Report from First River Management Office (2002)
  pointed out that Yilans coast has eroded by
  tidal wave in the past decade.
• Chen et al. (2004) ran an analysis based on cross
  section histograms from FRMO, and discovered that
  majority of Yilans coast is eroding.
• Hsus (2005) study shows that the northern arc of
  Yilan coast is in its erosion process, especially
  in serious areas such as Dafu and Touchen.

5
Summary

• Long-term study You (1993) and Hsu (2005)s
  studies show that northern arc of Yilan coast is
  in erosion process however, southern arc is in
  deposition process.
• Short-term study Chen (2005) and First River
  Management Office (2005) discovered Yilan coast
  overall is in erosion process.

6
Purpose

• Previous related researches mostly focus on the
  adjustment of water line or area. Derive from the
  studies, this research will emphasize on the
  volume change throughout the short-term time
  range. Three beaches on Yilans coast have been
  selected, the GIS-based procedures will be
  integrated and to generate DTM for volume
  comparison and thus will support whether these
  areas are in its erosion or deposition process.

7
Hypothesis

• The formation of the sandy beach in Yilan
  requires both the sufficient sediment from
  Lanyang River and the energy of longshore
  current.
• The construction of river improvement,
  conservation of water and soil, sand/gravel
  mining reduce the volumes of sedimentation of
  Lanyang River.

8
Study Area

• Waiao Beach
• Dingliao Beach
• Wuweikung Beach

9
Data Manipulation

• Data Resource
• Select To select the most applicable data
  layer.
• Edit Topologically edit the attributes.
• Krige Interpolate the attributes into DTM.
• Clip Select the desired area for calculation.
• Conversion Convert the DTMs into TINs.

10
Resource

• F.R.M.O.
• 5 sub files
• Annotation
• Patch
• Polyline
• Polygon
• Point
• 69 layers
• Human structures
• Land Survey
• Landscape
• Nearly 50,000 records

11
Selecting

• Qualification
• Be able to show the location
• Must have elevation
• Have to be consistent

12
Editing Kriging

• Rules
• Can not overlap
• Can not be overlapped
• Kriging

13
Clipping
Cut the desired areafor conversion.
14
Converting
15
Results
The surface area is measured along the slope of
the surface it takes the variation in the height
of the surface into account. The volume is the
space between the surface and a reference plane
set at a particular height.
16
Grid Analysis

• Difference
• Before After

17
Difference between 2005 2006
18
(No Transcript)
19
Waiao Beach DEMs
20
Dingliao Beach DEMs
21
Wuweikung Beach DEMs
22
Next

• Q1 finished, before/after typhoon quarters, and
  Q4.
• To calculate waterline area change rates.
• To set up Beach degradation indicators.
• To gather and introduce tides, waves data.

23
Conclusion

• This presentation demonstrates a method to detect
  onshore adjustment, and the volume change numbers
  are based on the best available data at the time
  of preparation. Updates to the DTM will be
  performed as new data becomes available.

24
Thank you foryour participation.
Ming-Jen Frank Chu fc713_at_hotmail.com