scholarly journals Synergic use of Sentinel-1 and Sentinel-2 data for automatic detection of earthquake-triggered landscape changes: A case study of the 2016 Kaikoura earthquake (Mw 7.8), New Zealand

2021 ◽  
Vol 265 ◽  
pp. 112634
Author(s):  
Jan Jelének ◽  
Veronika Kopačková-Strnadová
2020 ◽  
Vol 65 (2) ◽  
pp. 89-91
Author(s):  
Bin Shan ◽  
Yashan Feng ◽  
Chengli Liu ◽  
Zujun Xie ◽  
Xiong Xiong

2020 ◽  
Author(s):  
Lorena Abad ◽  
Daniel Hölbling ◽  
Raphael Spiekermann ◽  
Zahra Dabiri ◽  
Günther Prasicek ◽  
...  

<p>On November 14, 2016, a 7.8 magnitude earthquake struck the Kaikōura region on the South Island of New Zealand. The event triggered numerous landslides, which dammed rivers in the area and led to the formation of hundreds of dammed lakes. Landslide-dammed lakes constitute a natural risk, given their propensity to breach, which can lead to flooding of downstream settlements and infrastructure. Hence, detecting and monitoring dammed lakes is a key step for risk management strategies. Aerial photographs and helicopter reconnaissance are frequently used for damage assessments following natural hazard events. However, repeated acquisitions of aerial photographs and on-site examinations are time-consuming and expensive. Moreover, such assessments commonly only take place immediately after an event, and long-term monitoring is rarely performed at larger scales.</p><p>Satellite imagery can support mapping and monitoring tasks by providing an overview of the affected area in multiple time steps following the main triggering event without deploying major resources. In this study, we present an automated approach to detect landslide-dammed lakes using Sentinel-2 optical data through the Google Earth Engine (GEE). Our approach consists of a water detection algorithm adapted from Donchyts et al., 2016 [1], where a dynamic threshold is applied to the Normalized Difference Water Index (NDWI). The water bodies are detected on pre- and post-event monthly mosaics, where the cloud coverage of the composed images is below 30 %, resulting in one pre-event (December 2015) and 14 post-event monthly mosaics. Subsequently, a differencing change detection method is performed between pre- and post-event mosaics. This allows for continuous monitoring of the lake status, and for the detection of new lakes forming in the area at different points in time.</p><p>A random sample of lakes delineated from Google Earth high-resolution imagery, acquired right after the Kaikōura earthquake, was used for validation. The pixels categorized as ‘dammed lakes’ were intersected with the validation data set, resulting in a detection rate of 70 % of the delineated lakes. Ten key dams, identified by local authorities as a potential hazard, were further examined and monitored to identify lake area changes in multiple time steps, from December 2016 to March 2019. Taking advantage of the GEE cloud computing capabilities, the proposed automated approach allows fast time series analysis of large areas. It can be applied to other regions where landslide-dammed lakes need to be monitored over long time scales (months – years). Furthermore, the approach could be combined with outburst flood modeling and simulation to support initial rapid risk assessment.</p><p> [1]   Donchyts, G., Schellekens, J., Winsemius, H., Eisemann, E., & van de Giesen, N. (2016). A 30 m resolution surface water mask including estimation of positional and thematic differences using Landsat 8, SRTM and OpenStreetMap: A case study in the Murray-Darling basin, Australia. Remote Sensing, 8(5).</p><div> <div> </div> </div>


2018 ◽  
Vol 45 (2) ◽  
pp. 292-308 ◽  
Author(s):  
Rosi Crane ◽  
B. J. GILL

William Smyth, unable to get work in a New Zealand museum, ran a commercial taxidermy business at Caversham, Dunedin, from about 1873 to 1911 or 1912. His two decades of correspondence with Thomas Frederic Cheeseman at the Auckland Museum provide a case study of Smyth's professional interaction with one of New Zealand's main museums. We have used this and other sources to paint a picture of Smyth's activities and achievements during a time when there was great interest in New Zealand birds but few local taxidermists to preserve their bodies. Besides the Auckland Museum, Smyth supplied specimens to various people with museum connections, including Georg Thilenius (Germany) and Walter Lawry Buller (New Zealand). Smyth was probably self-taught, and his standards of preparation and labelling were variable, but he left a legacy for the historical documentation of New Zealand ornithology by the large number of his bird specimens that now reside in public museum collections in New Zealand and elsewhere.


2021 ◽  
Vol 182 ◽  
pp. 105962
Author(s):  
Hongyan Zhang ◽  
Hongyu Du ◽  
Chengkang Zhang ◽  
Liangpei Zhang

2021 ◽  
Vol 13 (2) ◽  
pp. 211
Author(s):  
Maële Brisset ◽  
Simon Van Wynsberge ◽  
Serge Andréfouët ◽  
Claude Payri ◽  
Benoît Soulard ◽  
...  

Despite the necessary trade-offs between spatial and temporal resolution, remote sensing is an effective approach to monitor macroalgae blooms, understand their origins and anticipate their developments. Monitoring of small tropical lagoons is challenging because they require high resolutions. Since 2017, the Sentinel-2 satellites has provided new perspectives, and the feasibility of monitoring green algae blooms was investigated in this study. In the Poé-Gouaro-Déva lagoon, New Caledonia, recent Ulva blooms are the cause of significant nuisances when beaching. Spectral indices using the blue and green spectral bands were confronted with field observations of algal abundances using images concurrent with fieldwork. Depending on seabed compositions and types of correction applied to reflectance data, the spectral indices explained between 1 and 64.9% of variance. The models providing the best statistical fit were used to revisit the algal dynamics using Sentinel-2 data from January 2017 to December 2019, through two image segmentation approaches: unsupervised and supervised. The latter accurately reproduced the two algal blooms that occurred in the area in 2018. This paper demonstrates that Sentinel-2 data can be an effective source to hindcast and monitor the dynamics of green algae in shallow lagoons.


2021 ◽  
Vol 55 ◽  
pp. 102080
Author(s):  
Nancy A. Brown ◽  
Shirley Feldmann-Jensen ◽  
Jane E. Rovins ◽  
Caroline Orchiston ◽  
David Johnston

2021 ◽  
pp. 1-15
Author(s):  
Benjamin Richardson ◽  
Nina Hamaski

The rights-of-nature model is gaining traction as an innovative legal approach for nature conservation. Although adopted in several countries, it remains in its infancy, including in Australia. An important research question is whether rights of nature will offer superior environmental outcomes compared to traditional nature conservation techniques including creation of protected areas. This article investigates that question through a case study of the Tarkine wilderness, in the Australia state of Tasmania. It first identifies key lessons from existing international experience with affirmation of rights of nature, such as in New Zealand and Ecuador. The article then explores how rights of nature could apply in Australia’s Tarkine region and their value compared to existing or potential protected areas and other nature conservation measures under Australian or Tasmanian law. Affirming rights of nature represents a major conceptual shift in how people via the law relate to the natural world, but whether the model offers practical benefits for nature conservation depends on a variety of conditions, in addition to the need to address broader societal drivers of environmentaldegradation.


Sign in / Sign up

Export Citation Format

Share Document