Understanding Long-Term Changes of Coastal Saltmarshes from Satellite Remote Sensing

2020 ◽  
Author(s):  
Marieke Laengner ◽  
Daphne van der Wal
Keyword(s):  
Satellite Remote Sensing ◽  
Large Scale ◽  
Open Water ◽  
Google Earth ◽  
Environmental Drivers ◽  
Decision Tree Classification ◽  
Tidal Forces ◽  
Time Period ◽  
Long Time

<p>Saltmarshes are known to be very important coastal ecosystems. They provide crucial functions for flora and fauna, as well as valuable ecosystem services for humankind. Many methods that are used to investigate these ecosystems are limited in space and time. Long time series of global satellite data enable to observe changes in the extent of saltmarshes on a large scale and over a long time period. We developed an unsupervised decision tree classification method in Google Earth Engine that automatically classifies satellite images into saltmarsh vegetation, mudflats, and open water. We applied the method using Landsat 5 TM data between 1985 and 2011. With this, we are able to detect trends in the seaward extent of saltmarshes globally. We reveal transitions between saltmarsh, mudflat and open water. Furthermore, we put saltmarsh habitat changes in a spatial context and couple trends in saltmarsh dynamics to environmental drivers, such as sea level rise, tidal forces, waves, and sediment availability.</p>

scholarly journals Trends in the Seaward Extent of Saltmarshes across Europe from Long-Term Satellite Data

2019 ◽  
Vol 11 (14) ◽  
pp. 1653 ◽  
Author(s):  
Marieke Liesa Laengner ◽  
Koen Siteur ◽  
Daphne van der Wal
Keyword(s):  
Satellite Data ◽  
Large Scale ◽  
Open Water ◽  
Classification Performance ◽  
Environmental Drivers ◽  
Decision Tree Classification ◽  
Time Period ◽  
Long Time ◽  
Water Level Variations

Saltmarshes provide crucial functions for flora, fauna, and humankind. Thus far, studies of their dynamics and response to environmental drivers are limited in space and time. Satellite data allow for looking at saltmarshes on a large scale and over a long time period. We developed an unsupervised decision tree classification method to classify satellite images into saltmarsh vegetation, mudflat and open water, integrating additional land cover information. By using consecutive stacks of three years, we considered trends while taking into account water level variations. We used Landsat 5 TM data but found that other satellite data can be used as well. Classification performance for different periods of the Western Scheldt was almost perfect for this site, with overall accuracies above 90% and Kappa coefficients of over 0.85. Sensitivity analysis characterizes the method as being robust. Generated time series for 125 sites across Europe show saltmarsh area changes between 1986 and 2010. The method also worked using a global approach for these sites. We reveal transitions between saltmarsh, mudflat and open water, both at the saltmarsh lower edge and interior, but our method cannot detect changes at the saltmarsh-upland boundary. Resulting trends in saltmarsh dynamics can be coupled to environmental drivers, such as sea level, tidal currents, waves, and sediment availability.

scholarly journals Local Differential Privacy for Evolving Data

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Matthew Joseph ◽  
Aaron Roth ◽  
Jonathan Ullman ◽  
Bo Waggoner
Keyword(s):  
Large Scale ◽  
Differential Privacy ◽  
Statistical Information ◽  
Underlying Distribution ◽  
Specific Distribution ◽  
Time Period ◽  
Long Time ◽  
Heavy Hitter ◽  
Single Use ◽  
A New Technique

There are now several large scale deployments of differential privacy used to collect statistical information about users. However, these deployments periodically recollect the data and recompute the statistics using algorithms designed for a single use. As a result, these systems do not provide meaningful privacy guarantees over long time scales. Moreover, existing techniques to mitigate this effect do not apply in the “local model” of differential privacy that these systems use. In this paper, we introduce a new technique for local differential privacy that makes it possible to maintain up-to-date statistics over time, with privacy guarantees that degrade only in the number of changes in the underlying distribution rather than the number of collection periods. We use our technique for tracking a changing statistic in the setting where users are partitioned into an unknown collection of groups, and at every time period each user draws a single bit from a common (but changing) group-specific distribution. We also provide an application to frequency and heavy-hitter estimation.

