Relationship between Turbid Water and Coral Damage Distribution Using ALOS AVNIR-2 Images and Diving Survey Data Immediately after the Heavy Rain Disaster of the Amami-Oshima Island, Japan

Yuji Sakuno,Katsuki Oki

doi:10.4236/ars.2015.41003

Abstract

To understand the relationship between turbid water and coral damage caused by the heavy rain disaster at the end of October 2010 in Amami-Oshima, Kagoshima Prefecture, Japan, turbid water and coral damage distribution monitoring was attempted using satellite imagery and a diving survey immediately after the disaster. ALOS AVNIR-2 images (spatial resolution: 10 m) on October 6 (before the disaster), October 24, October 30, and October 31 (after the disaster) were obtained as satellite data in 2010. The red-silt deposition index (RSI) map based on the method by Nadaoka and Tamura (1992) was also created. Moreover, a diving survey was conducted via the spot check method on December 18, 2010. As a result, comparison between the high turbidity (RSI) areas estimated using AVNIR-2 data and the coral damage areas judging from the field survey was considered relatively light. It is shown that satellite data such as AVNIR-2 can be a powerful tool to monitor damage distribution of coral reefs after heavy rain.

Highlights

Catastrophic natural disasters in recent years, such as the volcanic ash due to the explosion of Eyjafjallajökull, How to cite this paper: Sakuno, Y. and Oki, K. (2015) Relationship between Turbid Water and Coral Damage Distribution Using ALOS AVNIR-2 Images and Diving Survey Data Immediately after the Heavy Rain Disaster of the Amami-Oshima Island, Japan
The region of this study is the Amami-Oshima Island located in Kagoshima about 400 km southwest of Kagoshima City
The influence of the heavy rain disaster was not seen in Takahama-East (Stn. 1) or Takahama (Stn. 2), which accounts for more than 40% coverage of coral in the bay

Summary

Introduction

Catastrophic natural disasters in recent years, such as the volcanic ash due to the explosion of Eyjafjallajökull, How to cite this paper: Sakuno, Y. and Oki, K. (2015) Relationship between Turbid Water and Coral Damage Distribution Using ALOS AVNIR-2 Images and Diving Survey Data Immediately after the Heavy Rain Disaster of the Amami-Oshima Island, Japan. (2015) Relationship between Turbid Water and Coral Damage Distribution Using ALOS AVNIR-2 Images and Diving Survey Data Immediately after the Heavy Rain Disaster of the Amami-Oshima Island, Japan. Iceland in April 2010 [1] and the tsunami caused by the Great East Japan Earthquake disaster in the Japanese Tohoku district in March 2011 [2] have caused anxiety regarding their influence on aquatic animals and plants. A major problem is the sediment discharge that accompanies heavy rainfall and causes damage to corals in coral reef regions. The large-scale environmental evaluation of such coral reefs has often been performed using remote sensing techniques [3] [4]

Methods

Results

Conclusion