(一財)土木研究センターなぎさ総研からの刊行物のお知らせ

Dr. Takaaki Uda: Beaches in Okinawa and Recent Changes SECOND EDITION

Uda, T. 2021. Beaches in Okinawa and Recent Changes, Second Edition, Public Works Research Center, Tokyo, 455 pp.
定価 8,000円(税抜き)

 

本書、序文より

 

Preface

 

 The Okinawa archipelago, located in a subtropical area, has well-developed coral reefs along its coastline, and the excellent natural environment of the coasts had previously well maintained. This natural environment of the islands, however, is currently in a critical state because of the rapid development and the deterioration of natural coral reefs, particularly on the main island of Okinawa. Although there used to be many sandy beaches composed of coral sand, the number of such natural sandy beaches has been rapidly decreasing. The rise in the sea level due to global warming will also affect the stability of sandy beaches in Okinawa. To mitigate damage to the coasts and sandy beaches, it is necessary to determine present state of Okinawa’s coasts.
 For this purpose, the basic concepts on coastal engineering, by which anyone can understand the various phenomena on coasts, were first introduced in Chapter 1. Then, Okinawa’s coasts were geographically classified in Capter 2. Furthermore, in Chapters 3 and 4, the results of the field observations of the east and west coasts on Okinawa’s main island were summarized, respectively. Then, the present situation of the coasts on Miyako and Irabu Islands were summarized in Chapter 5. It is also important to understand the difference between the island’s coasts with coral reefs and the coasts located in Honshu, where large rivers flow into the ocean with abundant sediment discharge. In Chapter 6, therefore, the results of the field observation on the Abe River watershed and the field observation of the Chigasaki coast immediately after a large typhoon which hit this coast in 2019 and caused severe damage were described.

 

 

発  行:

一般財団法人 土木研究センター
 

著  者:

宇多 高明

 

発行年月:

令和3年7月

 

価  格:

8,000円(税別、送料別)


Contents

 
Preface
 

Chapter 1 Basic facts on coastal engineering

 

1.1

 

Definition of technical terms on beach topography

 

1.2

 

Shoreward sand transport on coral reef

 

1.3

 

Beach changes owing to construction of artificial structures

  1.4   Disappearance of buffer zone due to construction of protection facilities
  1.5   Prediction of beach changes using the BG model
  1.6   River mouth improvement and beach erosion on adjacent beaches
  1.7   Various measures
  1.8   Necessity of coastal zone management
 

Chapter 2 General characteristics of island coasts

 

2.1

 

Geographical classification of Okinawa’s coasts

 

2.2

 

Classification of Okinawa’s coasts by category

 

Chapter 3 Okinawa’s east coasts

 

3.1

 

Oku coast – Okinawa’s original natural coast

 

3.2

 

Higashi fishing port – Longshore sand movement on coral beaches

 

3.3

 

Fukuchi River mouth – Beach nourishment and river mouth closure

  3.4   Kayo coast – Damage by T1824 on September 29, 2018
  3.5   Kanna-Fukuji River – River mouth closure
  3.6   Tsuhako artificial beach – Windblown sand after beach nourishment
  3.7   Azama-sansan Beach – Windblown sand on artificial beach
  3.8   Azama-sansan Beach – Deposition of windblown sand by strong wind during T1824
  3.9   Argi Island – Construction of seawall at excessively seaward location
  3.10   Miibaru Beach – Appropriate location of landing pier for boats
  3.11   Oujima Island – Impact of seawall on sandy beach
  3.12   Oujima Island – Shoreward sand movement on coral reef
  3.13   Komesu Beach – Natural sandy beach
 

Chapter 4 Okinawa’s west coasts

 

4.1

 

Uga in Kunigami Village – Wave run-up

 

4.2

 

Tsuha Beach in Ogimi Village – Failure of seawall and river mouth closure

 

4.3

 

Yagaji coast on Yagaji Island – Beach changes trriggerd by construction of offshore fishing port

  4.4   Preservation of natural sandy beach on Kourijima Island
  4.5   Bise Village – Rows of Fukugi trees
  4.6   Minnajima Island – Beach changes triggered by artificial alteration
  4.7   Artificial beach in Nago City
  4.8   Agarie Beach in Nago City – Shoreline changes on artificial beach
  4.9   Agarie Beach in Nago City – Damage by T1824
  4.10   Sunset Beach – Notes in planning of a pocket beach
  4.11   Araha Beach in Chatan City – Formation of artificial beach and loss of sand
  4.12   Bibi Beach in Itoman City – Endless maintenance of artificial beach
 

Chapter 5 Coasts on Miyako and Irabu Islands

 

5.1

 

Higashi-hennazaki Point – Criff erosion and tsunami stones

 

5.2

 

Bora coast located on Higashi-hennazaki Point – Natural sandy beach

 

5.3

 

Separation of beach by seawall at Nagakita coast

  5.4   Conservation of natural coral beach and seawall construction at Manatsu Beach
  5.5   Sunayama Beach – Vegetation for blocking windblown sand
  5.6   Field observation of Yonaha – maebama Beach on Miyako Island
  5.7   Nagayama Beach – Restoration of beach
  5.8   Nagayama Beach – use of beach
  5.9   Toguchi-no-hama Beach – A natural beach
  5.10   Toguchi-no-hama Beach – the best natural beach
  5.11   Sawada-no-hama coral lagoon – Mangroves and tsunami stones
  5.12   Sawada Beach – Seawall and natural sandy beach
  5.13   Northwest end of Irabu Island – Separation by vertical seawall
 

Chapter 6

Field observation of Abe River watershed and Chigasaki coast in Kanagawa Prefecture
 

6.1

 

Abe River Watershed

 

6.2

 

Chigasaki coast – Damage due to storm waves associated with Typhoon No. 19 in 2019

 
Chapter 7 Conclusions
 


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