Natural Analogues: Their Application to the Prediction of the Long-Term Behavior of Nuclear Waste Forms

1986 ◽  
Vol 84 ◽  
Author(s):  
Rodney C. Ewing ◽  
Michael J. Jercinovic
Keyword(s):  
Nuclear Waste ◽  
Borosilicate Glass ◽  
Large Scale ◽  
Laboratory Data ◽  
Waste Form ◽  
Long Time ◽  
Natural Analogues ◽  
Long Term Behavior ◽  
Nuclear Waste Forms

AbstractOne of the unique and scientifically most difficult aspects of nuclear waste isolation is the extrapolation ofshot-term laboratory data (hours to years) to the long time periods (103-105 years) required by regulatory agencies for performance assessment. The direct verification of these extrapolations is not possible, but methods must be developed to demonstrate compliance with government regulations and to satisfy the lay public that there is a demonstrable and reasonable basis for accepting the long-term extrapolations. Natural analogues of both the repository environment (e.g. radionuclide migration at Oklo) and nuclear waste form behavior (e.g. alteration of basaltic glasses and radiation damage in minerals) have been used to demonstrate the long-term behavior of large scale geologic systems and, on a smaller scale, waste form durability. This paper reviews the use of natural analogues to predict the long-term behavior of nuclear waste form glasses. Particular emphasis is placed on the inherent limitations of any conclusions that are based on “proof” by analogy. An example -- corrosion of borosilicate glass -- is discussed in detail with specific attention to the proper and successful use of natural analogues (basaltic glass) in understanding the long-term corrosion behavior of borosilicate glass.

Preliminary Study on Long-Term Flooding After the Tsunami

2017 ◽  
Vol 12 (4) ◽  
pp. 741-747
Author(s):  
Toshitaka Baba ◽  
Junichi Taniguchi ◽  
Noriko Kusunoki ◽  
Manabu Miyoshi ◽  
Hiroshi Aki ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Large Scale ◽  
Water Exchange ◽  
Ground Surface ◽  
Flow Modeling ◽  
Tsunami Waveforms ◽  
Long Time ◽  
Preliminary Study ◽  
Nankai Earthquake

After the Nankai earthquake in 1946, the resultant flooding lasted for a long time, because seawater remained on land after the tsunami in Kochi city. Large-scale flooding occurred in Ishinomaki city immediately after the Great East Japan Earthquake in 2011. Long-term flooding may hamper disaster responses such as rescue and recovery activities. This paper studied the risks of long-term flooding after the Nankai earthquake in Tokushima city based on a paleographical survey and numerical analysis. The paleographical survey identified statements such as “seawater sometimes flowed onto the land at the full tide,” suggesting occurrences of long-term flooding after previous Nankai earthquakes. The numerical analysis separately calculated values inside and outside the levee. The tsunami waveforms outside the analysis area obtained by tsunami numerical simulation was used as the boundary condition of the inland flow modeling, that is water was introduced inside the levee when the tsunami water level exceeded the upper end of the levee. The two layers of ground surface and the drain were defined to calculate the flow, including water exchange between the two layers, and the water was drained forcefully outside the levee using a drainage pump. The possibility of long-term flooding in the analysis area is suggested when a large-scale earthquake occurs in the Nankai trough.

scholarly journals Influence of treatment in multiple sclerosis dysability: an open, retrospective, non-randomized long-term analysis

2010 ◽  
Vol 68 (4) ◽  
pp. 511-521 ◽  
Author(s):  
Lineu Cesar Werneck ◽  
Paulo José Lorenzoni ◽  
Vitor A Radünz ◽  
Marco A.T Utiumi ◽  
Cláudia Suemi Kamoi Kay ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Disease Progression ◽  
Age Of Onset ◽  
Statistical Significance ◽  
Time Period ◽  
Disability Status ◽  
Therapeutic Procedures ◽  
Long Time ◽  
Final Score

