Observation of Ozegahara mire and estimation of environmental changes using satellite radar
| Autor: | Hisada, Yasuhiro, Ogawa, Yoshiko, Demura, Hirohide |
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| Jazyk: | japonština |
| Rok vydání: | 2022 |
| Předmět: | |
| Zdroj: | 低温科学. 80:123-134 |
| ISSN: | 1880-7593 |
| Popis: | 尾瀬ヶ原は本州最大の湿原であり，東西6キロ，南北2キロにわたる広大な地域で，かつ環境保護のため木道以外の立ち入りが厳しく制限されている．そのため，立ち入ることのできない領域の動植物相，水文・水質などを把握することが困難である．本稿では，人工衛星に搭載された合成開口レーダー（SAR: Synthetic Aperture Radar）による観測に基づいて，木道付近に制限されることがない湿原の環境について推定する．尾瀬ヶ原全域に対する夏季，冬季のSAR画像から，湿原域・非湿原域の推測が可能だった．また，背中アブリ田代と泉水田代のSAR画像とドローンによる空撮画像との詳細な比較から．湿原域の識別を追認し，ドローン画像では識別が困難な土砂堆積領域を識別できた．また，植生に対応した調査地点の3衛星に亘る後方散乱係数の時系列変化から，各衛星レーダーのセンサー感度が異なっている可能性が高く，全期間にわたって比較することは困難であった．しかしながら，後方散乱係数の取る値は植生によって異なり，ミズゴケクラス＜ヌマガヤオーダー＜拠水林という関係になっている．いくつかの調査地点において後方散乱係数の上昇傾向が認められたが，その要因の一つとして考えられる降水量との関係性は明らかにできなかった． Ozegahara mire is the largest wetland in Honshu, Japan, covering a vast area of 6 km from east to west and 2 km from north to south, and access to this area is strictly restricted except by wooden roads for environmental protection. Therefore, it is difficult to grasp the flora, fauna, hydrology, and water quality in the inaccessible areas. In this paper, we estimate the environment of the wetland based on observations using Synthetic Aperture Radar(SAR) onboard the satellite. From the SAR images of the entire Ozegahara area in summer and winter, it was possible to discriminate between mire and non-mire areas. By comparing the SAR images of Senaka-aburi tashiro and Sensui tashiro with the aerial images taken by a drone, we were able to reconfirm the identification of mire areas and to identify the area where sediment was deposited, which was difficult to identify in the drone images. Based on the results of the time series of backscatter coefficients across the three satellites (JERS-1, ALOS-1, 2), it was difficult to direct compare the results over the entire period because the sensor sensitivity of each satellite radar was likely to be different. However, it was shown that the value range of the backscatter coefficient varied depending on the vegetation. Although there was an upward trend in the backscatter coefficient at some of the investigation sites, the relationship with precipitation, which could be one of the factors, could not be clarified. |
| Databáze: | OpenAIRE |
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