The efficacies of immunosuppressive (IMS) and immunomodulatory (IMM) drugs for multiple sclerosis (MS) have been reported in several studies. These agents can reduce relapse rates and lesions observed by magnetic resonance imaging studies. However, the effect of these medications in disability progression over 4 years is rarely examined. OBJECTIVE: To study the disabilities associated with MS patients after a long time period and to analyze the therapeutic influence of different types of treatments in patient disease progression. METHOD: This is an open, uncontrolled, non-randomized, retrospective study of the disease progression using the Expanded Disability Status Scale (EDSS) and the Multiple Sclerosis Severity Score (MSSS) in 155 cases of MS, which were 76% female with a mean age of onset of 30.21±9.70. The follow-up period was 115.39±88.08 months (median 92, 3 to 447 months). These cases were submitted to the following 277 different therapeutic procedures: 62 without IMS or IMM therapy (SYT) (just corticosteroids), 53 with azathioprine (AZA), 53 interferon-β (IFNβ)-1b 250 µg (BET), 55 IFNβ-1a 22 µg (R22), 19 IFNβ-1a 30 µg (AVO), 15 IFNβ-1a 44 µg (R44), 15 glatiramer acetate (COP) 20 mg, and 5 cases with mitoxantrone (MIT). RESULTS: The median EDSS group was 2.00 (0 to 5.5, mean 1.89±1.52) at the onset of each treatment and 2.50 (0 to 9, mean 3.06±2.18) at the end. The median initial MSSS was 3.34 (0.25 to 9.50, mean 3.94±2.91) and the final medial was 3.90 (0.05 to 9.88, mean 4.02±2.78). The EDSS between initial and final score for the whole group had statistically significant progression, as well as for the sub-groups SYT, AZA, BET and R22. No statistically significance difference was found in the MSSS between initial and final scores in the whole group or treatment sub-groups. The variation between the initial and final EDSS and MSSS among the types of treatments found no statistical significance for any group. CONCLUSION: In this study series, no statistical difference was found in the long-term progression of disability among the IMS and IMM treated cases, nor in the cases treated only with corticosteroids.

scholarly journals KINEMATIC ANALYSIS EVOLUTION OF EXTENDED LANDSLIDES: TWO CASE STUDIES FROM WESTERN GREECE

2017 ◽  
Vol 50 (2) ◽  
pp. 730
Author(s):  
K. Kavoura ◽  
S. Anagnostopoulou ◽  
K. Servou ◽  
N. Depoundis ◽  
K. Nikolakopoulos ◽  
...  
Keyword(s):  
Statistical Model ◽  
Temporal Evolution ◽  
Data Normalization ◽  
Time Period ◽  
Long Time ◽  
Triggering Factor ◽  
The Common ◽  
Western Greece ◽  
Heavy Rainfalls

Two of the most well known historical landslide occurrences are analyzed and their temporal evolution is presented. The sites of Panagopoula and Karya are often referred as the most representative cases of long term ground displacements based on inclinometer monitoring data. Regarding these cases, the heavy rainfalls constitute the main controlling (triggering) factor, while flysch is the critical landslide-prone formation which significantly contributes to landsliding. The inclinometer data through a long time period were analyzed and typical movement diagrams were compiled. A simple statistical model including data normalization through several active stages (phases) of movement is used to identify the common kinematic features as well as to estimate the velocity trend type of movement.

scholarly journals Yet another lockdown? A large-scale study on people's unwillingness to be confined during the first 5 months of the COVID-19 pandemic in Spain

2021 ◽  
Author(s):  
Marina Martinez-Garcia ◽  
Alejandro Rabasa ◽  
Xavier Barber ◽  
Kristina Polotskaya ◽  
Kristof Roomp ◽  
...  
Keyword(s):  
Large Scale ◽  
Psychological Impact ◽  
Important Variable ◽  
Decision Makers ◽  
Policy Makers ◽  
Time Period ◽  
Economic Support ◽  
Gender And Age ◽  
The Impact

Population confinements have been one of the most widely adopted non-pharmaceutical interventions (NPIs) implemented by governments across the globe to help contain the spread of the SARS-CoV-2 virus. While confinement measures have been proven to be effective to reduce the number of infections, they entail significant economic and social costs. Thus, different policy makers and social groups have exhibited varying levels of acceptance of this type of measures. In this context, understanding the factors that determine the willingness of individuals to be confined during a pandemic is of paramount importance, particularly, to policy and decision-makers. In this paper, we study the factors that influence the unwillingness to be confined during the COVID-19 pandemic by means of a large-scale, online population survey deployed in Spain. We apply both quantitative (logistic regression) and qualitative (automatic pattern discovery) methods and consider socio-demographic, economic and psychological factors, together with the 14-day cumulative incidence per 100,000 inhabitants. Our analysis of 109,515 answers to the survey covers data spanning over a 5-month time period to shed light on the impact of the passage of time. We find evidence of pandemic fatigue as the percentage of those who report an unwillingness to be in confinement increases over time; we identify significant gender differences, with women being generally less likely than men to be able to sustain long-term confinement of at least 6 months; we uncover that the psychological impact was the most important factor to determine the willingness to be in confinement at the beginning of the pandemic, to be replaced by the economic impact as the most important variable towards the end of our period of study. Our results highlight the need to design gender and age specific public policies, to implement psychological and economic support programs and to address the evident pandemic fatigue as the success of potential future confinements will depend on the population's willingness to comply with them.

scholarly journals The evolution of Fedchenko glacier in the Pamir, Tajikistan, during the past eight decades

2014 ◽  
Vol 60 (220) ◽  
pp. 233-244 ◽  
Author(s):  
Astrid Lambrecht ◽  
Christoph Mayer ◽  
Vladimir Aizen ◽  
Dana Floricioiu ◽  
Arzhan Surazakov
Keyword(s):  
Drainage System ◽  
Volume Loss ◽  
Ablation Zone ◽  
Main Trunk ◽  
Time Period ◽  
Glacier Changes ◽  
Long Time ◽  
Small Change ◽  
Thickness Measurements

AbstractFedchenko glacier is by far the largest glacier in the Pamir, Tajikistan. Owing to early accurate mapping of the glacier it is possible to evaluate glacier changes over eight decades, which is an exceptionally long time period for this remote mountain region. During this time a total volume loss of 5 km3 was observed on the main trunk of the glacier, while the total area changed by only 1.4%. It is observed that the volume loss migrates from the lower parts of the glacier towards the upper ablation zone. The comparatively small change in area is a result of the supraglacial debris cover on the glacier tongue, which decouples the area loss from the volume loss to a considerable degree. The observed velocities of the glacier do not reflect the volume changes up to now because the interannual variability is larger than possible long-term changes so far. The intra-annual velocity distribution in the central ablation zone probably reflects the evolution of the basal drainage system. Based on ice thickness measurements and simple ice-dynamic assumptions, the total volume of Fedchenko glacier is 123.4 ± 8 km3.

Ecological research and large scale land-atmosphere feedbacks: lesson from the Bouchet's complementary relationship

2011 ◽  
Vol 8 (3) ◽  
pp. 6077-6094
Author(s):  
E. Lugato ◽  
G. Alberti ◽  
B. Gioli ◽  
J. O. Kaplan ◽  
A. Peressotti ◽  
...  
Keyword(s):  
Large Scale ◽  
Water Cycle ◽  
Potential Evapotranspiration ◽  
Short Term ◽  
Global Water Cycle ◽  
Long Time ◽  
Large Scale Land ◽  
Global Vegetation ◽  
Term Analysis

Abstract. Acceleration of the global water cycle over recent decades, which is hypothesized by several studies, remains uncertain because of the high inter-annual variability of its components. Observations of pan evaporation (Epan), a proxy of potential evapotranspiration (ETp), may help to identify trends in the water cycle over long time periods. The complementary relation (CR; Bouchet, 1963) states ETp and actual evapotranspiration (ETa) depend on each other in a complementary manner, through land-atmosphere feedbacks in water limited environments. Using a long time series of Epan observations in Australia, we estimated monthly ETa values using the CR and compared our estimates with ETa measured at eddy covariance stations in Fluxnet. Our results confirm that CR can be reliably applied to estimate ETa and produces better results than a global vegetation model run without specific calibration. In addition, our analysis indicated that, on average, ETa did not show any significant trend between 1975 and 2009 in Australia, but short-term analysis including anomaly periods may give the idea of a rapid climate change that is not perceived in a long-term perspective.

Use of tilt sensing equipment for monitoring long-term bridge movement

1991 ◽  
Vol 18 (6) ◽  
pp. 1033-1046 ◽  
Author(s):  
Terry J. Wipf
Keyword(s):  
Key Words ◽  
Reference Point ◽  
Structural Engineering ◽  
Field Tests ◽  
Measurement Instruments ◽  
Time Period ◽  
Long Time ◽  
Time Periods ◽  
Tilt Sensors

Accurate monitoring of long-term movements in bridges can be difficult primarily because of the relatively long time period over which the movements occur and inadequate instrumentation and technique. A stable reference point for measurements is difficult to obtain over these long time periods. Two bridges were monitored for long-term structural movement; the results are presented here. Instrumentation including temperature transducers and tilt sensors placed on and near piers determined the pier movement. The results of the study indicate that a superstructure expansion pier on one of the bridges monitored actually behaved as a fixed pier. The equipment used in the study, including data acquisition components and tilt sensors, proved reliable and accurate. Key words: bridges, girder, field tests, foundations, measurement instruments, piers, structural engineering.

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